功能性有机配体调控无机钙钛矿纳米晶稳定性与电荷传输性能

Cesium lead halide (CsPbX3, X=Cl, Br and I) perovskite nanocrystals have been exhibiting promising potentials in optical and photonic applications; whereas there remain challenges in improving stability of nanocrystals against surroundings while enhancing charge carrier transfer (CT) efficiency. This project proposes a means by engineering functional ligand-pairs to improve the stability and CT efficiency of nanocrystals simultaneously. Acid-base ligand pairs are indispensable in synthesis of nanocrystals. Specifically, in our proposal we will introduce conjugated acid ligands as the CT channels, together with siloxane base ligands forming ultrathin wrappings around particles, to realize synthesis of stable nanocrystals with high CT efficiencies. Ultrathin wrappings can be realized via a control of hydrolysis processes, and are expected to function with no interference upon conjugated ligands. Additionally, this functional acid-base pair provides ways controlling morphology, size distributions and optical properties of nanocrystals. Based on the stable and CT-efficient nanocrystals, we will systematically investigate charge carrier dynamics in perovskite nanostructures especially with a focus on interfacial CT processes. Our project is expected to pave ways in applications of perovskite nanostructures in photonic and detector fields.

目前在无机钙钛矿纳米晶光电应用领域中，提升纳米晶的稳定性和加强电荷传输速率仍然互相制约。本项目提出引入功能性配体对--酸基有机共轭配体作为电荷通道、碱基硅氧烷配体形成性质稳定的超薄包覆层--从而平衡和解决稳定性和电荷传输速率两者的矛盾；同时，引入的功能性配体本身可以作为酸碱配体对，调控纳米晶的合成，保持纳米晶良好的尺寸、形貌和光学性质。具体说来，本项目从纳米晶合成理论中的酸碱对作用机制出发，引入功能性的有机配体，提升无机钙钛矿CsPbX3 (X = Cl, Br and I)纳米晶稳定性以及电荷传输性能；进一步系统探究合成条件对纳米晶尺寸、形貌以及光学性质的调控；利用时间分辨光谱技术，结合Marcus电荷传输理论，探究无机钙钛矿纳米晶中电荷传输行为，验证并总结加强电荷传输的方式。本项目的实施对钙钛矿CsPbX3纳米晶在光电材料和器件领域中的进一步应用提供了新的思路。

本项目结合项目研究计划和实际情况，针对配体调控的稳定性和电荷传输速率两个方面，开展了大量的研究，并取得卓有成效的进展。截止结题，本项目优化并实现了基于硅氧烷包覆的高稳定性CsPbX3纳米晶合成工艺，并且利用后处理配体交换方法，实现了对CsPbX3纳米晶配体体系的调控；进一步基于合成方面的成果，结合时间分辨光谱技术和第一性原理计算，深入探讨了不同配体体系对CsPbX3纳米晶界面电荷传输过程的影响机制，包括交联硅氧烷、直链油酸油胺、芳香环萘甲酸配体等，成功总结了配体结构和电学性质对CsPbX3纳米晶电荷传输的调控规律；与此同时，基于稳定性好、电荷传输性能优异的CsPbX3纳米晶，本项目开发和实现了具备高亮度、高电光转换量子效率优点的LED光电器件，进一步夯实了CsPbX3纳米晶在高性能光电器件方面的应用基础；此外，在实现项目既定的研究内容和基础上，围绕CsPbX3纳米晶进行了热载流子动力学机理研究方面的拓展，积极探索CsPbX3纳米晶在未来高性能光电应用中的可行性。