The Effect Of Doping Density On Device Performance Of Polymer Solar Cells And Study On Polarity-switchable Perovskite Photovoltaic Devices

High efficient convert solar energy into electricity is the most effective and direct way to solve the energy crisis, and photovoltaic industry increasingly get people’s attention in recent years. Thin film solar cells has become the hotspot to develop clean energy and solve the energy crisis due to its great application potential and low price advantage, organic polymer solar cells and perovskites solar cell are the most promising and representative. In this paper, the work mainly on the effect of detect density on device performance of polymer solar cells based on the system of poly (3, hexyl thiophene:fullerenes (P3HT:PCBM) and study on polarity-switchable perovskite photovoltaic devices:1. The change in doping density in P3HT:PCBM based polymer solar cells (PSCs) with different processing solvents and with/without post-fabrication thermal treatment is investigated with capacitance-voltage measurement and optical microscopic imaging. Direct links between the doping density and the performance of the PSCs, specifically the short-circuit current (Jsc) and open-circuit voltage (Voc), are observed. Lower doping density leads to a wider depletion region, which is beneficial for carrier collection. The agreement between the calculation and the experiment suggests that the Voc increases monotonically with increasing doping densities in the PSCs. Evolution in surface morphology suggests that both slow drying and thermal treatment facilitate the phase-separation and crystallinity of P3HT and PCBM, leading to low defect density and thus low p-type doping density.2. We developed an novel polarity-switchable photovoltaic device in the structure of ITO/PEDOT:PSS/CH3NH3PbI3/Mo03/Al. It is proved that a large amount of mobile ions exist in organic-inorganic halide perovskites. The accumulated ions at the interface change the band bending of the perovskites semiconductor, the change of bias’direction will change the polarity of accumulated ions at the interface, leading to polarity-switchable photovoltaic devices. The interface charge significantly influences the function and performance of perovskite devices. The current-voltage hysteresis in perovskite solar cells is caused by the accumulation and relaxation of the interface charge.