PRAD Workshop 2026

10 Jun 2026, 19:00 → 12 Jun 2026, 17:30 Europe/Zurich

Valencia

Beatrice Fraboni (University of Bologna), Michele Sessolo (University of Valencia), Paul Sellin

PRAD 2026 is the next workshop in the occasional series of European meetings on perovskite radiation detectors, and will be held in Valencia. This follows the previous meeting in Bertinoro in 2023.

Please note that this is a private meeting, and that registration is only possible for invited teams. For futher information please contact the workshop organisers.

Attendees are encouraged to arrive on the evening of Wednesday 10 June. The workshop sessions will start at 9:00 on Thursday 11 June, and will finish by 14:00 on Friday 12 June.  

Thursday 11 June

08:30 Registration

Session 1: ABX3 Single Crystals (I)

1 Welcome

Opening Remarks

2 Challenges and Perspectives in Single Crystal ABX3 detectors

Speaker: Prof. Paul Sellin (University of Surrey)

3 Solution-processed growth of high-quality all-inorganic CsPbBr₃ perovskite single crystals via inverse temperature crystallization for optoelectronic detector applications

Perovskite single-crystal semiconductors represent the pinnacle of material quality for optoelectronic applications, offering dramatically reduced trap densities, suppressed grain boundary scattering, and longer charge carrier diffusion lengths compared to their polycrystalline counterparts. all-inorganic cesium lead bromide (CsPbBr₃) has attracted extraordinary research attention owing to its exceptional combination of a direct bandgap (~2.1-2.2 eV), high atomic number constituents, superior ambient stability, and tunable optical properties characteristics that collectively make it a compelling candidate for high-performance photodetectors and ionizing radiation sensors. successful synthesis of high-quality CsPbBr₃ perovskite single crystals (PSCs) at a remarkably low processing temperature of 65°C via the inverse temperature crystallization (ITC) method. Structural characterization by powder X-ray diffraction confirmed the high crystallinity of the grown crystals. Optical characterization revealed a sharp photoluminescence emission at 565 nm, and a bandgap of ~2.18 eV was extracted from the Tauc relationship applied to UV-Vis absorption spectra

Speaker: RAMASHANKER GUPTA (Charles University)

4 Synchrotron X-ray Microbeam Characterisation of Melt- and Solution-Grown Lead Halide Perovskite Single Crystal Devices

To enable production of viable pixellated X-ray detectors, single-crystal perovskite devices must demonstrate operational stability and spatially uniform performance. In addition, while the low cost of solution-grown crystals is attractive, cheaper semiconductor crystals deliver only modest savings in overall detector costs. This means that comparative measurements must show performance for solution-grown crystals which is close to or surpasses that of low-defect melt-grown devices. Here, we present results of synchrotron experiments in which the X-ray detection performance of melt-grown CsPbBr$_3$ devices from Actinia and solution-grown FAPbBr$_3$ devices from the University of Surrey and the University of Cambridge were each measured at fluxes up to 10$^9$ ph/s/mm2.

Speaker: Dr Isabel Braddock (Science and Technology Facilities Council)

5 Identification and control of interfacial limits enabling high-performance photon-counting perovskite radiation detectors

Lead halide perovskite single crystals are promising for high-resolution photon-counting radiation detection due to their high atomic number and favourable charge-transport properties$^{[1]}$. However, most devices operate in hole-transport configurations, while currently existing application specific integrated circuits (ASICs) readout electronics are optimised for electron collection$^{[2]}$. Bridging this mismatch requires a clear understanding of carrier-polarity-dependent transport and the underlying device physics governing perovskite detectors.
We fabricate planar Schottky detectors based on formamidinium lead bromide (FAPbBr$_3$) perovskite single crystals with an Au/FAPbBr$_3$/Bi architecture. High-quality solution-grown FAPbBr$_3$ single crystals with X-ray rocking-curve linewidths as narrow as 0.0047° (16.9 arcsec) are used for detector fabrication. We investigate charge transport and stability of FAPbBr$_3$ planar detectors using α-particle ($^{241}$Am, 5.48 MeV) spectroscopy as a carrier-selective probe. By controlling the irradiation side and bias polarity, we isolate hole- and electron-transport signal formation and directly compare their spectroscopic response. Fresh devices exhibit superior hole transport, with energy resolution reaching 3.9% under α-particle excitation, whereas electron transport yields a broader energy resolution of 8.9%.
Upon continuous biasing (36 h at 5,000 V cm$^{-1}$) and shelf-life ageing (1 month), we observe pronounced polarity-dependent degradation. Hole signals collapse, accompanied by a substantial reduction in μτ (from 1.2 × 10$^{−3}$ cm$^{2}$ V$^{−1}$ to 5.2 × 10$^{−5}$ cm$^{2}$ V$^{−1}$) and the emergence of delayed pulse components, whereas electron transport shows only minor degradation, with μτ decreasing from 4.2 × 10$^{−4}$ to 2.6 × 10$^{−4}$ cm$^{2}$ V$^{−1}$.
Polarity-resolved α-particle measurements further reveal that degradation is strongly location-dependent. When carriers are generated near the Bi electrode, both hole and electron signals deteriorate after ageing, independent of bias polarity, indicating permanent degradation localised beneath the Bi contact. In contrast, analysis of the Au side via spatially resolved photoluminescence and time-resolved measurements (after electrode removal) shows a defect-rich interfacial region with enhanced non-radiative recombination.
These results demonstrate that charge transport in FAPbBr$_3$ detectors is primarily governed by metal/perovskite interfacial processes rather than intrinsic bulk properties. The observed asymmetry between electron and hole transport originates from localised interfacial defect formation, which selectively limits carrier extraction depending on the generation site.
Introduction of ultrathin interfacial layers (e.g., Ti or Cr) mitigates these effects, enabling stable hole- and electron-transport operation. Detectors remain stable after ~100 h of continuous biasing at 5,000 V cm$^{-1}$ and ~3 months of shelf-life storage.
The combination of high-quality crystals and interfacial protection layers enables the detectors to achieve 1.3% energy resolution for 662 keV ($^{137}$Cs γ-ray source) and 6.1% for 5.48 MeV α-particles in an electron-transport configuration. This work establishes interfacial degradation as the dominant performance-limiting factor in perovskite radiation detectors and identifies interfacial engineering as the key pathway toward stable, high-resolution hole- and electron-transport spectroscopy, providing a pathway toward compatibility with photon-counting ASIC architectures.

References
1. He, Y., Hadar, I. & Kanatzidis, M. G. Nat. Photon. 16, 1–13 (2022).
2. Mirzaei, A., Huh, J.-S., Kim, S. S. & Kim, H. W. Electron. Mater. Lett. 14, 261–287 (2018).

Speaker: GANBAATAR Tumen-Ulzii (University of Cambridge)

10:30 Coffee Break

Session 2 ABX3 Single Crystals (II)

6 Group Overview - Charles University Prague

Speaker: Roman Grill (Charles University, Faculty of Mathematics and Physics)

7 FAPbBr₃ Single Crystal Perovskite Radiation Detectors with Embedded Electrode Architecture

Formamidinium lead bromide (FAPbBr₃) single crystal perovskites have recently emerged as a key candidate for commercially viable radiation detectors. They have attracted attention due to their high performance and low temperature solution processability, enabling low cost fabrication. An underexplored consequence of this fabrication route is the ability to crystallise around pre-placed structures. This enables the possibility of detectors with an embedded electrode architecture.
Silicon radiation detectors with embedded electrodes manufactured by etching are an established technology and have been deployed for high energy radiation physics applications in CERN. However, this architecture is not achievable for high-performance compound semiconductors such as CdTe and CZT as etching would destroy their fragile crystal structure and in-situ electrode encapsulation is not compatible with their CVD growth process.
A criticism of perovskite detectors is their modest carrier mobility compared to CZT or silicon, which demands prohibitively high electric fields to achieve the collection times required for ASIC integration and meaningful data rates for medical imaging. Detectors with embedded electrodes to collect charge carriers laterally, thus reducing the charge carrier transit time and trap probability compared to the planar configuration, holds promise to directly address this limitation.
This research presents the growth of FAPbBr₃ single crystals around a 2x2 array of gold wire electrodes, showing the first demonstration of this device architecture in a FAPbBr₃ single crystal radiation detector. Initial characterisation demonstrated a linear I-V response and sensitivity to X-rays. Future work will scale to a larger array with an increased area targeting gamma-ray spectroscopic performance with fast signal pulse rise times.

