基于无序度调控构建的新型铋/锑基窄带隙光吸收材料及其光电性能探索

Perovskites are attractive materials for photovoltaic application with power conversion efficiencies over 22%. The two issues restrict their further development are the poor stability and the toxicity from lead. A lead-free strategy is demonstrated in this project through the replacement of lead with the environment-friendly bismuth and antimony. The narrow band gap Bi and Sb based A2BB'X6 perovskites with wide absorption, high charge carriers mobility, and open structures are constructed by disordering the original configuration through the inductive effect from the A site, the doping effect in the B(B') site, and the heating effect. Together with the theoretically analysis, we will analyze the inherent relationship between the configuration and the photovoltaic performance, control the synergy of photon, phonon and electron, and realize the rational structure design. Finally, the preparation of high quality thin films based on the new materials and their application in the photovoltaics will be studied. This investigation will provide extensive understanding on the development of stable and efficient lead-free perovskites. The applicant has published a series of papers on perovskites in the last five years in the journals, such as Nat. Commun.、Adv. Mater., contributing to the successful implementation of this project.

光电转换效率已突破22%的钙钛矿太阳能电池受限于含铅材料毒性高、环境稳定性差等问题的制约。本项目拟探索化学稳定的新型铋/锑基钙钛矿材料，提出钙钛矿结构中无序度调控的新思路，设计构建窄带隙、高效光子利用的铋/锑基光吸收材料体系，探索集成高稳定型、高效率的新型原型器件。1）利用A位诱导效应、B(B')位掺杂效应和热效应进行结构无序度调控，发展具备高吸光度、高电荷迁移率、结构空旷的窄带隙铋/锑基A2BB'X6 (B'=Bi, Sb)无毒稳定钙钛矿光伏材料体系；2）揭示无序度调控对晶体结构和光电性能的内在影响，深刻认识微观层面上光子、声子、电子间的协同作用机制；3）开展高性能材料的薄膜化和器件化研究，实现器件性能的突破。申请人近5年在Nat. Commun.、Adv. Mater.等杂志发表了一系列钙钛矿材料和器件相关论文，扎实的工作基础有望顺利实施和完成所资助项目。

受限于传统铅基钙钛矿在毒性、环境稳定性等方面的制约，本项目聚焦新型铋、锑基无铅钙钛矿新材料探索，基于结构无序度调控策略，系统开展了窄带隙、宽光谱吸收无铅钙钛矿的设计制备与性能表征，揭示了结构与光电性能间的内在关联，实现了材料在光电转换器件中的应用。取得的重要结果如下：（1）利用压力驱动、热驱动、元素掺杂三种调控手段实现了Cs2AgBiBr6双钙钛矿晶体结构与能带重构，Cs2AgBiBr6带隙由2.10 eV左右分别降低至1.32 eV，1.69 eV，和1.51 eV，光子响应范围由 < 600 nm 拓展至整个可见光和近红外区域，揭示了结构与光电性能的内在关联。（2）利用合成工艺调控，实现了高质量Cs2AgBiBr6大单晶、薄膜与纳米晶的可控制备，光电器件性能显著提升，其中基于窄带隙Cs2AgBiBr6太阳能电池效率与本征相比提高了93%。（3）设计合成了一系列新型铋、锑基无机化合物及有机-无机杂化分子晶体，展现出优异的光电磁特性。项目资助已发表SCI论文3篇，待发表5篇，申请发明专利2项。培养中国科学院青促会会员1名，博士研究生1名，硕士研究生3名。项目的实施对于窄带隙无铅钙钛矿新材料的开发具有一定的指导意义。