Efficient Perovskite Solar Cells with Enhanced Thermal Stability by Sulfide Treatment.

The performance degradation of perovskite solar cells (PSCs) under harsh environment (e.g., heat, moisture, light) is one of the greatest challenges for their commercialization. Herein, a conjugated sulfide 2-mercaptobenzimidazole (2MBI) is applied to significantly improve the photovoltaic properties and thermal stability of PSCs. When treated with heat, 2MBI cross-links with each other on the perovskite surface to facilitate charge transportation, suppress the escape of volatile species, and guide the rearrangement of surface perovskite grains. PSCs with 2MBI modification reach a PCE as high as 21.7% and maintain high-efficiency output during and after thermodestruction at 85 °C, while the unmodified ones suffer severe degradation. Unencapsulated devices after thermodestruction achieve over 98% of initial efficiency after 40-day storage under ambient conditions.