Speaker: Seán Cardiff

8 Transient Spectroscopy Investigation of Deep Trap States and Stability in Perovskite Radiation Detectors

The deployment of metal halide perovskites (MHPs) in radiation detection is still limited by long-term instability, ion migration, and the presence of deep trap states that critically affect charge transport, and signal stability under ionizing radiation. Understanding defect dynamics is therefore essential to enable reliable detector operation.
Here, we investigate defect states and radiation hardness across different perovskite systems, combining studies on 3D and 2D lead halide crystals (MAPbBr₃ and PEA₂PbBr₄) with a mixed-cation, mixed-halide composition, relevant for scalable device architectures. Deep-level defects are probed using Photo-Induced Current Transient Spectroscopy (PICTS), a technique suited for high-resistivity materials and capable of resolving trap activation energies under operating-like conditions.
For the 2D layered perovskite (PEA)₂PbBr₄, PICTS measurements reveal clear fingerprint of deep trap states, with activation energies extracted through Arrhenius analysis. Thanks to the reduced ionic mobility of the 2D structure, these trap levels can be reliably identified and tracked under external stress. Importantly, the defect signature remains stable under thermal cycling, electrical bias, and prolonged X-ray irradiation, demonstrating strong intrinsic radiation tolerance. This behavior contrasts with 3D perovskites, where ion migration dominates the transient response and limits the extraction of defect parameters.
The technique has been further employed to investigate and to assess defect formation in thin film complex compositions. A single dominant trap level is identified, consistent with interstitial halide defects. Time-dependent and bias-dependent measurements indicate a relatively stable defect population, despite the increased compositional disorder. To enhance environmental robustness and ensure stable detector operation, a Cytop capping layer is introduced, effectively reducing interaction with moisture and oxygen and changing the defective levels.
A comparative analysis between single crystals and polycrystalline films highlights the impact of morphology on charge transport and defect sensitivity. Furthermore, X-ray exposure studies suggest a correlation between defect evolution and improved operational stability, potentially linked to radiation-induced defect passivation. Overall, these results provide key insights into defect-controlled charge transport in MHP-based detectors and demonstrate that 2D perovskites and optimized mixed-cation systems offer a viable pathway toward radiation-hard, stable, and scalable direct X-ray detection technologies.

Speaker: Andrea Ciavatti (DIFA - Università di Bologna)

9 CsPbBr3 microcrystals washing strategy enables low dark current and improved limit of detection for X-ray detection

All-inorganic CsPbBr₃ perovskite has emerged as a potential material for optoelectronic applications such as solar cells, LEDs, photodetectors, and X-ray detectors, owing to its superior charge-transport properties, long carrier diffusion length, and broad light absorption.¹ In contrast to its organic counterparts such as MAPbBr₃ (MA = methylammonium), all-inorganic CsPbBr₃ exhibits superior photostability, thermal stability, and moisture stability, making it a suitable candidate for high-energy radiation detection.²

Dimethyl sulfoxide (DMSO) is a widely used solvent for the synthesis of halide perovskites (HPs); nevertheless, its intrinsically high viscosity and boiling point can lead to degradation and reduced optoelectronic performance in the resulting perovskite films due to DMSO trapping during film formation, which generates voids.³ One of the major issues with CsPbBr₃ is the large dark current generated by the intrinsic ionic-migration nature of the material.² Such large dark currents can compromise device stability and degrade X-ray image quality.

In this presentation, I will discuss the synthesis of CsPbBr₃ microcrystals (~20/50 μm) for X-ray detection. I will elaborate on the impact of washing these DMSO-synthesized microcrystals with different solvents (such as ethanol (EtOH) and ethyl acetate (EA)) and examine how these solvents affect the structural, optical, and X-ray detection properties of CsPbBr₃ microcrystals. To evaluate their practical applicability, proof-of-concept X-ray detectors based on wafers composed of these microcrystals have been developed.

Compared with their non-washed counterparts, CsPbBr₃ microcrystals washed with a combination of EA and EtOH exhibit reduced dark current and suppressed dark-current drift. This reduction in dark current leads to an improved on/off ratio and an X-ray limit of detection (LoD) enhanced by more than one order of magnitude.

(1) Clinckemalie, L. et al. Phase-Engineering Compact and Flexible CsPbBr3 Microcrystal Films for Robust X-Ray Detection. J. Mater. Chem. C 2024, 12 (2), 655–663.

(2) Clinckemalie, L. et al. Challenges and Opportunities for CsPbBr3 Perovskites in Low- and High-Energy Radiation Detection. ACS Energy Lett. 2021, 6 (4), 1290–1314.

(3) Chen, S. et al. Stabilizing Perovskite-Substrate Interfaces for High-Performance Perovskite Modules. Science 2021, 373 (6557), 902–907.

Speaker: Nil Monros (KU Leuven)

12:30 Guided Walk of Gardens

13:00 Lunch

Session 3: 2D Perovskites

10 Group overview - Bologna University

Speaker: Beatrice Fraboni (University of Bologna)

11 Weak exciton–phonon coupling in two-dimensional perovskite thin films for high-performance UV photodetection

Two-dimensional layered hybrid perovskites are promising candidates for UV-visible photodetection due to their tunable bandgap, high absorption coefficients, and excellent environmental stability. However, the influence of processing methods on fundamental excitonic properties and device performance remains poorly understood. In this work, we demonstrate that the deposition technique fundamentally determines the degree of crystalline order, the strength of exciton–phonon coupling, and ultimately the photodetection regime in PEA2PbBr4-based flexible UV photodetectors.
We compare two solution-processing methods (spin coating and bar coating) applied to the fabrication of PEA2PbBr4 thin films on flexible polyimide substrates. Structural characterization by X-ray diffraction reveals that bar-coated films exhibit sharper diffraction peaks, reduced microstrain, and larger crystalline domains compared to spin-coated films. Optical microscopy confirms improved morphological homogeneity with fewer grain boundaries and better domain connectivity in bar-coated samples.
Temperature-dependent photoluminescence spectroscopy in the 80–300 K range provides direct evidence of the impact of processing on excitonic properties. At low temperatures, both samples develop a distinct double-peak structure corresponding to localized (low-energy, LE) and delocalized (high-energy, HE) excitonic states. However, the analysis of temperature-dependent linewidth broadening reveals striking differences. In bar-coated films, the effective exciton–phonon coupling constant for the HE excitonic transition is significantly reduced compared to spin-coated films. Furthermore, inhomogeneous broadening due to static disorder in the LE peak shows a dramatic reduction from 90 meV to 51 meV, indicating substantially improved crystalline quality.
These spectroscopic differences translate directly into device performance. Under 385 nm UV illumination, bar-coated photodetectors achieve responsivities of 40 mA/W and specific detectivities exceeding 10^(13) Jones at low optical flux, while maintaining ultra-low dark currents below 100 fA. These values place our flexible, solution-processed thin-film devices among the top-performing perovskite UV photodetectors reported to date. In contrast, spin-coated devices operate in a trap-limited regime with responsivities two orders of magnitude lower, directly reflecting the stronger exciton–phonon coupling and higher structural disorder revealed by photoluminescence measurements.
Our results establish that controlling film formation through deposition method selection offers a direct pathway to tune fundamental excitonic properties and drive flexible 2D perovskite films from polycrystalline trap-dominated transport toward quasi-single-crystal-like behavior. This work advances both the fundamental understanding of exciton dynamics in low-dimensional perovskites and the practical development of scalable, flexible radiation detectors for UV sensing applications.

