Mixed (5-AVA)xMA1−xPbI3−y(BF4)y perovskites enhance the photovoltaic performance of hole-conductor-free printable mesoscopic solar cells

We report on a simple one-step solution processing strategy to fabricate new stable mixed cation/mixed halide (5-AVA)xMA1−xPbI3−y(BF4)y perovskite solar cells. The results showed that the power conversion efficiency (PCE) of the optimized mixed (5-AVA)0.034MA0.966PbI2.95(BF4)0.05 perovskite solar cells was substantially increased to 15.5% with a remarkably high VOC of 0.97 V. We have analyzed different mixed perovskites focusing on the characterization of the charge recombination by means of intensity-modulated photovoltage spectroscopy. In addition, our study discloses that the incorporation of MABF4 into the (5-AVA)0.034MA0.966PbI3 perovskite helps to reduce the charge recombination in the mixed perovskite cells, thus improving the open circuit voltage of the device. Furthermore, the new mixed perovskite was demonstrated to produce high-quality perovskite crystals and enhance the conductivity of the mixed perovskite.