Exploring stability of formamidinium lead trihalide for solar cell application

Formamidinium lead triiodide (FAPbI3) is a promising photoactive perovskite for low-cost and efficient solar cells. This article reports on an experimental investigation on the stability of FAPbI3 by comparison with that of widely-used methylamidinium lead triiodide (MAPbI3). A hydration of the FAPbI3 with moisture could be the dominant mechanism for its degradation in air, rather than a common thermal decomposition in the MAPbI3. This can be mainly contributed to a relatively strong bond formation between formamidinium ions (FA+) and I−. Consequently, the stability of FAPbI3 based devices can be greatly enhanced by removal moisture in the surrounding. This conclusion renders FAPbI3 extremely attractive for stable perovskite solar cells with fine encapsulation.