Speaker: Elisabetta Colantoni

12 Hybrid 2D Perovskite Thin Films for Fast and Thermal Neutron Direct Detection

Metal halide perovskite detectors have been extensively investigated in recent years, particularly for photon detection (e.g. vis-UV, X-ray, γ-ray), owing to their excellent optoelectronic properties, high absorption coefficients, and defect tolerance. Only more recently, their potential has been explored for the detection of other types of ionizing radiation, including charged particles (protons, alpha particles, and electrons) and neutrons. In this context, a key advantage of perovskite-based devices deposited from solution lies in their intrinsic versatility, which allows the detection mechanism to be tailored either through the correct selection of the most suitable active material or by the specific functionalization of the device architecture and layers, thereby enabling sensitivity to different types of radiation characterized by distinct interaction mechanisms with matter.
The detection of fast neutrons is crucial for several applications, including medical imaging, radiation therapy, and non-destructive inspection. However, neutron detection remains challenging due to their charge neutrality and the resulting low interaction cross-section with matter. In solid-state detectors, fast neutron detection typically relies on elastic scattering processes, where kinetic energy is transferred to the detector material. Hybrid organic–inorganic metal halide perovskites are particularly promising in this regard: the presence of low-Z organic components enhances the efficiency of energy transfer via elastic scattering, while the inorganic framework efficiently collects the energy deposited by recoil particles.
Here [1], we report on flexible, thin-film detectors based on the 2D perovskite PEA₂PbBr₄, deposited from solution onto gold interdigitated electrodes in a coplanar configuration on polyimide substrates. These devices demonstrate direct fast neutron detection, providing an electrical signal proportional to neutron flux. By optimizing the deposition process, we achieved stable and reproducible real-time monitoring under neutron irradiation (energy range 1–4 MeV, flux 0.4–3 × 10⁵ n s⁻¹). Furthermore, the reduced thickness of the perovskite layer (1–4 µm) limits γ-ray interactions, improving neutron/gamma discrimination compared to bulk single-crystal devices.
The detection of thermal neutrons is equally crucial for applications such as nuclear safety, reactor monitoring, and emerging radiotherapy techniques like Boron Neutron Capture Therapy (BNCT). In this case, the detection mechanism relies on neutron capture processes in high cross-section materials, and recent studies have begun to demonstrate the feasibility of perovskite-based direct detectors by translating established concepts from silicon-based technologies to this novel material platform. Here we will show preliminary results on thermal neutron detection by integrating 10B-based converting structures within the 2-termanal solid state detector already employed for fast neutrons. The high thermal neutron capture cross-section of 10B enables efficient conversion of thermal neutrons into charged particles, which can then be detected by the perovskite layer. This strategy highlights the versatility of perovskite-based platforms, where material and device functionalization can be combined to target different neutron energy ranges within a unified technological framework.
Overall, these results demonstrate that perovskite thin-film devices represent a promising and highly adaptable platform for neutron detection, with potential applications in compact, flexible, and wearable dosimetry systems capable of real-time radiation monitoring.

[1] Fratelli I., B. Fraboni et al., (2025). Adv. Funct. Mat., adfm.202502530.

Speaker: Ilaria Fratelli (University of Bologna)

13 Growth, Pellet Fabrication and Optical Characterisation 2D Perovskite Scintillators

Two-dimensional (2D) hybrid perovskite materials have emerged as promising candidates for next-generation scintillators due to their high light yields, fast radiative recombination and low-temperature solution-processability [1]. Unlike conventional scintillators, these materials offer exceptional structural and compositional tunability through variation of the organic spacer and inorganic framework, enabling precise control over their optical and scintillation properties.
The aim of this study is to develop a bright, efficient radiation detector using different fabrication processes such as doping and pellet pressing. In this work, we report the fabrication and characterisation of the 2D perovskites n-butylammonium lead bromide (BA2PbBr4), phenethylammonium lead bromide (PEA2PbBr4) tetramethyl-1,3-propanediamonium lead bromide (TMPDAPbBr4) and using several techniques. High-quality crystals are grown using a slow-cooling method, yielding large 2cmx2cm sized crystals up to 1.5mm thick. Dopants such as Manganese and Rubidium can be incorporated into the initial solution. Dopants allow desirable properties to be selected such as enhanced light yields, emission wavelengths and lifetimes.
For practical handling and scintillation measurements, the as-grown crystals can be ground into a fine powder and compressed into pellets using a hydraulic press. This process enables uniform sizes and thicknesses of material. PEA2PbBr4 single crystals and pellets show a higher light yield compared to commercial scintillator LYSO. BA2PbBr4 and PEA2PbBR4 also shows a strong response to gamma radiation with resolvable peaks. A further advantage of these three perovskites is their uniquely short lifetime under 10ns compared to LYSO at 40ns and other commercial scintillators in the millisecond range [2]. Traditional scintillator materials also often suffer from high fabrication costs and limited tunability. These 2D perovskites therefore serve as a promising candidate for the next generation of scintillators for radiation detection.

[1] A. Xie, F. Maddalena, M. E. Witkowski, et al., Library of two-dimensional hybrid lead halide perovskite scintillator crystals, Chemistry of Materials, vol. 32, no. 19 2020, pp. 8530–8539, 2020.
[2] G. F. Knoll and H. W. Kraner, Radiation Detection and Measurement. 1981, vol. 69, p. 495, ISBN: 0471073385. DOI: 10.1109/PROC.1981.12016.

Speaker: Amy Dickinson (University of Surrey)

15:30 Coffee Break

Session 4: Vapour Deposited Perovskites

14 Solvent-Free Preparation of Perovskite Films and Solids for Optoelectronics

Lead and tin halide perovskites are among the most promising materials for next-generation photovoltaic and photodetector technologies. Despite the potential for widespread adoption in the industrial sector, solvent-free deposition of perovskite films remains relatively underexplored. Here, we present some of the latest advancements in the stabilization of perovskite films prepared by vapor deposition, with particular emphasis on methods to manipulate their morphology and structure. The impact of composition and deposition conditions on semiconductor properties and performance of solar-cell is discussed. We then discuss the application of thin perovskite films in the detection of optical and X-ray photons. In addition, we present a dry synthetic method for preparing functional flexible pellets starting from raw chemical precursors. Finally, we demonstrate the use of these flexible pellets in ionizing radiation detectors.

Speaker: Michele Sessolo (University of Valencia)

15 Vapour-Deposited Perovskite Thin-Film Photodetectors on unconventional substrates

Metal halide perovskites are promising candidates for numerous applications in optoelectronic devices due to their remarkable properties, including high absorption coefficients, high carrier mobility, simple fabrication processes, and the ability to tailor their composition for specific applications. Furthermore, the presence of high-Z elements such as Pb, Sn, and Cs in their structure makes them attractive for applications requiring high radiation hardness. Vapour deposition techniques offer conformal, large-area coating with precise thickness control. Importantly, the absence of an annealing step enables the deposition of perovskites on sensitive substrates. In this work, we demonstrate thin-film perovskite photodetectors that perform equally well in superstrate, substrate, and bifacial configurations, achieving a specific detectivity of 5×10¹² Jones at −0.5 V under 750 nm illumination. We demonstrate high-performing devices fabricated on opaque and plastic substrates, providing a viable solution for the integration of these detectors with other technological platforms.

Speaker: Mr Serhii Derenko (University of Valencia)

16 Engineering Large-Grain Metal Halide Perovskite films via Chemical Vapor Deposition for High-Performance, Ultralow-Noise Perovskite Photodetectors

Metal halide perovskites have emerged as promising semiconductors for high-performance photodetectors and X-ray sensors due to their high-Z composition, excellent charge transport, and intrinsic defect tolerance. However, scalable fabrication of thick, pinhole-free films with controlled crystallinity and long-term stability remains challenging, limiting their device performance. Here, I demonstrate the chemical vapor deposition of large-grain, phase-pure CsPbBr₃ films with thicknesses of ~3 µm and grain sizes up to 35 µm, an order of magnitude larger than those obtained by conventional spin coating. By optimizing deposition parameters and substrate selection, we achieve smooth, uniform films with prolonged carrier decay times and enhanced charge transport, as evidenced by time-resolved photoluminescence and Drude-like behavior in terahertz photoconductivity measurements. Photodetectors based on these films exhibit ultralow dark currents (<1 pA cm⁻² at 0 V), high switching ratios (~10⁴), responsivities up to 0.176 A W⁻¹, and detectivities of 8.4 × 10¹² Jones, while maintaining exceptional operational and ambient stability over one year. X-ray sensitivity measurements further confirm the potential of these devices for low-dose detection applications. This work establishes CVD as a scalable, solvent-free route to high-quality halide perovskite films, providing a clear pathway to next-generation photodetectors and X-ray sensors with superior performance and long-term stability.

