Highly Stable Benzylamine-Copper-Bromide Perovskite Light Absorber And The Photovoltaics Devices

Organic-inorganic hybrid perovskites for photovoltaic cells(PVSCs)have drawn enormous attention of researchers in recent years due to their excellent optical and electronic properties.So far,the power conversion efficiency(PCE)of perovskite solar cells has already reached over 22%.However,the toxicity hazardous Pb and the instability of Pb-based halide perovskite materials may eventually hamper the large-scale industrial application of PVSCs.To solve these critical problems,we develop a lead-free,highly stable(C6H5CH2NH3)2CuBr4(PMA2CuBr4)perovskite light-harvesing material,study its humidity stability,heat stability and ultraviolet-light stability to investigate its potential application in solar cell.The main contents and results are summarzed as follows:(1)The crystal structure and photoelectric properties of PMA2CuBr4 perovskiteThe PMA2CuBr4 perovskite were synthesized by chemical solution method,and PMA2CuBr4 perovskite films were prepared by sol-gel process.The PMA2CuBr4 microstructure was investigated by Power X-ray diffraction(XRD)and Energy-dispersive spectroscopy(EDS).The optical properties were studied by UV-vis spectroscopy(UV-vis)and Photoluminescence spectroscopy(PL).The results indicated that PMA2CuBr4 perovskite is 2D layered structure,the ratio of Cu and Br is about 1:4.PMA2CuBr4 thin film exhibited a Eg of～1.81 eV,a high absorption coefficient of 1 ×105 cm-1 at 539 nm,a PL peak of～660 nm(1.87 eV)and the charge carrier lifetime of 3.02 ns.(2)The stability characterization of PMA2CuBr4 perovskiteThe humidity-stability,heat-stability and ultraviolet light tolerance were investigated by XRD,UV-vis and Thermo gravimetric analysis(TGA).The results showed that no degradation occurs during the 7 days and after UV illumination for 14 h.UV-vis spectrum results exhibits no obvious changes during this period.The XRD patterns remain nearly the same even after 6 h of heating PMA2CuBr4 film on hotplate at 100 ℃ and high thermal-stability with a beginning of weight loss at～160 ℃.(3)The photovoltaic properties of PMA2CuBr4-based solar cellsThe PMA2CuBr4-based light absorber was applied in planar and mesoporous solar cell.The photovoltaic properties of PMA2CuBr4-based solar cell were measured by PL spectrum.A preliminary PCE of～0.2%was achieved.The poor photovoltaic properties of PMA2CuBr4 solar cell can be attributed to the intrinsic layered structure of PMA2CuBr4 perovskite.The low carrier mobility and larger exciton binding energy hamper the PMA2CuBr4 perovskite solar cell performance because of layered perovskite structure.Besides,the performance of the device was limited by the poor photogenerated carrier extraction efficiency.