Thermal Field Management for Stress Releasing Toward Efficient, Scalable Perovskite Photovoltaics

Perovskite solar cells are considered a promising photovoltaic technology, however, thermal expansion mismatch in conventional solution-controlled bottom-up thermal annealing results in strain in the perovskite layer, which significantly impairs the photovoltaic performance and scale-up manufacturing. Herein, a uniform thermal field is proposed to release the stress of perovskite film by offering a gas-solid (GS) reaction and simultaneously annealing process. Through slowly evaporation and diffusion of formamidine iodide salts into lead iodide-film, the pure α-phase black FAPbI₃-perovskite is formed, allowing for precise control of perovskite growth and residual strain relaxation. The oriented crystallization and reduced defects of perovskite films is also obtained by this thermal management, and thereby improves power conversion efficiency (PCE) of 23.58%, compared to the control device (22.77%), and with prolonged operational stability. Furthermore, the effectiveness of this approach is demonstrated by colorful tunability and large-area perovskite solar modules (PSMs) with an area of 859.1 cm², reaching an enhanced PCE from 12.74% to 16.56%. This approach highlights the importance of thermal field regulation for stress-released perovskite films for their scalability.