Speaker: Roel Vanden Brande (KU Leuven)

17 Vacuum-deposited 2D perovskite film as a radiation scintillator

While three-dimensional (3D) halide perovskites demonstrate potential for X-ray detection, their commercial feasibility is severely constrained by ion migration, which induces baseline drift and environmental instability. Two-dimensional (2D layered perovskite such as (BA)2PbBr4 offer an alternative by providing physical barriers to halide ion diffusion and exploiting low dielectric screening to obtain high exciton binding energies for efficient radiative recombination. In this study, the fabrication of 2D (BA)2PbBr4 film using a scalable, solvent-free single-source vacuum deposition (SSVD) technique produces an ultra-thick film (10.5 ± 4.0µm), which records a sensitivity of 2464 µC Gy⁻¹ cm⁻² and a limit of detection 66 nGy s⁻¹. To understand the parameters that influence film quality, the effects of substrate temperature, source-substrate distance and precursor mass on film morphology and stoichiometry are systematically investigated. The findings reveal that increasing substrate temperature above 40°C lowers the sticking coefficient drastically, leading to extensive void formation up to 90% at 60 °C and severe stoichiometric degradation. Although a shorter source- substrate distance introduces a structural trade-off through increased surface roughness, the high deposition flux ensures full film surface coverage and a near-ideal Br/Pb stoichiometric ratio. This work highlights that precise SSVD parameter optimisation is important for fabricating a high-stability and scalable X-ray perovskite scintillator.

Speaker: MUZZAMER BIN MOHAMMAD ZAHID (University of Surrey)

18 Close-Space Sublimation of CsPbBr3 for advanced medical X-ray imaging

APbBr3 (A = FA, Cs) perovskites have emerged as benchmark materials for X-ray and gamma-ray detection, combining excellent X-ray stopping power with high processability. While FAPbBr3 is typically processed in solution, the congruent melting nature of CsPbBr3 allows synthesis from melted precursors or via vacuum deposition techniques. However, scalable fabrication that meets device performance requirements remains challenging.

Close space sublimation (CSS) represents an attractive, industry-relevant deposition technique due to its high growth rates, solvent-free process, and compatibility with large-area manufacturing. Nevertheless, the single-source nature of CSS and the close proximity between the material source and substrate require careful control over deposition conditions.

This work demonstrates the growth of CsPbBr3 films using CSS, exploring the flexibility of process parameters to tune film properties. Key findings establish CSS as an effective technique for depositing high-quality polycrystalline CsPbBr3 films with thicknesses ranging from nanometers to hundreds of micrometers. Remarkable growth rates from 1 to 15 μm/min, along with the ability to tailor film morphology and deposited surface area using shadow-masking, highlight the advantages of CSS for perovskite absorber deposition. The fabrication of fully functional 4 × 4 cm² imagers on TFT pixelated backplanes is demonstrated, establishing CSS as a promising technique for dynamic X-ray imaging applications. First demonstrators of large-area 20 × 20 cm² X-ray imagers are presented, paving the way for advanced X-ray radiography. Finally, the potential of CSS for growing more complex perovskite compositions, including hybrid structures such as FAPbBr3, is discussed.

Speaker: Ferdinand Lédée (CEA)

Posters & Networking

19 Bulk and Surface Optimizations of FAPbBr3 Single Crystals for Radiation Detection

Over recent years, perovskite semiconductors have gained interest as radiation detection, one of which is formamidinium lead bromide single crystals (FAPbBr3 SCs). FAPbBr3 has been shown to be one of the more promising candidates to act as a radiation detector, however it faces many challenges during the growth and polishing processes that effect the bulk and surface properties. Recent studies have shown that issues FAPbBr3 SCs face such as lifetime, uniformity, dark currents and ion migration are caused by strain in the bulk and nonuniformity of the surface of the crystal, leading to the viability of FAPbBr3 to fail to contend with commercially used photodetectors, especially when detecting gamma radiation. Therefore, this work aims to focus on looking into the bulk and surface properties of the SCs by optimizing the growth process of FAPbBr3 SCs through the temperature ramps used during the inverse temperature crystallization (ITC) growth process. This could serve as a means of addressing the bulk issues, while surface issues are to be investigated by looking into the polishing processes. The optimizations were checked by use of digital microscopy to check the surface uniformity and the transparency, and cross polar microscopy was used to check the bulk strain distribution within the crystals. Then once the crystals showed promise, they were fitted with asymmetrical contacts (Bi/FAPbBr3/Au) in a device, and the dark currents were tested using polar biased voltage responses, continuous voltage responses and X-ray scans to see the effects of ion migration within the crystals. These optimizations and verification tests would lead to higher quality single crystals and thus better detector properties.

Speaker: Jenson Green (University of Surrey)

20 Flexible and High-Performance Perovskite-Polymer Composites for Dual X-Ray and Proton Direct Detection

The demand for low-cost, easy to produce, flexible, and lightweight ionizing radiation detectors has grown extensively recently. Metal halide perovskites can meet all the demands of innovative radiation detectors and have rapidly outperformed the sensitivity of standard detectors.[1]
Here, we present perovskite-based composites fabricated by simple, low-cost, air-processed, dry mechanochemical synthesis of CsPbBr3 in a poly(butyl methacrylate) (PBMA) matrix.[2,3] The technique allows reproducible and easily scalable fabrication of thick perovskite pellets, by pressing the precursors into free-standing thick disks of thickness up to several hundreds of micrometres. Subsequently, the disks can be laminated onto a substrate with patterned electrodes to make photoconductors suitable as detectors of ionizing radiation. By tuning the polymer content, it is possible to achieve an extremely stable direct X-ray detection with good sensitivity. The devices are stable in air, bias and they are radiation hard, making them suitable for ionizing radiation detection in real-life applications. The perovskite-polymer composites are further investigated in vertical electrodes geometry to improve the charge collection efficiency. The vertical device configuration allows obtain a sensitity which is more than douled compared to a co-planar electrode geometry with the same active layer thickness (100 µm) and at the same applied electric field. The sensitivity can be further improved increasing the active layer thickness up to 500 µm, which is achievable thanks to the versatility of the dry-pressing fabrication technique. When laminated onto PET plastic substrate, the devices show outstanding flexibility properties reaching a bending radius of 1 mm with unaltered radiation response for a 100 µm thick device. Furthermore, the devices were tested also under a 5 MeV proton beam, demonstrating to make suitable flexible proton detectors.
To conclude, the synthesis of polymer micro-encapsulated perovskite pellets through simple, scalable, dry processes is promising for the development of flexible, stable, and highly sensitive ionizing radiation detectors.

[1] Dudipla K.R. et al, Adv. Mater. 2023, 2304523
[2] B. Huisman et al, Adv. Funct. Mater. 2024, 2308844
[3] C. Bordoni et al, Adv. Opt. Mater. 2026 e00004.

Speaker: Camilla Bordoni

21 Investigation of Defect States in FAPbBr3 and CsPbBr3 Single Crystals using TSC Measurements

This work presents a comparative study of defect states in FAPbBr₃ and CsPbBr₃ single crystals using thermally stimulated current (TSC) measurements. Trap states were investigated over a temperature range of 100–300 K to identify dominant trapping centres. TSC spectra reveal multiple trap levels with varying activation energies in both materials. Data analysis was performed using the Simultaneous Multiple Peak Analysis (SIMPA) method to extract individual trap parameters. These parameters were then used to quantitatively determine the capture cross section (D), trap density (N), and trap activation energy (E). Both crystals exhibit a combination of shallow and deep traps with varying concentration levels, and we will compare the defect signature of both solution-grown and Bridgman perovskite crystals. These findings provide insight into charge trapping mechanisms relevant for radiation detection performance and highlight the importance of defect analysis in optimising perovskite-based detectors.

