Cerium Ion Promoting the Emission of Self-Trapped Excitons of Quasi-2D Europium Halide Perovskites for Self-Activated White Light-Emitting
Xinyu Fu, Yao Li, Huwei Li, Jing Feng, Hongjie Zhang
Abstract
Lead-free halide perovskites (LFHPs) have been intensively studied due to their characteristics of nontoxicity, unique structure, and tunable photoluminescence properties by replacing lead ions. Here, we report a special quasi-two-dimensional (quasi-2D) RbEu 2 Cl 5 through a self-reducing hot-injection method. The as-prepared RbEu 2 Cl 5 shows two sharp blue emissions (430 and 470 nm) and a shoulder broad emission (510 nm), which could be attributed to the 4f 6 5d 1 → 4f 7 electronic dipole transition of Eu 2+ in different coordination structures (CN = 8 and 7) and self-trapped excitons (STEs), respectively. Then, Ce 3+ ions are introduced into RbEu 2 Cl 5 to enhance the STEs luminescence by crystal lattice distortion and heighten photoluminescence quantum yields. At the optimal doping concentration of 10%, RbEu 2 Cl 5:Ce 3+ NCs could exhibit excellent self-activated warm white emission. Furthermore, the corresponding white light-emitting diodes device with the CIE color coordinate (0.36, 0.38) was fabricated by combining RbEu 2 Cl 5:10% Ce 3+ NCs with an ultraviolet light-emitting diodes chip. This work not only develops a new LFHPs structure, but also provides potential LFHPs for self-activated white light-emitting applications.