Improved photostability of metal halide perovskites by microstructure modulation for photovoltaic application

Despite the excellent optoelectronic properties of metal halide perovskites in a photovoltaic device, they suffer from serious and poor photostability in real-scenario operating conditions during test and storage. As common, perovskite undergoes complex variation under successive light radiation, the most conspicuous effect is the photo-induced ion migration and phase segregation, which happens the quickest, dramatically influences build-in field, and hence remarkable poor photostability of photovoltaic devices. Herein, we adopted thiourea as an intermediate regulator to slow down the nucleation process of perovskite and form larger grain sizes, thus, fewer grain boundaries, namely fewer migration channels, decrease the ion migration possibility under illuminance and strengthen the photostability of perovskite films. Experiment results showed that such a strategy improves device reproducibility and photostability under continuous scanning and prolongs device lifetime stored at air condition.