Enhanced Photovoltaic Performance of Mesoscopic Perovskite Solar Cells by Controlling the Interaction between CH3NH3PbI3 Films and CsPbX3 Perovskite Nanoparticles

We report the incorporation of all-inorganic highly stable CsPbX3 (X = I, Br) based perovskite nano particles (NPs) on top of a bulk CH(3)NH(3)Pbl(3)perovskite thin film. This design utilizes the photogeneration ability of perovskite NPs and also improves the interfacial charge transport which happens to be a critical factor in deciding the photovoltaic performance of any solar cell device. With variation in the lead halide (PbX2 X = I, Br, Cl) content, the synthesized CsPbX3 NPs shows tunable band-edge position and fluorescence characteristics. The interaction of all inorganic NPs with the bulk perovskite resulted in improved hole injection and electron blocking characteristics leading to enhanced light harvesting efficiency. The CsPbBr3 and CsPbI3 perovskite NPs were used for fabricating the bulk-NP structure due to their better absorption and valence band edge characteristics. The inclusion of CsPbI3 NPs on top of the bulk perovskite showed a significant increment in the power conversion efficiency of 28%, in comparison with a reference sample without NPs, due to significant improvements in current density, open circuit voltage, and fill factor.