Siam Physics Congress 2018

Surface Modification of TiO2 for Efficiency Enhancement in Perovskite Solar Cells

21 May 2018, 15:45

15m

๊Uthai Thani Room

Oral Surface, Interface and Thin Film A5: Nanoscale and Surface

Speaker

Mr Kittiwut Chaisan (Department of Physics and Materials Science, Faculty of Science, Chiang Mai University)

Description

Surface modification of titanium dioxide (TiO${}_2$) substrates was performed to enhance efficiency of perovskite solar cells efficiency by inserting small organic molecules between TiO${}_2$ electron transporting layer and CH${}_3$NH${}_3$PbI${}_3$ perovskite layer. TiO${}_2$ substrates were immersed into a solution of amino propionic acid (APA) or amino benzoic acid (ABA) in order to tune up and improve surface quality which leads to changes in PbI${}_2$ and CH${}_3$NH${}_3$PbI${}_3$ perovskite morphology and structure. Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopes (FE-SEM), X-ray diffraction (XRD) and open-circuit voltage-decay (OCVD) were performed to characterize material and device properties. It was found that introduced organic molecules change the PbI${}_2$ precursor morphology which attributes to different trend of efficiency enhancement. Small cracks spreading through PbI${}_2$ film coated on TiO${}_2$/APA were observed. These cracks promote PbI${}_2$ transformation to CH${}_3$NH${}_3$PbI${}_3$ perovskite when reacts with CH${}_3$NH${}_3$I. The device with APA treatment show the improvement in power conversion efficiency from 6.23% for untreated TiO${}_2$ condition to 7.78%. In addition, the OCVD analysis revealed that charge carrier lifetime of APA-treated device is significantly longer than that of the untreated device. These imply that this simple surface modification by small organic molecules could improve efficiency of perovskite solar cells.