基于锡掺杂与表面钝化的α-CsPbI3量子点的高效率无机钙钛矿太阳能电池的研究

α-CsPbI3 quantum dots (QDs) based inorganic perovskite solar cells are crucial to the commercialization for their low-cost and stability. Unfortunately, the efficiency of the α-CsPbI3 QDs solar cells remains very low to date due to enlarged band gap and increased surface defects caused by the size effect and surface effect of QDs, respectively. In order to solve these problems, we intend to focus on the key factors of the band gap and the surface defects which affect the device efficiency directly. On the one hand, by doping tin element, the bandgap of the QDs could be adjusted continuously, that can match the absorption spectrum of QDs with the solar spectrum and that will improve the device efficiency. On the other hand, surface passivation with lead halide salts will reduce the trap density of QDs, tune their work function and balance the electron and hole transport rate which can realize effective separation of the photo exciton, enhance built-in electrical field and eliminate current-voltage hysteresis in solar cells, respectively. Finally, the efficiency of the α-CsPbI3 QDs solar cells will be greatly improved, and the mechanism of the influence of the band gap and the surface defect on the cell performance is revealed through the combination of theory and experiment. Based on above, we will provide technical and theoretical support for the further improvement of the efficiency of inorganic perovskite QDs solar cells.

基于α-CsPbI3量子点的无机钙钛矿太阳能电池成本低廉性能稳定，具有重要发展和应用前景。针对目前由于量子点尺寸效应引起的禁带宽度增大和表面效应引起的表面缺陷增加导致α-CsPbI3量子点太阳能电池效率较低的问题，本项目拟围绕影响电池效率的量子点禁带宽度与表面缺陷的因素，通过掺杂减小量子点禁带宽度的锡元素并调控其掺杂比例，实现其禁带宽度的连续可调性，使其能够很好的与太阳光谱进行匹配；通过铅卤盐调节量子点表面的元素分布钝化其表面，降低其表面缺陷密度、调节其功函数以及平衡其电子-空穴的迁移率，实现电池中光生载流子的有效分离、内建电场的增强以及电流-电压曲线迟滞现象的消除。最终大幅提升电池效率，并通过关联电池性能与量子点结构特征，期望从理论与实验结合上，揭示量子点禁带宽度与表面缺陷对电池性能的影响机制。以此为据，为无机钙钛矿量子点太阳能电池效率的进一步提高提供具有普适性指导意义的技术与理论支持。

基于CsPbX3量子点的无机钙钛矿太阳能电池的成本低廉及器件性能稳定高，具有重要发展和应用前景。针对目前由于量子点尺寸效应引起的禁带宽度增大和表面效应引起的表面缺陷增加导致CsPbX3量子点太阳能电池效率较低的问题，本项目围绕影响电池效率的量子点禁带宽度与表面缺陷的因素，通过引入离子掺杂 (B位及X位) 减小量子点禁带宽度并调控其掺杂比例，实现其禁带宽度的连续可调性，使其能够很好的与太阳光谱进行匹配，并阐述掺杂对CsPbX3物理特性及其器件性能的影响机制；在此基础上，通过铅卤盐调节量子点表面的元素分布钝化其表面，降低其表面缺陷密度、调节其功函数以及平衡其电子-空穴的迁移率，实现电池中光生载流子的有效分离、内建电场的增强以及电流-电压曲线迟滞现象的消除。最后，结合中间相的引入，获得亚稳态相CsPbX3，并具有比CsPbX3量子点结构更高的稳定性；后续，并通过合理的CsPbX3量子点结构、组分及光谱工程，获得了效率超过18%且无迟滞现象的CsPbX3太阳能电池。.在该项目的支撑下(资助号：61704099)，项目负责人在Nature Communications (1篇), Angewandte Chemie International Edition (1篇), Joule (1篇), Advanced Energy Materials (4篇), ACS Energy Letters (1篇), Advanced Science (4篇), Nano Energy (4篇) 等高水平期刊上以第一作者/共同通讯作者身份共发表学术论文32篇，其中，论文 (Adv. Energy Mater. 2018, 8 (15), 1703246.) 被评为2018年中国最具影响百篇国际学术论文及第十四届陕西省优秀学术论文。