Speaker: Sithumini Perera (School of Mathematics and Physics, University of Surrey)

22 Impact of Device Architecture on Proton Detection Efficiency in 2D Perovskite Thick Film Detectors

Developing flexible and lightweight detectors for real-time ionizing radiation monitoring is becoming increasingly important for applications in medicine, space, nuclear safety, and accelerator-based research. Hybrid perovskites offer an attractive route toward this goal, combining high absorption with simple and scalable solution processing. Within this material class, two-dimensional perovskites are particularly appealing due to their structural tunability, and enhanced stability compared with three-dimensional counterparts.
In particular, previous studies have demonstrated the effective use of two-dimensional perovskites for direct proton detection in planar thin-film architectures, highlighting their suitability for operation in radiation-harsh environments. [1,2] However, the conventional planar geometry imposes intrinsic limitations on charge extraction. A stacked architecture can address this issue by applying the electric field through the film thickness, thereby promoting charge collection across the full active volume. Although vertical electrode configurations have been widely explored in single-crystal perovskite detectors and are routinely used in thin-film photovoltaics, their implementation in thicker solution-processed films remains challenging. In radiation detectors, increasing the active-layer thickness can be advantageous because it enhances the interaction volume. At the same time, thicker films require high uniformity to prevent pinholes, short circuits, and local electric-field distortions, which would otherwise compromise stable detector operation.

Here, we investigate flexible stacked thick-film detectors based on two-dimensional phenethylammonium lead bromide perovskite and compare their performance with that of planar devices under direct 5 MeV proton irradiation. Devices with active-layer thicknesses of 2 and 10 µm were fabricated on plastic substrates and tested at the Laboratory of Nuclear Techniques for Environment and Cultural Heritage (INFN, Florence, Italy), using fluence rates between 10⁸ and 10¹¹ H⁺ cm⁻² s⁻¹. This comparison reveals a clear advantage of the stacked configuration, which provides a stronger and more tunable response than the planar counterpart over applied electric fields ranging from 0.05 to 0.5 V µm⁻¹. The vertical devices also display high radiation tolerance and stable operation over time, with their response retained after five months of storage in air. Overall, this work establishes vertical two-dimensional perovskite thick films as a robust platform for charged-particle detection. [3]

[1] Basiricò, Laura, et al. "Mixed 3D–2D perovskite flexible films for the direct detection of 5 MeV protons." Advanced Science 10.1 (2023): 2204815.

[2] Fratelli, Ilaria, et al. "Real‐Time Radiation Beam Monitoring by Flexible Perovskite Thin Film Arrays." Advanced Science 11.40 (2024): 2401124.

[3] Napolitano, Giulia, et al. "Impact of Device Architecture on Proton Detection Efficiency in 2D Perovskite Thick Film Detectors." Small (2026): e12236.

Speaker: Giulia Napolitano (Department of Physics and Astronomy, University of Bologna, Italy)

23 One-pot synthesis of quasi 2D/3D perovskite based heterostructure for enhanced X-ray detection: Breaking the sensitivity dark current trade-off

Exposure to high doses of X-rays poses significant health risks due to their high photon energy and deep penetration, necessitating the development of highly sensitive detectors capable of operating at low photon doses for safer medical imaging. Perovskite materials have emerged as promising candidates for X-ray detection, with research evolving from organic systems (e.g., CH₃NH₃PbBr₃) to inorganic counterparts (CsPbBr₃) owing to their superior photo-, thermal-, and moisture stability.1 However, challenges such as material instability and high dark current continue to limit their practical application.2

Low-dimensional perovskites, particularly quasi-2D structures composed of inorganic slabs separated by organic cations, offer enhanced structural stability. Nevertheless, they often suffer from limited charge transport and reduced sensitivity. To address these limitations, semiconductor heterostructure engineering has emerged as an effective strategy, combining the advantages of different components to improve charge separation and transport while suppressing undesirable effects such as dark current.3

In this presentation, I will discuss the synthesis of PEA2Cs2Pb3Br10/CsPbBr3 perovskite heterostructure microcrystals (~20-40 μm) and the influence of precursor composition on the formation of distinct crystalline phases.4 Further, I will throw light on the impact of using heterostructures for X-ray detection and how their strategic use minimizes the trade-off between sensitivity and dark current. Furthermore, the structural and optical characterization of these heterostructures will be presented to elucidate the heterostructure properties. Their potential for X-ray detectors will also be demonstrated through proof-of-concept X-ray detector devices.

Compared to their individual constituents, the heterostructures achieve a high sensitivity of 18603.25 μC/Gycm2 and a low limit of detection of 18 μGy/s. This improvement is attributed to more efficient charge-carrier dynamics at the heterointerface and suppressed ion migration.

These results highlight quasi-2D/3D perovskite heterostructures as promising candidates for next-generation, high-performance X-ray detectors.

1. Kim, S. et al. Recent advancements and challenges in highly stable all-inorganic perovskite solar cells. Mater. Today Electron. 10, 100127 (2024).
2. Clinckemalie, L. et al. Challenges and Opportunities for CsPbBr3 Perovskites in Low- and High-Energy Radiation Detection. ACS Energy Lett. 6, 1290–1314 (2021).
3. Zhang, X. et al. Solution‐Grown Large‐Sized Single‐Crystalline 2D/3D Perovskite Heterostructure for Self‐Powered Photodetection. Adv. Opt. Mater. 8, 2000311 (2020).
4. Li, Q. et al. Bifunctional polymer assisted growth of crack-free thick perovskite films for flexible X-ray detection. J. Mater. Chem. C 10.1039.D6TC00075D (2026) doi:10.1039/D6TC00075D.

Speaker: Mr Singh Rajveer (KU Leuven)

24 Interface and Architecture Optimization in PbPc-based Organic Photodetectors

Organic photodetectors (OPDs) are appealing candidates for medical dosimetry because of to their tissue equivalence. However, their low detection efficiency for high-energy photons hinders their use in radiology. In this work, we investigate the use of lead phthalocyanine (PbPc), a small-molecule semiconductor with optical absorption in the visible and near-infrared (NIR). The central heavy atom in PbPC can enhance X-ray attenuation when the material is used in thin-film OPDs.
The study initially focuses on interface engineering to optimize extraction and reduce recombination. The influence of different hole transport layers (HTLs), as well as their combination in bilayers, was evaluated. Injection layers such as PEDOT:PSS and molybdenum oxide ($MoO_{3}$) were also investigated, and found to reduce dark currents and overall performance parameters.
The effect of the choice of electron transport layers (ETLs) was studied as well. Materials such as $C_{60}$, BCP, $SnO_x$ were evaluated as top ETLs, leading to a further improvement in efficiency. In this work we will discuss also the difference between bilayer and bulk heterojunctions (BHJ), and their implication in the design of efficient optical sensors.

Speaker: Alejandra Silva Mayo (Universidad de Valencia)

25 Practical Pitfalls in Time-of-Flight Measurements on Halide Perovskites

Time-of-flight (ToF) measurements are widely used to probe charge transport properties in halide perovskites, including carrier mobility and trapping dynamics. While the technique is conceptually straightforward, its practical implementation is often affected by a range of experimental artifacts that can lead to significant misinterpretation of the results.
In this contribution, we present a practical guide to reliable ToF measurements on perovskite materials, based on common failure modes observed in real experiments. We demonstrate how excessive excitation density can distort signals via space-charge effects or plasma-like behavior, leading to incorrect transit time extraction. In thin samples and flexible detector structures, the measured current waveforms are often strongly shaped by device capacitance and the measurement circuit, requiring careful deconvolution or modeling of the instrument response.
We further discuss time-dependent changes in perovskite samples, emphasizing the need for control measurements and stability checks during data acquisition. Particular attention is given to solution-grown materials, where interfacial effects can produce apparent transit times unrelated to bulk transport, often resulting in overestimated mobilities.
Finally, we briefly address the role of ionic space charge and its impact on internal electric fields during measurement. The goal of this work is not to introduce a new method, but to provide a set of practical guidelines and diagnostic tools that help distinguish genuine transport phenomena from measurement artifacts.

Speaker: Marián Betušiak (Faculty of Mathematics and Physics, Charles University)

26 Study of inhomogeneities in CPB perovskite sample

Lead halide perovskites are promising materials for the development of technologies such as radiation detectors, solar cells, and light-emitting diodes. Their advantages include a high absorption coefficient over a broad spectral range, attributed to the large atomic numbers of their constituent elements, a high mobility–lifetime product, long carrier diffusion lengths, low fabrication costs, and high defect tolerance. However, their practical application is limited by several drawbacks, including gradual degradation of contacts, instability under continuous illumination, and high dark current or environmental instability [1, 2, 3].

