White Light Emission from Single-Component Cs<sub>7</sub>Cd<sub>3</sub>Br<sub>13</sub>:Pb<sup>2+</sup>,Mn<sup>2+</sup> Crystals with High Quantum Efficiency and Enhanced Thermodynamic Stability
Meng Gao, Yuexiao Pan, Chengdong Peng, Yi‐hong Ding, Hongzhou Lian, Liyi Li, Jun Lin
Abstract
Single-component white light emitters are particularly attractive for fabricating economical solid-state devices for display and lighting. Herein, an efficient white light with photoluminescence quantum yields approaching 98% has been obtained in Mn 2+ and Pb 2+ co-doped Cs 7 Cd 3 Br 13 crystals. The quantified bonding and nonbonding characters calculated by the crystal orbital Hamilton population analysis demonstrate that the Mn 2+ and Pb 2+ occupy preferentially in the [CdBr 4 ] 2– tetrahedrons rather than the [CdBr 6 ] 4– octahedrons in Cs 7 Cd 3 Br 13 . According to the PL spectral characteristic and the theoretical results, the broadband white light emission from Cs 7 Cd 3 Br 13:Pb 2+,Mn 2+ crystals is ascribed to the multiple PL origins, i.e., the first self-trapped exciton (STE1) from the intrinsic trapping states of host lattice Cs 7 Cd 3 Br 13, the d–d transition of Mn 2+, and the second self-trapped exciton (STE2) induced by the introduction of Pb 2+, respectively. The results calculated by density functional theory reveal that the incorporation of Mn 2+ and Pb 2+ has significantly improved the thermodynamic stability of the Cs 7 Cd 3 Br 13 structure with lower defect formation energies, which is verified by the experimental observation in the temperature-dependent PL spectra of the emitting crystals. The findings here provide a new perspective for a single-component white light via creating multiple PL centers in a single matrix as well as help in the elucidation of the preferential site occupancy mechanism of the dopants in different symmetrical units.