Bingbing Zheng,Shuaigang Ge,Lingli Chen,Yijia Wen,Kaihuang Huang,Bingsuo Zou
Cd-based perovskite materials have the advantages of high emission efficiency and tunable emission, as well as broad application prospects in the field of optoelectronics. However, achieving multimode dynamic luminescence under UV light excitation in a single system is a great challenge. Here, we successfully prepared Sb3+/Pb2+co-doped Cs7Cd3Br13crystals by a simple hydrothermal method. Tunable emission from orange to white and then to blue, covering the wavelength range between 370 and 800 nm, was achieved by varying the doping concentration of Pb2+ions in Cs7Cd3Br13:0.5%Sb3+. Temperature-dependent photoluminescence (PL) spectra and density functional theory (DFT) calculations confirm that the wide-band white-light emission of Cs7Cd3Br13: Sb3+/Pb2+crystal comes from the first self-trapped exciton (STE1) of undoped Cs7Cd3Br13intrinsic capture state and the emission of free excitons (FEs) and STE2 induced by the confining effect and the Jahn–Teller effect by Pb2+incorporation, as well as the Sb triplet self-trapped exciton (STE3). More specifically, the samples with the best co-doped ratio exhibit significant excitation-wavelength-dependent luminescence characteristics and can realize the conversion of the emission color from white and blue to orange. Based on the tunable emission characteristics of three emission colors, the material has good prospects in encryption and anti-counterfeiting applications. This work provides a new strategy for the application of Cd-based halides in the field of anti-counterfeiting.
Meng Gao,Yuexiao Pan,Chengdong Peng,Yihong Ding,Hongzhou Lian,Liyi Li,Jun Lin
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 Mn2+ and Pb2+ co-doped Cs7Cd3Br13 crystals. The quantified bonding and nonbonding characters calculated by the crystal orbital Hamilton population analysis demonstrate that the Mn2+ and Pb2+ occupy preferentially in the [CdBr4]2– tetrahedrons rather than the [CdBr6]4– octahedrons in Cs7Cd3Br13. According to the PL spectral characteristic and the theoretical results, the broadband white light emission from Cs7Cd3Br13:Pb2+,Mn2+ crystals is ascribed to the multiple PL origins, i.e., the first self-trapped exciton (STE1) from the intrinsic trapping states of host lattice Cs7Cd3Br13, the d–d transition of Mn2+, and the second self-trapped exciton (STE2) induced by the introduction of Pb2+, respectively. The results calculated by density functional theory reveal that the incorporation of Mn2+ and Pb2+ has significantly improved the thermodynamic stability of the Cs7Cd3Br13 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.
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