In this work, cesium lead bromide (CsPbBr$_3$, CPB), an all-inorganic perovskite grown by the Bridgman method, was studied. The 1.7 mm thick samples were prepared with evaporated square Au electrodes with dimensions of 10 mm x 10 mm. Furthermore, the cathode was a full electrode, while the anode consisted of an 8 mm x 8 mm central electrode (CE), a guard ring (GR) structure with a thickness of 0.5 mm, and a 0.5 mm gap between the CE and GR structure. Regions with inhomogeneities in the sample were observed in charge collection and photocurrent. Two measuring techniques were performed:

1. TCT (Transient Current Technique) measurement of a 2D map of charge collection efficiency using a green laser

2. photocurrent 2D mapping measurement using a green laser diode

In both cases, the individual responses of CE and GR were measured simultaneously.

The presence of inhomogeneities causes uneven charge collection in various regions of the sample. This further imposes broadening of the detected spectral lines, which decreases the resolution of the perovskite detectors. The origin of the inhomogeneities, or why they are concentrated almost exclusively at the edge of the sample, is still under research. It is proposed that during the growth of the CPB crystal in a quartz ampoule using the Bridgman method, a phase transition occurs in which the volume of the elementary cell increases. This imposes strain on the crystal, resulting in the formation of diagonal stripes (twins) in the crystal. When an external electric field is applied, the charge carriers preferentially drift along these stripes in a diagonal direction, thus accumulating at the edge of the sample.

[1] J. Wei et al., Halide lead perovskites for ionizing radiation detection, Nature Communications, 2019.

[2] S. Shrestha et al., X-ray Detectors Based on Halide Perovskite Materials, Coatings, 2023.

[3] K. Pekárková, R. Grill, M. Ledinský, et al., Light-Induced Surface Recombination Suppression, Carrier Lifetime Improvement, and Deep Defect Formation in Lead Halide Perovskites, Laser Photonics Rev19, no. 18, 2025.

Speaker: Mr Samuel Kačenga (Institute of Physics of Charles University)

Friday 12 June

Session 5: Hybrid Perovskite Materials

27 Advances in Perovskite Scintillators at the University of Milano-Bicocca: From High-Z Sensitization to Cooperative Emission Beyond Classical Limits

Lead-halide perovskite nanocrystals (LHP NCs) are emerging as a promising platform for next-generation scintillators, combining high light yield with sub-nanosecond timing and access to collective quantum-optical regimes. This talk presents recent advances obtained at the University of Milano-Bicocca in both material design and assembly.By integrating CsPbBr3 nanocrystals into high-Z and mesostructured hosts, we successfully suppress defect-mediated degradation while preserving ultrafast radiative kinetics. Sensitization with heavy oxide nanoparticles, such as HfO2, enhances energy deposition and charge generation under ionizing radiation, effectively decoupling absorption from emission. Furthermore, exploiting weak quantum confinement yields giant oscillator strengths that successfully reconcile brightness and speed. At higher levels of structural ordering, nanocrystal superlattices exhibit scintillation superfluorescence, converting stochastic ionization cascades into deterministic picosecond light bursts.To tackle the ubiquitous issue of self-absorption in LHP NCs, we synthesized multilayered perovskite nanoplatelets that combine an ultrafast decay time with a large Stokes-shifted emission, demonstrating a valuable platform for LHP scintillator detectors. When integrated into photonic cavities, these systems exhibit Purcell-enhanced scintillation with accelerated timing and enhanced efficiency, marking a major step toward photonic-enhanced scintillator platforms enabled by LHP emitters. Finally, we demonstrate that plasmonic coupling between metallic nanoparticles and polyconjugated emitters sensitized by high-Z particles enables Purcell-enhanced scintillation with accelerated radiative decay.Together, these advances point toward nanoscintillators with light yields and timing resolutions approaching a few tens of picoseconds, carrying profound implications for time-of-flight imaging, high-energy physics, and precision dosimetry.

Speaker: Prof. Sergio Brovelli (Milan Bicocca University)

28 Bifunctional Polymer-Assisted Growth of Crack-Free Thick Perovskite Films for Flexible X-ray Detection

The expanding use of perovskite materials in flexible optoelectronics has sparked growing interest in their application for flexible X-ray detectors. However, developing flexible, lead-free perovskite devices remains challenging because achieving the film thickness required for strong X-ray absorption typically leads to cracking and poor device reliability.[1]
In this presentation, I will introduce a bifunctional polymer-guided crystallization strategy to resolve the intrinsic trade-off between thickness, mechanical integrity, and charge transport continuity in Cs₂AgBiBr₆ thick films.[2] P123 is composed of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG), to simultaneously control crystallization and enhance the mechanical integrity of lead-free Cs₂AgBiBr₆ thick films. We demonstrated that PEG modulates precursor coordination and intermediate-phase evolution, suppressing uncontrolled nucleation, while the PPG prevents excessive Ag⁺ binding and stabilizes uniform long-range crystal growth. Together, these two molecular interactions establish a self-regulated crystallization environment that produces uniform, highly ordered, and mechanically resilient Cs₂AgBiBr₆ thick films approaching 100 µm.
The resulting P123-modified Cs₂AgBiBr₆ detectors deliver a remarkable X-ray sensitivity of 244.71 μC Gy⁻¹ cm⁻² under a low bias of 50 V mm⁻¹, more than twice that of unmodified devices based on Cs2AgBiBr6 microcrystals.[3] Moreover, the detectors maintained over 70% of their initial sensitivity under small bending radii and over 80% after 500 bending cycles, exhibiting outstanding fatigue endurance and long-term stability over a 60-day period, in contrast to the pronounced degradation seen in pristine Cs₂AgBiBr₆ devices. This study establishes a polymer-guided design paradigm for fabricating lead-free, flexible, and scalable perovskite-based radiation detectors.[2]

[1] I. López-Fernández, D. Valli, C.-Y. Wang, S. Samanta, T. Okamoto, Y.-T. Huang, K. Sun, Y. Liu, V. S. Chirvony, A. Patra, J. Zito, L. De Trizio, D. Gaur, H.-T. Sun, Z. Xia, X. Li, H. Zeng, I. Mora-Seró, N. Pradhan, J. P. Martínez-Pastor, P. Müller-Buschbaum, V. Biju, T. Debnath, M. Saliba, E. Debroye, R. L. Z. Hoye, I. Infante, L. Manna and L. Polavarapu, Advanced Functional Materials 2024, 34, 2307896.
[2] Q. Li, D. Valli, R. V. Brande, G. Rizzi, J. Hofkens, W. Qu and E. Debroye, Journal of Materials Chemistry C 2026.
[3] L. Clinckemalie, R. A. Saha, D. Valli, E. Fron, M. B. J. Roeffaers, J. Hofkens, B. Pradhan and E. Debroye, Advanced Optical Materials 2023, 11, 2300578.

Speaker: Qianrui Li (KU Leuven)

29 Defect-Mediated Scintillation in Mixed-Phase CsPbBr3/Cs4PbBr6 Perovskites and Their Integration into 3D-Printed Plastic Scintillators

Scintillation detectors are essential in high-energy physics, medical diagnostics, and radiation monitoring, where fast and efficient conversion of ionizing radiation into visible light is required. Lead halide inorganic perovskites have recently emerged as promising next-generation scintillators due to their high atomic number, strong X-ray attenuation, high radioluminescence yield, and intrinsically fast emission. Among them, the three-dimensional (3D) perovskite CsPbBr3 has been widely investigated for scintillation applications. In contrast, the zero-dimensional (0D) phase Cs4PbBr6 exhibits peculiar defect-mediated emission behavior whose role in scintillation remains unclear and debated. Although mixed-phase systems containing both structures are frequently obtained during synthesis, the specific contribution of the 0D phase to scintillation performance has not been systematically explored.

A simple, reproducible solvent–antisolvent synthesis route is developed to deliberately modulate the relative proportion of the 3D and 0D phases within polycrystalline cesium lead bromide powders. The method relies on controlled incremental additions of water during synthesis, which selectively promote the formation of the 3D phase while preserving a tunable fraction of the 0D one. This strategy enables a systematic investigation of how the coexistence and ratio of CsPbBr3 and Cs4PbBr6 affect scintillation behavior, offering a unique opportunity to clarify the functional role of the 0D phase.

