Simultaneous Long-Persistent Blue Luminescence and High Quantum Yield within 2D Organic-Metal Halide Perovskite Micro/Nanosheets.

Molecular solid-state materials with long-lived luminescence (such as thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) systems) are promising for display, sensoring, and bio-imaging applications. However, the design of such materials that exhibit both long luminescent lifetime and high solid-state emissive efficiency remains an open challenge. Two-dimensional (2D) organic-metal halide perovskite materials have a high blue-emitting quantum yield of up to 63.55 % and ultralong TADF lifetime of 103.12 ms at ambient temperature and atmosphere. Our design leverages the combined influences of a 2D space/electronic confinement effect and a modest heavy-atom tuning strategy. Photophysical studies and calculations reveal that the enhanced quantum yield is due to the rigid laminate structure of perovskites, which can effectively inhibit the non-radiative decay of excitons.