Ghosh Supriya, Pradhan Bapi, Zhang Yiyue, Hofkens Johan, Karki Khadga J, Materny Arnulf
Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759, Bremen, Germany.
Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
Phys Chem Chem Phys. 2021 Feb 19;23(6):3983-3992. doi: 10.1039/d0cp05538g.
Quasi two-dimensional perovskites have attracted great attention for applications in light-emitting devices and photovoltaics due to their robustness and tunable highly efficient photoluminescence (PL). However, the mechanism of intrinsic PL in these materials is still not fully understood. In this work, we have analysed the nature of the different emissive states and the impact of temperature on the emissions in quasi two-dimensional methyl ammonium lead bromide perovskite (q-MPB) and cesium lead bromide perovskite (q-CPB). We have used spatially resolved phase-modulated two-photon photoluminescence (2PPL) and temperature-dependent 2PPL to characterize the emissions. Our results show that at room temperature, the PL from q-MPB is due to the recombination of excitons and free carriers while the PL from q-CPB is due to the recombination of excitons only. Temperature-dependent measurements show that in both materials the linewidth broadening is due to the interactions between the excitons and optical phonons at high temperatures. Comparing the characteristics of the emissions in the two systems, we conclude that q-CPB is better suited for light emitting devices. With a further optimization to reduce the impact on the environment, q-CPB-based LEDs could perform as well as OLEDs.
准二维钙钛矿因其稳定性和可调谐的高效光致发光（PL），在发光器件和光伏领域的应用中备受关注。然而，这些材料中本征PL的机制仍未完全理解。在这项工作中，我们分析了准二维甲基铵溴化铅钙钛矿（q-MPB）和溴化铯铅钙钛矿（q-CPB）中不同发射态的性质以及温度对发射的影响。我们使用空间分辨相位调制双光子光致发光（2PPL）和温度相关的2PPL来表征发射。我们的结果表明，在室温下，q-MPB的PL源于激子与自由载流子的复合，而q-CPB的PL仅源于激子的复合。温度相关测量表明，在两种材料中，线宽展宽是由于高温下激子与光学声子之间的相互作用。比较两个系统中发射的特性，我们得出结论，q-CPB更适合用于发光器件。通过进一步优化以减少对环境的影响，基于q-CPB的发光二极管（LED）可以与有机发光二极管（OLED）表现得一样好。
