Reducing Defects of All-Inorganic ?-CsPbI2Br Thin Films by Ethylammonium Bromide Additives for Efficient Perovskite Solar Cells

Obtaining good-quality perovskite thin films is a fundamental facet that contributes to efficient inorganic perovskite solar cells. Herein, we successfully deposited ethylammonium skite films under ambient conditions. Detailed morphological, structural, optical, charge transport, photovoltaic performance, and stability properties have been studied. It is observed that the EABr additive helps to retard the crystal growth of perovskite films to produce a highly crystalline perovskite film with microsized grains (>1 mu m) and with reduced grain boundaries. The fabricated devices based on an optimum amount of EABr (4 mg mL-1) exhibited the highest 14.47 % power conversion efficiency. Moreover, the EABr-4 mg mL-1-assisted gamma-CsPbI2Br-based devices achieved a high thermal long-term stability and maintained similar to 75% of their initial efficiency over 180 h at 85 degrees C thermal stress under ambient conditions (relative humidity: similar to 35%) without encapsulation. This additive-assisted method suggests a new pathway to achieve high-quality perovskite films with a stabilized photoactive black phase and efficient devices.

Automated summary

This study successfully deposited ethylammonium perovskite thin films under ambient conditions and found that ethylammonium bromide additive helps to obtain highly crystalline and large-grain perovskite films. Devices fabricated with an optimized amount of ethylammonium bromide exhibited the highest power conversion efficiency and demonstrated good long-term stability under thermal stress.