基于硅量子点/富勒烯基分子新型杂化电子传输层的倒置平面钙钛矿太阳电池研究

Inverted planer perovskite solar cell has simple fabrication process at low temperature, hence, is possible for large-area, low-cost and flexible solar cell production. Therefore, it is one of the most promising perovskite solar cells for industrialization. However, relatively low electron mobility of fullerene-based molecules commonly employed as the electron transporting material in such solar cell has prohibited the further promotion of device performance. Therefore, in this project we plan to design and fabricate novel silicon quantum dot/fullerene-based molecule hybrid electron transporting materials. In which, silicon quantum dots can effectively absorb the low energy photons penetrating through perovskite active layer, and photogenerated electrons will inject into fullerene-based molecules with the assistance of the built-in-potential established between silicon quantum dot and fullerene-based molecule because of the energy level mismatch. This can substantially enhance the electron concentration and conductivity of novel hybrid electron transporting layer. In the following, we will try to figure out the dominating reasons or limitation factors for J-V hysteresis and device efficiency by systematically studying the working mechanisms of solar cells. Finally, we plan to realize the high performance inverted planer perovskite solar cells with less J-V hysteresis by carefully improving material quality, device structure and fabrication process. This work could provide solid theoretical and technical foundations facing to the development of perovskite solar cells. Furthermore, it will promote the extensive study and vast applications of silicon quantum dots, and provide valuable knowledge to related research fields.

倒置平面钙钛矿太阳电池可实现低温制备且工艺简单，从而使大面积、廉价、柔性高性能电池的制备成为可能，是极具产业化潜力的钙钛矿太阳电池之一。然而由于当前常用富勒烯基电子传输材料迁移率较低，限制了电池性能的大幅提升。本项目将构建硅量子点/富勒烯基分子新型杂化电子传输材料。通过硅量子点实现对透过钙钛矿活性层的低能光子的有效吸收，并借助其与富勒烯基分子间的能级失配，将硅量子点中的光生电子注入富勒烯基分子，从而大幅提高新型杂化电子传输层的电子浓度及电导率；在此基础上系统研究电池机理，揭示J-V曲线迟滞现象的发生机制、制约电池效率的关键因素；通过进一步改善材料质量、改进电池结构及创新优化制备工艺，最终实现无明显J-V曲线迟滞现象的高性能倒置平面钙钛矿太阳电池；进而为钙钛矿太阳电池的发展提供坚实的理论和技术支持。另外，本研究也将推动对硅量子点的深入研究与广泛应用、并为相关领域的研究提供有价值的参考。

本项目以实现无明显J-V曲线迟滞现象的高性能平面钙钛矿太阳电池为目标。为此在以下几方面开展了系统深入的研究：1）高质量钙钛矿薄膜的制备及性能调控。通过MACl及DMF协同作用获得了形貌均匀的纯α相钙钛矿薄膜；进一步在钙钛矿A位引入适量GA离子实现了钙钛矿体缺陷的有效钝化；2）载流子传输层及传输层结构优化。通过元素掺杂大幅提升了传输层的载流子迁移率；通过合理设计多层载流子传输结构避免了传输层制备工艺对钙钛矿活性层的影响，同时有效抑制了功能薄膜之间的元素互扩与反应；3）体表界面修饰。在埋底界面及表界面引入功能分子，如，二甲双胍、KCl、PDMAI及TMPMAI等有效钝化了钙钛矿上下表界面处的缺陷，并促进了高质量钙钛矿薄膜的生长；4）器件光管理。在器件入光面构建不同直径的二维六角密排SiO2纳米颗粒阵列，显著增强了器件在300~800 nm宽波长范围内的光捕获。从而促进了载流子的高效分离、传输及收集；抑制了载流子的非辐射复合；抑制了器件表面的光反射损失，促进了器件对太阳光的有效利用。最终优化太阳电池实现了23.11%的最高效率及22.76%的稳态输出效率，并且器件表现出较好的环境稳定性。另外，还尝试了超声喷涂制备钙钛矿薄膜设备及工艺的产业化成果转化。该项目的成功实施为钙钛矿太阳电池的发展提供了坚实的理论和技术支持。