Stimulating Efficient and Stable Ultralong Phosphorescence of 2D Perovskites by Dual-Mode Triplet Exciton Stabilization

Ultralong room-temperature phosphorescence (URTP) has attracted widespread attention in modern optoelectronics, but it is mainly observed in organic materials through deliberate molecular design. Here, we report efficient URTP emission from two-dimensional (2D) perovskites by stabilizing the triplet excitons of organic cations energetically in a type I hybrid quantum-well-like structure and structurally in a 2D layered gallery. Such a dual-mode cooperative stabilization strategy is realized facilely by the methoxyl group modification of π-conjugated phenethylammonium cation, which has little influence on the 2D perovskite architecture. Moreover, a strong URTP (∼490 nm) with a remarkably long lifetime of up to 480 ms and quantum yield of 7.86% are achieved, along with excellent environmental robustness against moisture and oxygen invasion and good thermal stability in a wide range of temperatures. Furthermore, both multiple information encryption and afterglow white lighting devices are realized, greatly expanding the development of hybrid perovskite phosphors for advanced 2D URTP materials and applications.