Stabilization of Black FAPbI 3 Perovskite by Interaction with the Surface of the Polymorphic Phase α‐PbO

Abstract The black phase of formamidinium lead iodide, FAPbI 3 , is optically active and promising for optoelectronics applications. However, it is difficult to synthesize and stabilize at room temperature since it thermodynamically tends toward the photoinactive yellow phase. Based on density functional theory computations, the potential of PbO semiconductor substrates to stabilize the black phase of FAPbI 3 perovskite is investigated and shown that, interestingly, it can be effectively stabilized over the yellow phase at room temperature when deposited on the polymorphic phase α‐PbO.