钙钛矿材料中动态无序的全光学调控及其超快动力学效应研究

As one of the most promising materials in the area of optoelectronics, perovskites have attracted intensive attentions owing to their amazing optoelectronic properties including high optical absorption coefficients, high mobility and long lifetime of photo-generated carriers. However, despite the excellent discoveries so far, the crystalline structural nature and the microscopic interacting mechanism behind the observed properties remain unclear, which certainly limits the further application development of perovskite materials. Based on the current status, our project plans to investigate the phenomenon of dynamic disorder which is essentially related to the soft lattice nature of perovskite structures, by the means of all-optical manipulation of dynamic disorders and time-resolved optical spectroscopies performed on our self-built double-pump time-resolved optical spectroscopic system. Our research will focus on studying the methods of selectively controlling different types of dynamic disorders by optical pulses, measuring the ultra-fast effects of dynamic disorders on the band structures and carrier dynamical processes in lead halide perovskites, and investigating the mechanisms of soft perovskite structure interacting with optoelectronic processes from a microscopic and dynamical point of view. The proposed research in the project will lead to new insight into the phenomenon of dynamic disorders in perovskites as well as its ultra-fast effects on transient optical processes and interacting mechanisms with carrier dynamics, which will promote our understanding of the effects of the microscopic lattice nature on the macroscopic optoelectronic performances and provide a solid research foundation for developing innovative materials and functional devices of perovskite structures.

作为光电领域热点研究之一，钙钛矿材料因其高光学吸收系数、光生载流子的高迁移率和长寿命等光电特性而备受关注，但其优异光电性能的内部微结构根源及微观光电物理机制尚不清晰，影响钙钛矿材料光电应用的进一步开拓。基于此现状，本项目从钙钛矿材料的组分和结构本质出发，以典型铅卤化物钙钛矿为研究对象，利用自主设计搭建的双泵浦时间分辨光谱测量系统，对钙钛矿型微结构密切相关的动态无序效应进行全光学调控，通过测量不同动态无序效应对载流子微观动力学行为的超快作用，深入研究钙钛矿材料独特晶格特性对电子能带结构、载流子超快行为的光电作用机制。主要实验将在我们最近设计和搭建的双泵浦时间分辨光谱测量系统上完成。预期本工作将有助于我们对新型光电材料中动态无序效应及其超快光学过程和光电作用机制产生新认知，显著提升我们对钙钛矿新型光电材料微结构及宏观光电物理特性的理解，为钙钛矿材料及功能器件的创新发展提供一个扎实的研究基础。

光生载流子与晶格环境及载流子环境的相互作用决定了半导体材料最基本的光电特性，而从载流子动力学行为出发探测载流子超快作用过程，能够获得载流子与其环境因素相互作用的更清晰物理图像。本项目以MaPbX3和CsPbX3卤化物为代表的钙钛矿材料作为主要研究对象，利用自主设计搭建的时间分辨光学克尔效应光谱(TROKE)、时间分辨光学克尔旋转光谱(TRKR)和时间分辨光致发光光谱(TRPL)测量功能，开展了综合性的光谱测量研究，尤其聚集于晶格动态无序效应对载流子行为的作用、载流子间互作用对载流子输运与复合过程的影响。本研究工作中发展了双泵浦时间分辨光谱技术和光学显微时间分辨光谱技术，与TRKR和TRPL光谱技术相结合，既实现了时间可控的多调制光学激发，又获得了微米量级空间分辨率的时间分辨光谱测量功能。所搭建的光谱测量系统覆盖了350-2400nm的光谱范围，具有飞秒量级和皮秒量级的时间分辨能力，满足近紫外至近红外波段半导体材料中载流子超快动力学过程的光谱检测需求。本项目基于钙钛矿材料超快动力学研究所发展的技术方法和理论模型，可以广泛应用于不同类型半导体材料、荧光材料中载流子行为研究，我们已经开展了实验方法与理论模型的拓展性研究，与多家研究机构的不同团队开展了深入的合作研究，研究对象包括了过渡金属硫属化合物二维半导体材料、Mn离子激活荧光材料、AlGaN量子阱结构、超级电容器功能材料等。在该项目基金的支持下，已在Journal of Luminescence、Nanoscale、ACS Photonics等期刊发表SCI论文16篇，培养了3名硕士研究生和一名博士研究生。