溶液路线构筑混合钙钛矿薄膜太阳电池及其性能研究

The recently developed perovskite (ABX3) thin film solar cell with the component of organic (A) metal (B) halide (X) possess the simple preparation technology, low cost, higher performance and long-term stability property, which open up a new way in green renewable energy research. However, due to the short research time of this kind of device, the understand of the key scientific problems about the composition, structure, the optical and electrical performances of this perovskite multi-function layer materials is still a challenge. In this project, the band position, crystal and microstructure of mixed perovskite can be adjusted by the regulation of chemical constitutes of B or X unit to enhance spectral response matching with the sun lights and enhancing charge transfer performance to build high performance perovskite thin-film solar cells. The n-type semiconductor blocking layer, mesoporous support thin films, mixed perovskite (light absorption and charge transfer), and p-type semiconductor hole transporting layer by layer assembled through the solution-processable route. And the thin-film solar cell device prototype with wide spectral response could be expected to obtain breakthrough of the power conversion efficiency.Investigation of the influence of band position of mixed perovskite, light absorption and charge transport properties which changed by adjusting B or X units are mainly focuses on. Understanding of the dynamics mechanism of charge separation and recomposition in interface, charge transport and collection, and the every part of multi-layer electrode contribute to the device power conversion efficiency are researched,which can lay the foundation for the rational design of high performance solar cells and components optimization.

最近研发的有机（A）金属（B）卤化（X）物钙钛矿（ABX3）薄膜太阳能电池具有工艺简单、低价、高效和稳定的特点，在寻找绿色可再生能源领域开辟了崭新的途径。但是，该类器件研究时间短，对钙钛矿多功能层的组成、结构和光学、电学性能方面的关键科学问题认识不足。本项目提出通过B或X单元化学组成的改变来调整混合钙钛矿的能带、晶体和微观结构，使其光谱响应与太阳光匹配、电荷传输性能改善，进而构筑高性能钙钛矿薄膜太阳能电池。采用溶液路线逐层组装n-型半导体阻挡层、介孔支架薄膜层、混合钙钛矿（光吸收和电荷传输）层、以及p-型半导体空穴传输层，研制宽光谱响应的薄膜太阳电池器件原型，获得功率转化效率突破。着重研究B或X单元组成的调控对混合钙钛矿的能带结构、光吸收和电荷传输性能的影响规律，理解激子解离和复合、载流子输运和收集、多层薄膜每个部位对器件功率转化率的贡献，为高性能太阳电池的理性设计和器件优化奠定基础。

本项目，采用溶液加工路线逐层组装构筑有机（A）金属（B）卤化物（ABX3）钙钛矿太阳能电池（PSC），系统开展了TiO2阻挡层（BL-TiO2）的优化、选取阴或阳离子掺杂改性钙钛矿活性层和器件结构优化等方面的研究工作。结果表明，BL-TiO2形貌、厚度及其性能直接影响PSC性能，具有一定厚度高质量BL-TiO2不仅有效的阻挡空穴，还有利于电子传输和提取，进而增强PSC性能。以FTO/BL-TiO2/MP-TiO2/钙钛矿/Spiro-OMeTAD/Ag（或Au）为器件结构， MAPbI3为钙钛矿基质材料，掺杂阴离子（Br-或Cl-）或阳离子（FA+或Cs+）调控其组成；采用一步或两步法制备了高质量的混合钙钛矿薄膜，并详细研究了溶液浓度、溶剂种类和溶剂比率、晶化温度和时间等因素对薄膜的影响，优化确定了钙钛矿活性层制备的最佳条件。以(FA)0.3(MA)0.7PbI3为钙钛矿活性层、Spiro-OMeTAD为空穴传输层和Au为对电极，在手套箱中制备的PSC功率转换效率达到了16.13%，但器件稳定性较低。在此基础上，探索研究了提高PSC的稳定性、优化器件结构和选用疏水性碳电极保护等关键技术。在自然空气条件下采用液相法制备了基于碳电极、无空穴传输层的PSC。验证了基于碳电极的PSC具有较好的稳定性和应用前景。本项目获得的成果不仅为薄膜太阳电池的性能改善和器件结构优化提供新的思路，同时也为高性能太阳能电池的研制和应用奠定了基础。