基于TiO2复合电子传输层的柔性自驱动钙钛矿光探测器的构筑及光电性能研究

This project intends to employ flexible ultra-thin titanium plate (or titanium wire) as both substrate and contact electrode, and develop effective approaches to prepare uniform and thickness-adjustable Type-II TiO2 homojunction and TiO2-SnO2 heterojunction thin films as electron transport layers for the construction of flexible self-powered perovskite photodetectors. The approaches of regulating the oxygen vacancies and doping of anions and cations in TiO2 and SnO2 films are systematically investigated to obtain composite films with tunable conductivity, electron mobility and band structure. The relationship among the synthesis conditions, physical parameters, band structure of the films and optoelectronic properties of detector is investigated to determine the best experimental parameters. The charge transport kinetics at the interface between the composite electron transport layer and perovskite layer is studied to reveal the influence of the built-in electric field at the junction interface on the carrier separation and transport efficiencies. Flexible self-powered perovskite photodetector with high responsivity and specific detectivity will be prepared by optimizing the interface and fabrication process. The project will bring new ideas and possibilities for the research on perovskite photodetectors, which will lay theoretical and experimental foundation for the practical application of photodetectors in the future.

本项目拟采用柔性超薄钛片（或钛线）作为基底和接触电极，开发有效方法在其表面制备均匀和厚度可调的II型TiO2同质结和TiO2-SnO2异质结薄膜作为电子传输层，从而构筑柔性自驱动钙钛矿光电探测器。系统探索TiO2和SnO2薄膜中氧空位和阴阳离子掺杂调控的方法，获得电导率、电子迁移率和能带结构等参数可调的复合薄膜。研究复合薄膜合成条件、物性参数、能带结构以及探测器的光电性能参数之间的关系，确定最佳实验参数。研究复合电子传输层与钙钛矿界面处电荷传输动力学过程，阐明结界面内建电场对于载流子的分离和传输效率的影响规律。通过优化界面与工艺，制备出具有高响应度和比探测率的柔性自驱动钙钛矿光探测器。本项目对于钙钛矿光探测器的研究带来了新的思路和可能，将为未来光探测器的实际应用奠定理论和实验基础。

本项目采用有序结构设计和添加剂工程等手段，系统的研究了基于钙钛矿薄膜的光电探测器的调控工艺，阐明了钙钛矿薄膜的形貌、组分、能带与光电性能之间关系，开发了柔性、高比探测率、宽带/窄带双工作模式等一系列钙钛矿光电探测器。具体成果包括：提出利用微球辅助模板法结合反溶剂法，制备了嵌套式反蛋白石结构钙钛矿三维有序异质结，解决了平板状钙钛矿异质结缺陷态密度高、界面电荷复合严重和环境稳定性差等问题；通过精确调控前驱体溶剂中二甲基亚砜添加剂的含量并结合热铸工艺控制结晶过程和步骤，调控了二维钙钛矿中的晶体取向性和相分布，实现了沿垂直方向相组分的梯度有序生长，导致形成了薄膜内部梯度能级结构，从而实现了有效的电荷产生和超快的相间电荷转移；筛选出合适的添加剂，利用乙酰胺中的羰基和氨基与钙钛矿成分成键调节了钙钛矿结晶转相过程，并钝化了表界面缺陷，抑制载流子非辐射复合，使得器件表现出优异弱光探测能力和线性动态响应。本项目的实施对深入理解钙钛矿薄膜的形貌、组分、能带与光电性能之间关系具有重要价值，将为钙钛矿光电探测器的应用与发展提供必要技术支撑与保障。研究结果已发表基金第一标注SCI论文24篇，授权国家发明专利2项，培养硕士研究生7名，参加国内外学术会议10余人次。