Effects of anti-solvent temperature on microstructures and photovoltaic properties of TiO2@MAPbI3 core-shell nanowire arrays

Core-shell nanowire array is a kind of composite structure that combines the characteristics of nuclear and shell materials, but it commonly suffers from poor shell quality, insufficient coverage and severe device recombination defects. The anti-solvent method is an auxiliary strategy that can provide supersaturation driving force for perovskite crystals. Its temperature plays a decisive role in the solvent volatilization of perovskite precursor and the formation of solute supersaturation environment. Toluene, with low polarity, low boiling point and low cost, is the preferred anti-solvent for preparing of small-area batteriy in laboratory. In this work, TiO2@MAPbI3 core -shell nanowire arrays were constructed by hydrothermal and spin-coating methods, and then the microstructure of core-shell structures and photovoltaic properties of perovskite solar cells were improved by varying the temperature of the anti-solvent toluene. When the preheating temperature of toluene was 75 degrees C, the device photovoltaic performance of PCE reached 7.42%. The shell layer quality was significantly improved and the carrier recombination rate was significantly reduced after the anti-solvent modification, suggesting that the microstructure and photovoltaic performance of the core-shell structure could be optimized by the anti-solvent temperature. This would provide some guidance for improving the photovoltaic performance of perovskite solar cells.