Scintillation measurements under X-ray excitation reveal that samples synthesized with low water volumes, corresponding to a higher fraction of the 0D phase, exhibit increased scintillation yield combined with an ultrafast decay time. These findings indicate that defect states associated with the 0D structure actively participate in radiative recombination processes under ionizing radiation. Cathodoluminescence and temperature-dependent radioluminescence analyses further support a defect-driven scintillation mechanism, highlighting the interplay between structural confinement and defect chemistry in determining emission dynamics. This provides new insight into the emission mechanism of Cs4PbBr6 and establishes design principles for optimizing mixed-phase perovskites for radiation detection.

Building on these materials insights, additive manufacturing is exploited for the first time to fabricate scintillators with complex three-dimensional geometries based on perovskite materials. An innovative nanocomposite is developed by dispersing Cs4PbBr6 powders into a thermosetting photocurable resin, enabling processing via stereolithography. The high-Z lead-based perovskite filler ensures efficient interaction with ionizing radiation and conversion into visible light, while the polymer matrix provides printability, mechanical stability, and environmental protection.

Rheological and photopolymerization studies demonstrate that the inclusion of the perovskite filler does not significantly alter the viscosity, flow behavior, or curing kinetics of the resin, preserving its suitability for high-resolution stereolithographic printing. Optical and radioluminescence characterizations confirm that embedding the perovskite within the polymer matrix does not compromise its emission properties. Encapsulation enhances environmental stability, protecting the perovskite from moisture and degradation while maintaining a fast scintillation response.

This combined materials and manufacturing approach introduces a new class of 3D-printable plastic scintillators that merge the outstanding radiation detection capabilities of inorganic lead halide perovskites with the versatility and scalability of additive manufacturing. The results not only deepen the understanding of defect-mediated scintillation mechanisms in mixed-phase perovskites but also demonstrate a practical pathway toward customizable, stable, and high-performance scintillation devices for advanced radiation sensing applications.

Speaker: mario calora

30 Impact of Dose-Rate Dependence on the Accuracy of Perovskite Radiation Dosimeters

Hybrid halide perovskites have recently emerged as highly promising materials for radiation detection, enabling efficient sensing of a broad spectrum of radiation, from UV–visible photons to high-energy X-rays, γ-rays, and charged particle beams. Significant advances in device engineering and material optimization have led to remarkable performance in terms of sensitivity and charge collection efficiency. However, despite these achievements, a comprehensive understanding of the fundamental detection mechanisms and their impact on device behavior under realistic operating conditions remains incomplete. In particular, the dependence of the detector response on the dose rate, although frequently observed, has been largely overlooked and is often not considered a limiting factor.
In this work, we investigate the dose-rate dependence of hybrid perovskite-based radiation detectors and demonstrate its critical impact on their performance as dosimeters and beam monitors. Using a flexible 2D perovskite (PEA₂PbBr₄) thin-film photoconductor as a model system, we systematically analyze the detector response under different irradiation modalities, including UV light, X-rays, γ-rays, and proton beams. While the collected charge is found to scale linearly with the total delivered dose, the photocurrent exhibits a pronounced sublinear dependence on the dose rate or photon flux across all investigated radiation sources. This universal behavior highlights a common underlying physical mechanism governing the detection process.
We show that such dose-rate dependence leads to significant distortions in practical applications. In clinically relevant scenarios, including external beam radiotherapy and brachytherapy, the non-linear response results in misestimation of dose distributions, affecting both transversal beam profiling and depth-dose reconstruction. In proton therapy conditions, this manifests as deformation of the beam tails and underestimation of the Bragg peak amplitude, while in γ-ray brachytherapy it leads to systematic deviations in percentage depth dose measurements. These effects are particularly critical given that medical dosimetry requires a flat and dose-rate-independent response to ensure accurate and reliable dose assessment.
To elucidate the origin of this behavior, we develop a physical model based on trap-assisted carrier dynamics in the perovskite active layer. The model accounts for the interplay between carrier trapping, emission, and recombination processes, and introduces the injected charge density (ICD) as a unifying parameter to describe different irradiation conditions. By considering two distinct trap distributions with different activation energies, the model successfully reproduces both the steady-state sublinear response and the temporal evolution of the photocurrent under varying irradiation regimes. The analysis reveals that deep trap states dominate the response at low ICD, enhancing photoconductive gain, while shallower traps become active at higher injection levels, leading to gain compression.
Finally, we propose and experimentally validate a calibration methodology that corrects for the dose-rate-induced distortions, allowing an accurate reconstruction of proton beam profiles in agreement with reference dosimeters.
Overall, this work provides a comprehensive framework for understanding and mitigating dose-rate effects in perovskite radiation detectors, highlighting both a fundamental limitation and a pathway toward their reliable implementation in real-world dosimetric applications.

L. Basirico’ et al, under revision, 2026

Speaker: Laura Basiricò

10:45 Coffee Break

Session 6: Other Perovskite Materials

31 Understanding and Advancing Perovskite Materials toward Stable and Efficient Optoelectronics

Metal halide perovskites have emerged as a highly promising class of semiconductors for optoelectronic applications due to their exceptional light absorption, tunable emission, and efficient charge transport. These cost-effective materials have demonstrated an unprecedented rise in solar power conversion efficiency, surpassing 25% within a decade, outpacing conventional silicon photovoltaics. However, fundamental insights into their intrinsic photophysical properties remain incomplete, yet are crucial for further performance enhancements. Additionally, while the impressive efficiency of novel perovskite materials is often emphasized, their long-term stability is equally vital for practical implementation.[1,2]

In this talk, I will present the development of perovskite systems with diverse compositions, structures, and morphologies using various synthesis strategies. By employing advanced spectroscopic techniques, we elucidate the interplay between crystalline structure and charge carrier dynamics that dictate their optoelectronic performance.[3,4] Additionally, photoluminescence (PL) microscopy imaging is being exploited correlating materials’ photochemistry and intrinsic defects to optoelectronic device performance, providing direct insight into their function in real-world applications.[5,6] I will demonstrate how chemical micro-engineering can optimize perovskite stability and functionality, with a focus on improving X-ray detection performance.[7,8] Finally, I will present strategies for fabricating high-quality flexible photoactive layers [9], including controlled film deposition, as critical components for next-generation stable optoelectronics.

References
[1] Jin, H.; Zeng, Y.; Steele, J.A.; Roeffaers, M.B.J.; Hofkens, J.; Debroye, E. Phase Stabilization of Cesium Lead Iodide Perovskite toward Efficient Optoelectronic Devices. NPG Asia Mater. 2024, 16, 24
[2] Jin, H.; Debroye, E.; Keshavarz, M.; Scheblykin, I.; Roeffaers, M.; Hofkens, J.; Steele, J. It’s a Trap! On the Nature of Localised States and Charge Trapping in Lead Halide Perovskites. Mater. Horiz. 2020, 7, 397
[3] Jin, H.; Steele, J.; Cheng, R.; Parveen, N.; Roeffaers, M.; Hofkens, J.; Debroye E. Experimental Evidence of Chloride-Induced Trap Passivation in Lead Halide Perovskites through Single Particle Blinking Studies. Adv. Opt. Mater. 2021, 2002240
[4] Yuan, H.; Debroye, E.; Bladt, E.; Lu, G.; Keshavarz, M.; Janssen, K.; Roeffaers, M.; Bals, S.; Sargent, E.; Hofkens, J. Imaging Heterogeneously Distributed Photo‐Active Traps in Perovskite Single Crystals. Adv. Mater. 2018, 30, 13, 1705494
[5] Seth, S.; Louis, B.; Asano, K.; Van Roy, T.; Roeffaers, M.B.J.; Debroye, E.; Scheblykin, I.G.; Vacha, M.; Hofkens, J. Unveiling the Local Fate of Charge Carriers in Halide Perovskite Thin Films via Correlation Clustering Imaging. Chem. & Biomed. Imaging 2025, 3, 4, 244
[6] Mukherjee, A.; Reynaerts, R.; Pradhan, B.; Seth, S.; Rösch, A.T.; Banerjee, T.; Chouhan, L.; Jin, H.; Sternemann, C.; Paulus, M.; Leoncino, L.; Mali, K.S.; De Feyter, S.; Roeffaers, M.B.J.; Meijer, E.W.; Hofkens, J.; Debroye, E. Machine learning for microscopy data analytics targeting real-time optical characterization of semiconductor nanocrystals. Nature Commun., 2026, 10.1038/s41467-026-68939-7
[7] Valli, D.; Vanden Brande, R.; Herreman, V.; Li, Q.; Romolini, G.; Chen, J J.-K.; Shameem, K.M.M; Sun, L.; Zhao, Q.; Pradhan, B.; Hofkens, J.; Debroye, E. Noble Metal Doping in Lead-Free Double Perovskite Single Crystals: Achieving Near-Infrared to X-ray Broadband Photodetection. Small Science, 2025, 5, 8, 2500135
[8] Keshavarz, M.; Debroye, E.; Ottesen, M.; Martin, C.; Zhang, H.; Fron, E.; Küchler, R.; Steele, J.; Bremholm, M.; Van de Vondel, J.; Wang, H.; Bonn, M.; Roeffaers, M.; Wiedmann, S.; Hofkens, J. Tuning the Structural and Optoelectronic Properties of Cs2AgBiBr6 Double Perovskite Single Crystals Through Alkali Metal Substitution. Adv. Mater. 2020, 32, 40, 2001878
[9] Li, Q.; Valli, D.; Vanden Brande, R.; Rizzi, G.; Hofkens, J.; Qu, W.; Debroye, E. Bifunctional Polymer Assisted Growth of Crack-free Thick Perovskite Films for Flexible X-ray Detection. J. Mater. Chem. C. 2026, 10.1039/D6TC00075D

