Yang Yang,Zisheng Wang,Jiahao Jie,Chunqing Hou,Yilong Song,Yuhao Fu,Lijun Zhang,Qingfeng Dong
Lead-based perovskites have been prominently featured across diverse fields. Nevertheless, the intrinsic toxicity associated with lead compounds presents substantial environmental and health concerns. Thus, it has become imperative to seek alternatives devoid of lead. Our research presents a pioneering solution to this predicament by zeroing in on cesium-manganese-bromide-based perovskite crystals. Our research involves doping the pseudohalide anion acetate (Ac−) into halide positions within CsMnBr3·2H2O crystals, resulting in a remarkable improvement in their luminescence characteristics. The optimized CsMnBr3·2H2O:Ac− crystals displayed a photoluminescence quantum yield (PLQY) surpassing 70%, marking a substantial advancement compared to the modest PLQY observed in pristine CsMnBr3·2H2O bulk crystals. Theoretical analysis was employed to ascertain the precise lattice position occupied by Ac−. High-performance ion chromatography confirmed the presence of Ac− and determined the pseudohalide concentration. Studies on carrier dynamics to investigate the impact of Ac− on CsMnBr3·2H2O revealed that the significant enhancement in emission following Ac− doping is linked to the mitigation of nonradiative carrier trapping processes. The differences in Mn–Mn dipole–dipole and spin-exchange interactions were verified through electron paramagnetic resonance, magnetic measurements and femtosecond transient photoluminescent spectroscopy. The experimental data prove that the doping of Ac− leads to a decrease in spin-exchange interaction, which consequently decelerates the separation of holes and electrons, subsequently facilitating the recombination process. Our study provide valuable insights into the mechanism by which pseudohalide affects the perovskite sample, with Ac− suppressing non-radiative recombination processes and also influencing the exciton dissociation, leading to enhanced efficiency in radiative recombination processes. The findings furnish a promising method of conditioning the properties of perovskite crystals, which offers a new way for materials design towards diverse emerging applications.
Yao Ju,Junfeng Qu,Yuru Duan,Yuge Feng,Cai Liang,Xiaoxi Zhou,Shuhong Xu,Chunlei Wang
The dynamic time-gating anticounterfeiting based on phosphorescence materials is the current hot topic of research. However, the short change time from nanosecond-level fluorescence false information to μs-level fluorescence correct information makes it easily deciphered just by turning off ultraviolet (UV) light. Herein, we first reported a new type of minute-level dynamic time-gating anticounterfeiting technology based on the ethanol-induced phase transition between the red-emitting CsMnBr3 crystals and green-emitting Cs3MnBr5 crystals. Our results show that the dissolution of MnBr2·2H2O from CsMnBr3 into ethanol triggers the phase transition. Moreover, the time of phase transition can be adjusted by mixing with different (3-aminopropyl)triethoxysilane (APTES) concentrations. By using CsMnBr3 and APTES-CsMnBr3 with different phase-transition times, the true information on “SEO” can be designed to show only in the conditions of specific stimulus (ethanol) and specific time range. Otherwise, the false information on “SEU” or “888” is shown. In comparison to previously reported dynamic time-gating anticounterfeiting technology based on phosphorescence materials, the current reported minute-level dynamic time-gating anticounterfeiting technology based on phase transition increased the difficulty of decryption. Moreover, the combination of nontoxic fluorescence materials and daily life available stimulus (ethanol) makes the current anticounterfeiting technology have great practical value.
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