有机卤化铅钙钛矿的表面钝化及对钙钛矿太阳电池性能的影响

Perovskite solar cells (PSCs) are the latest development and one of the research focuses of thin film solar cells, and their record power conversion efficiency has reached 22.1%. It has been proved that appropriate amount of PbI2 existing in CH3NH3PbI3 (MAPbI3) films could improve the power conversion efficiency of PSCs, however, the corresponding mechanism is not yet completely clear, and the amount and location of PbI2 couldn’t be precisely controlled..Herein, we introduce pulsed laser deposition technique into the preparation of MAPbI3 films by two-step solution method to achieve the precise control of the parameters of PbI2 passivation layer in MAPbI3 films. The influence of PbI2 passivation layer on carrier extraction, transport, and recombination will be investigated through ultrafast spectroscopy, transient photovoltage/photocurrent, ultraviolet photoelectron spectroscopy, and electrochemical impedance spectroscopy measurements combined with first-principle calculations, and then the mechanism of PbI2 passivation effect will be improved and perfected. Furthermore, the influence of PbI2 passivation effect on the performance of PSCs will also be studied for improving the performance of PSCs. This study will provide technical and scientific basis for improving the performance of PSCs by utilizing PbI2 passivation effect.

钙钛矿太阳电池（PSCs）是薄膜太阳电池的最新发展和研究热点之一，其光电转换效率已达22.1%。CH3NH3PbI3（MAPbI3）薄膜中适量PbI2的存在已被证明可以提高PSCs的光电转换效率，但是其作用机理尚未完全明晰，PbI2存在的量和位置亦无法做到精确控制。.本项目在两步溶液法制备MAPbI3薄膜的过程中引入脉冲激光沉积技术（PLD）实现MAPbI3薄膜中PbI2钝化层位置和厚度等参数的精确控制；利用超快光谱、光电压/光电流瞬态响应、紫外光电子能谱、交流阻抗谱等测试手段结合第一性原理计算，研究PbI2钝化层对MAPbI3薄膜和PSCs中载流子的提取、传输和复合行为的影响规律，完善PbI2钝化作用的机制和机理；并研究PbI2钝化作用对PSCs性能的影响规律，以提高PSCs的性能。本项目的研究将为利用PbI2钝化作用提高PSCs性能提供技术基础和科学依据。

有机卤化铅钙钛矿太阳电池（PSCs）是新型薄膜太阳电池近年的研究热点之一，其性能迅速发展，目前的光电转换效率记录已达25.5%，制备成本也相对较低低，是最有希望实用化的薄膜太阳电池之一。CH3NH3PbI3（MAPbI3）光吸收层中在适当位置存在的适量PbI2已被证明可起到钝化缺陷提升PSCs性能的效果，但相应的作用机理尚未完全明确，PbI2存在的量和位置也无法精确控制。.本项目引入脉冲激光沉积技术（PLD）对MAPbI3薄膜中过量PbI2的位置和量的进行调控，研究了脉冲激光沉积参数（激光能量、脉冲数、本底真空等）对MAPbI3薄膜的质量、PbI2含量以及MAPbI3基PSCs性能的影响规律，并通过瞬态荧光寿命、电化学阻抗谱、瞬态光电压谱等研究了相应的机理。.研究中，通过PLD技术和一步旋涂法实现了I类PbI2钝化层对MAPbI3薄膜的有效钝化并优化了钝化参数，研究了作用机理。I类PbI2的钝化显著提升了器件的载流子寿命，最优PSCs的其光电转换效率为16.68%。通过准分子激光辐照诱导实现了II类PbI2钝化层对MAPbI3薄膜的有效钝化。MAPbI3薄膜的荧光寿命和PSCs器件的瞬态光电压及载流子寿命均获得明显提升，最优器件实现了19.38%的光电转换效率。此外，还将PbI2的钝化作用应用于基于铜铁矿CuCrO2空穴传输层和三阳离子混合钙钛矿[(FAPbI3)0.87(MAPbBr3)0.13]0.92[CsPbI3]0.08的反式结构PSCs中，获得了相对较高开路电压。.本项目的研究进一步揭示了PbI2对有机卤化铅钙钛矿薄膜和器件钝化作用的机制和机理，可在一定程度上为利用PbI2钝化作用提高PSCs及其它光电器件的性能提供科学依据。