Deposition of TiO2-Coated CsPbBr3 Perovskite Heterostructure Thin Film

Abstract

All-inorganic lead halide perovskite quantum dots have been emerged in recent years for optoelectronic and photovoltaic devices due to their excellent optical properties. In this work, surface coating was carried out by titanium dioxide (TiO2) to coat on the surface of CsPbBr3 PQDs to improve the stability and charge separation property. The FTIR spectra confirmed the formation of TiO2 with an amorphous phase (am-TiO2). The crystallite size of CsPbBr3/am-TiO2 QDs composite was increased to be 13.30 nm from 12.65 nm of CsPbBr3. A slightly decrease of energy bandgap was found compare to CsPbBr3 QDs owing to quantum confinement effect. The results also show the enhancement of light absorption in the visible region and charge separation property examined by UV-visible and PL spectroscopy, respectively. The ligand removal process was also investigated by centrifugation of the colloidal QDs with methyl acetate. 2 times washing cycles is the optimal number of times to remove surface ligand due to large amount of ligands were removed and shows less defect in QDs thin film. Finally, CsPbBr3/am-TiO2 QDs composite was deposited as an absorber layer for the Schottky solar cell device by spin coating technique. The CsPbBr3/am-TiO2 QDs composite-based solar cell device shows large fill factor up to 86.43% and the best power conversion efficiency (PCE) is 0.00032%, which is about 6 times higher than that of bare CsPbBr3 QDs device.