Superior stabilized α-FAPbI3 perovskite solar cells with efficiency exceeding 24 %

Abstract

-Fabrication of a stabilized black phase of formamidinium triiodide perovskite film is a critical issue to warrant efficient perovskite solar cells with considerable intrinsic and external stability. To address this obstacle, the study focuses on assembling α-FAPbI₃ perovskite solar cells. To realize a stabilized α-FAPbI₃, a δ-FAPbI₃ film was annealed at 150 $°C$ at ambient air with a humidity level of 25 % to convert α-FAPbI₃. Then, this $\delta \to \alpha$ FAPbI₃ was crushed, and some of it was added to a fresh FAPbI₃ perovskite precursor to fabricate desirable α-FAPbI₃ layers. The cost-effective method, along with the stabilization of α-FAPbI₃, showed a high ability to promote charge transfer and suppress trap transitions in the perovskite layer. The engineered perovskite solar cells recorded a considerable filling factor of 82.89 % with a champion efficiency of 24.16 %, higher than the recorded efficiency of 21.25 %. In addition, the robust stability enables the FAPbI₃ solar cells to work steadily for more than 1200 h under simulated sunlight irradiance with just an 8 % loss in their performance.