含羧酸类极性基团的有机电荷传输材料及其钙钛矿太阳能电池性能研究

Perovskite solar cells(PSCs) have attracted great interests during last few years. For the commercial application of PSCs, one of the most important scientific issues lies in fabricating devices with not only high efficiency but also desirable stability. To realize this object, it is necessary to develop high performance charge transport materials in addition to the study of novel and stable perovskite materials. A good charge transport layer could decrease the trap concentration and charge aggregation, improve the interfacial properties of the different function layer and subsequently result in an efficient device with good stability. Titanium oxide and Spiro-MeOTAD are typically used as the efficient charge transport, but the drawback is that they need high temperature or doping treatment. It undoubtedly will bring high energy consumption, poor reproducibility and even lead to the decomposition of active perovskite, the stability is seriously affected. Recently, we developed a hole-transport polythiophene and an electron-transport fullerene derivative containing carboxyl groups which could be processed by solution method at room temperature. In comparison with the corresponding neutral materials, the efficiencies of the PSCs are significantly increased and could reach 18-19% after introducing carboxyl group. These doping free PSCs also show very promising stability, the efficiency still remain 95% of its initial value after 100 days, but the efficiency and stability still need improvement in further and the mechanism study is also urgent. Based these findings, we will focus on novel transport materials with different polar group like carboxyl in this project. We aim to understand the mechanism behind by investigating the relationship between chemical structures, film properties and device characteristics. We believe that our work will not only provide new insight into designing highly efficient charge transport materials but also provide new ideas into optimizing device stability.

钙钛矿太阳能电池是国际上的研究热点，目前制约其发展的关键问题在于：如何在兼顾高效率的同时，实现良好的稳定性。除了新型钙钛矿材料的研发，另一个必要条件是发展性能优异的电荷传输材料，改善界面性质，减少缺陷和电荷积累，协同提高器件效率和稳定性。二氧化钛或Spiro-MeOTAD等常用材料，需要高温或掺杂处理，能耗高、重现性差、甚至会导致钙钛矿分解，稳定性也有待提高。最近，我们采用可低温溶液成膜的聚噻吩或富勒烯羧酸衍生物，作为空穴或电子传输层，效率可达18-19%，性能优于不含羧酸基团的中性材料，器件无需掺杂且表现出良好的稳定性，但效率和稳定性如何进一步提高及机理还急需深入研究。本项目目标旨在此基础上，针对含羧酸类极性基团的有机材料体系，进一步探索材料化学结构、薄膜性质与器件性能参数之间的变化规律，澄清效率和稳定性的各自影响因素。为新材料的开发提供理论指导，为实现效率与稳定兼备的器件提供新的思路。

钙钛矿太阳能电池是国际上的研究热点，目前制约其发展的关键问题在于：如何在兼顾高效率的同时，实现良好的稳定性。除了新型钙钛矿材料的研发，另一个必要条件是发展性能优异的电荷传输材料，改善界面性质，减少缺陷和电荷积累，协同提高器件效率和稳定性。在本工作中，首先研究了含羧酸的聚噻吩空穴传输材料（P3CT）和含羧酸的富勒烯电子传输材料（CPTA、CPTE）在钙钛矿太阳能器件中的电荷传输和缺陷钝化作用，通过分子结构调节实现了在正型和反型结构中均实现了20%以上的器件效率，系统研究了含羧酸在界面传输中的作用机理；此外还采用含羧酸且可原位交联的小分子材料（TMTA、E2CA）作为钙钛矿晶界的钝化材料，实现超过200小时的工作稳定性，研究了晶界对器件稳定性之间的内在联系；最后还开发了可同时实现晶界钝化和修复作用的含羧酸的有机盐（PbPyA2、MAPyA）,实现了效率高于16%且稳定的纯无机钙钛矿太阳能电池的制备。