Long-Term Stabilization of Two-Dimensional Perovskites by Encapsulation with Hexagonal Boron Nitride

Metal halide perovskites are known to suffer from rapid degradation, limiting their direct applicability. Here, the degradation of phenethylammonium lead iodide (PEA2PbI4) two-dimensional perovskites under ambient conditions is studied using fluorescence, absorbance and fluorescence lifetime measurements. It is demonstrated that a long-term stability of two-dimensional perovskites can be achieved through the encapsulation with hexagonal boron nitride. While un-encapsulated perovskite flakes degrade within hours, the encapsulated perovskites are stable for at least three months. In addition, encapsulation considerably improves the stability under laser irradiation. The environmental stability, combined with the improved durability under illumination, is a critical ingredient for thorough spectroscopic studies of the intrinsic opto-electronic properties of this material platform.