Xia Yijie, Du Shuaishuai, Huang Pengju, Wu Luchao, Yan Siyu, Wang Weizhi, Zhong Gaoyu
School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Department of Materials Science, Fudan University, Shanghai 200433, China.
Nanomaterials (Basel). 2021 Dec 6;11(12):3310. doi: 10.3390/nano11123310.
The temperature-dependent photoluminescence (PL) properties of an anti-perovskite [MnBr]BrCs sample in the temperature range of 78-500 K are studied in the present work. This material exhibits unique performance which is different from a typical perovskite. Experiments showed that from room temperature to 78 K, the luminous intensity increased as the temperature decreased. From room temperature to 500 K, the photoluminescence intensity gradually decreased with increasing temperature. Experiments with varying temperatures repeatedly showed that the emission wavelength was very stable. Based on the above-mentioned phenomenon of the changing photoluminescence under different temperatures, the mechanism is deduced from the temperature-dependent characteristics of excitons, and the experimental results are explained on the basis of the types of excitons with different energy levels and different recombination rates involved in the steady-state PL process. The results show that in the measured temperature range of 78-500 K, the steady-state PL of [MnBr]BrCs had three excitons with different energy levels and recombination rates participating. The involved excitons with the highest energy level not only had a high radiative recombination rate, but a high non-radiative recombination rate as well. The excitons at the second-highest energy level had a similar radiative recombination rate to the lowest energy level excitons and a had high non-radiative recombination rate. These excitons made the photoluminescence gradually decrease with increasing temperature. This may be the reason for this material's high photoluminescence efficiency and low electroluminescence efficiency.
本工作研究了反钙钛矿[MnBr]BrCs样品在78 - 500 K温度范围内的温度依赖光致发光（PL）特性。这种材料表现出与典型钙钛矿不同的独特性能。实验表明，从室温到78 K，发光强度随温度降低而增加。从室温到500 K，光致发光强度随温度升高而逐渐降低。不同温度下的实验反复表明，发射波长非常稳定。基于上述不同温度下光致发光变化的现象，从激子的温度依赖特性推导其机制，并在稳态PL过程中涉及的不同能级和不同复合率的激子类型的基础上解释实验结果。结果表明，在78 - 500 K的测量温度范围内，[MnBr]BrCs的稳态PL有三种不同能级和复合率的激子参与。涉及的最高能级激子不仅具有高辐射复合率，而且具有高非辐射复合率。第二高能级的激子具有与最低能级激子相似的辐射复合率和高非辐射复合率。这些激子使得光致发光随温度升高而逐渐降低。这可能是这种材料高光致发光效率和低电致发光效率的原因。
