Highly efficient and stable Eu3+-doped two-dimensional perovskites

Abstract

Compared to the three-dimensional (3D) counterparts, single-layered two-dimensional (2D) perovskites show high stability, high exciton binding energy and structural flexibility that are beneficial for light-emitting diodes (LEDs) applications. Yet, the emission peaks of single-layered 2D perovskites are strongly limited to the blue-green region due to their very strong quantum confined effect, hampering their application. Doping ions has been recognized as a promising way to tune emission wavelengths. In this work, we have prepared Eu3+ doped PEA2PbCl4 perovskites by a hot-injection method. Its Eu3+ emission is not stable, which disappears after exposed in the air due to the coordination of Eu3+ with H2O or O2. By exploiting strong ligands of thenoyltrifluoroacetone (TTA), the H2O or O2 can be replaced, resulting in a rigid coordination environment for Eu3+. Besides, energy level alignment can be modified by the passivation of TTA, leading to effective energy transfer from exciton to Eu3+. In the end, stable red-emitting perovskite is acquired with a photoluminescence quantum yield (PLQY) up to 83%. This work provides new synthetic strategies for the design of high-performance perovskite/lanthanide composites.