Investigation On Preparation Of Perovskite Layer And Electron-transport Materials For Perovskite Solar Cells

In organic-inorganic hybrid halogen perovskite solar cell,the electron transport material and its interface with absorption layer play an important role on the photoelectrical conversion efficiency.The mesoscopic structures of the electron-transport layer will directly influence the growth of perovskite layer,whose microstructures are crucial for the stability and life-span of solar cells.One dimensional TiO2 nano arrays have expected to be the alternative electron transport materials for solar cells according to its highly ordered structure and efficient charge carrier transport,and become a hot topic in materials science.In this work,the layer of TiO2 nanorod arrays grown by hydrothermal method was used as the electron transport material,and a compact Ti02 thin film deposited on FTO substrate by magnetron sputtering as the blocking layer.It was found that the compact TiO2 layer can effectively inhibit the recombination of electron-hole pairs at interface.The perovskite layers were prepared via one-step or two-step chemical solution deposition.The quality of the two-step prepared perovskite layer is much better than the one-step one,and the corresponding short-circuit current and efficiency are greatly enhanced for the former.While the quality of the modified two-step prepared perovskite layer is comperatively better,and the corresponding efficiency was greatly enhanced at some level.The main results are as follows:1?The best annealing temperature of one-step prepared perovskite layer was 100?,and the best electron transport layer structure was 50nm compact TiO2 thin film deposited by magnetron sputtering and 500nm TiO2 nanorod arrays grown by hydrothermal method.2?The quality of the two-step prepared perovskite layer is much better than the one-step one,it can effectively enhance the number of electron-hole pairs and inhibit the recombination of electron-hole pairs at interface,so as to increase the short-circuit current and efficiency,the photoelectric conversion efficiency of the optimized solar cell reached 3.69%.3?By investigating how dipping time and evaporation weight of PbI2 affect the solar cell when prepared CH3NH3PbI3 as absorbing layer via modified two-step method,it was found that the quality of prepared CH3NH3PbI3 layer was much better than chemical solution two-step method when we evaporated 0.15g PbI2 and dipped 30min,the optimized photoelectric conversion efficiency reached 5.92%.4?We preliminary investigated the surface potential difference of CH3NH3PbI3/TiO2 interface by Kelvin Probe Force Microscopy.The surface potential difference between CH3NH3PbI3 and TiO2 was 270mV in the dark,while the difference was 554mV under illumination.