Speaker: Elke Debroye (Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001, Heverlee, Belgium)

32 Metal Halide Rb2AgX3 (X = Cl, Br): Pb-Free Scintillator Materials for Ionising Radiation Detection

Rb-based metal halide materials possess large attenuation coefficients and bright luminescence making them suitable as scintillators for X-ray detection. Here, we present the first report of an optimised anti-solvent synthesis method enabling gram-scale preparation of phase-pure Rb2AgX3, (X = Cl, Br) metal halides, which show broadband emission centred at 585 nm and 514 nm, respectively. We have identified solvent selection criteria that are broadly applicable to the synthesis of a wider variety of perovskite materials. This approach offers several advantages: reduced reaction temperatures, shorter reaction times, enhanced purity, and increased yields. Collectively, these improvements contribute to a more sustainable and scalable synthesis route.
Rb2AgX3, (X = Cl, Br) metal halides report fast radiative recombination with typical decay times of sub-10 ns. Optical and radioluminescence measurements revealed halide-specific emission pathways with Rb2AgCl3 displaying superior emission intensities, whereas Rb2AgBr3 consistently elicited a stronger X-ray induced response. High pressure XRD studies measured bulk crystal moduli indicating that the Rb2AgCl3 crystal structure has a stiffer lattice than the Rb2AgBr3 analogue. Compressing pellets of polycrystalline Rb2AgX3 over a range of pressures (both at room temperature and 70 C) confirmed this lattice stiffness trend and allowed for improvements in material densification and optical clarity at thicknesses of > 250 μm. The X-ray response of these pellets improved with increasing pressure for the bromide analogue underscoring the importance of microstructural control in enhancing scintillation efficiencies.

Speaker: Carol Crean

33 Compositional design of multi-cation vacancy-ordered double perovskites by mechanosynthesis for radiation detection

Halide perovskites based on the ABX3 structure have recently gained significant attention for emerging optoelectronic applications, including low-dimensional phases, double perovskites (A2BB’X6), and vacancy-ordered derivatives (A2BX6) [1]. In this context, vacancy-ordered double perovskites (VO-PVSKs) offer an alternative by replacing lead with high-Z elements, which are potentially less toxic while still preserving strong X-ray absorption properties. Their fully inorganic composition suggests improved resilience under high-energy radiation compared to hybrid halide perovskites, and their A2BX6 framework provides wide compositional flexibility, allowing access to a variety of tetravalent B-site cations.
In this work, we report a scalable wet mechanochemical route for the preparation of vacancy-ordered halide perovskites as a platform for compositional screening in systems based on Hf4+, Zr4+, and Te4+ cations. Across these compositions, broadband self-trapped exciton (STE) emission with large Stokes shifts is observed. Notably, binary and ternary mixtures show an enhanced yellow emission associated with Te4+ composition, suggesting the presence of an energy cascade process between different octahedral environments. We used pair distribution function (PDF) and Raman spectroscopy to study the local order of these compositions, indicating locally complex structures that may be relevant for radiation tolerance through high-entropy mixing. In situ X-ray total scattering experiments reveal a stable structural response up to ~300 ºC, while radioluminescence measurements under synchrotron X-ray excitation, as well as electron and alpha particle irradiation, confirm efficient emission under ionising radiation. Under continuous synchrotron X-ray exposure, the radioluminescence signal retains ~63% of its initial intensity up to doses of ~5kGy, corresponding to approximately 500k CT scans. These results point towards an accessible materials platform for emerging detection applications, including ion detection and space technologies.

References:
[1] T. Wang et al., Advances in Metal Halide Perovskite Scintillators for X-Ray Detection,Nano-Micro Lett., 17, 275, 2025, doi: 10.1007/s40820-025-01772-7.
[2] S. Fernández-Muñoz et al., Mechanochemical synthesis of B-site cation mixed vacancy-ordered chloride perovskites with enhanced stability, in preparation.

Speaker: Sol Fernández Muñoz (Universidad de Sevilla)

34 Compressed Semiconductors for X-ray Detection: Achievements and Perspectives from Bi-Based Hybrids to Lead-Free Double Perovskites and Binary Chalcogenides

Compressed semiconductors have recently emerged as a promising materials platform for scalable, low-cost, and high-performance X-ray detection, offering an attractive alternative to conventional single-crystal technologies. By enabling dense detector architectures through powder compaction, this approach opens new opportunities for simplified device fabrication while maintaining excellent optoelectronic functionality.
In this talk, we present recent progress in developing compressed direct X-ray detectors based on several classes of materials, highlighting both key achievements and future perspectives.
First, we discuss our pioneering work on bismuth-based hybrid materials, which demonstrated that compacted polycrystalline semiconductors can achieve efficient X-ray detection with remarkable sensitivity and operational stability. These results established compressed Bi-based materials as a viable detector concept, revealing the important role of defect tolerance, high atomic number constituents, and pressure-induced improvements in charge transport and interparticle connectivity.
Building on this concept, we extend the compressed detector strategy to lead-free double perovskite materials, focusing on environmentally benign alternatives with enhanced chemical robustness. We highlight recent results on vacancy-ordered and double perovskite Cs₂AgBiBr6, showing how compositional engineering combined with mechanical densification and sintering can yield stable detectors with encouraging sensitivity, low dark currents, and promising long-term performance. These studies underline the broader potential of perovskite-inspired compounds for sustainable radiation detection.
Finally, we present emerging results on binary semiconductor pellets based on Antimony trisulfide, a highly attractive earth-abundant absorber combining strong X-ray attenuation, benign composition, and favorable semiconductor properties. We show how compressed Sb₂S₃ detectors provide a new pathway toward simple and scalable detector architectures, while also raising important questions regarding grain-boundary transport, trap-mediated processes, and optimization of pressure-assisted microstructures.
Across these material systems, we identify common principles governing compressed detector operation, including particle interfaces as functional transport pathways, pressure-induced tuning of electronic properties, and the interplay between microstructure, ionic/electronic transport, and detector metrics. We discuss how these insights can guide the next generation of compressed detectors toward higher sensitivity, lower detection limits, and improved temporal response.
Looking forward, compressed semiconductors may evolve from a proof-of-concept concept into a versatile detector platform, particularly when combined with mechanochemical synthesis, compositionally complex materials, and scalable pellet-processing routes. We outline future directions toward fully lead-free, high-performance, and manufacturable X-ray detectors, emphasizing the opportunities of compressed materials to bridge fundamental materials discovery with practical radiation sensing technologies.

Speaker: Prof. Olena Maslyanchuk (Department Solution-Processing of Hybrid Materials and Devices, Helmholtz-Zentrum Berlin)

35 Final Remarks

13:00 Lunch