Exploring Stability of Formamidinium Lead Trihalide for Solar Cell Application

Formamidinium lead triiodide (FAPbI) is a promising photoactive perovskite for low-cost and efficient solar cells. This article reports on an experimental investigation on the stability of FAPbI by comparison with that of widely-used methylamidinium lead triiodide (MAPbI). A hydration of the FAPbI with moisture could be the dominant mechanism for its degradation in air, rather than a common thermal decomposition in the MAPbI. This can be mainly contributed to a relatively strong bond formation between formamidinium ions (FA) and I. Consequently, the stability of FAPbI based devices can be greatly enhanced by removal moisture in the surrounding. This conclusion renders FAPbI extremely attractive for stable perovskite solar cells with fine encapsulation.