钙钛矿晶体的电荷复合动力学研究

本文利用紫外吸收光谱和稳态荧光光谱技术结合理论模型，研究了钙钛矿材料CH₃NH₃PbI₃晶体在光激发过程中的电荷复合动力学行为，进而获得晶体的扩散长度. 电荷载体的扩散长度是判断光电材料的重要参数. 研究通过合成两种不同缺陷态浓度的CH₃NH₃PbI₃晶体，测量这两种晶体在0.019∽4.268 μJ/cm²的激光激发下的时间分辨荧光光谱，利用动力学模型对光谱进行拟合，可以获得每个晶体的掺杂浓度，空穴浓度以及电荷复合参数. 将这些参数结合已有公式，最终可获得每个晶体的电荷载体的扩散长度.

Carrier Recombination of Organic-Inorganic 3D Halide Perovskite Single Crystals

Organic-inorganic 3D halide perovskite materials recently have become one of the major players of hybrid semiconductors for photovoltaic and optoelectronic applications. The diffusion length of charge carriers is one of the critical parameters for justifying photovoltaic applications of materials. In this work, we propose a realistic kinetic model in order to fully understand carrier relaxation rate of photoexcited organic perovskites with a negligible exciton formation in photoluminescence lifetime measurements. We find that the extraction of carrier relaxation rate has to be made from multiple fluence-dependent photoluminescence lifetime measurements with global fittings, instead of a traditional single fluence lifetime measurement. To demonstrate the validity of the model, two kinds of p-doped CH₃NH₃PbI₃ single crystals were grown up by intentionally increasing defects. Global fittings of the kinetic model to the two kinds of single crystals yield doping density, trap density, and recombination constants. Our methodology provides a self-contained approach to determine diffusion lengths of organic 3D halide perovskite materials.