有机体异质结在拓宽钙钛矿太阳能电池近红外光谱响应中的应用

Typical hybrid perovskites, such as MAPbI3 or FAPbI3, show the light-harvesting range mainly to the visible-light region (300−840 nm), which results in large solar radiation losses in the near-infrared (NIR) region and thus impedes the further improvement of perovskite solar cell (PSC) efficiency. One effective strategy to further improve the performance of PSC is to broaden the light absorption to the NIR spectral region by integrating PSCs with another low-bandgap organic bulk heterojunction (BHJ) layer, as the low-bandgap BHJ layer can provide additional light harvesting in the NIR region, which dramatically minimizes spectral losses. However, up to now, there is a lack of systematic experimental investigations and theoretical principles on how to select suitable low-bandgap BHJ materials which are compatible with the perovskite, such as the energy level, carrier mobility and material solubility. Besides, further investigation is also needed to understand the influence of perovskite/BHJ interface on the integrated device performance. Therefore, this project would start from the experimental selection of BHJ donor and acceptor materials, combined with the first principle calculations to model the donor and acceptor building blocks, thus guiding the material selection from the molecular level. Moreover, this project would grope for strategies to control the photoelectric properties of organic BHJ. The influence of perovskite/BHJ interface energy level alignment and charge carrier transport balance would also be studied. This project would push forward the study of PSC spectral manipulation, and contribute to the development of highly efficient perovskite photovoltaic devices exceeding the single-junction Shockley−Queisser efficiency limits.

钙钛矿（例如MAPbI3，FAPbI3）一般吸收300-840 nm范围的可见光，近红外区域的光谱未得到有效利用，成为制约钙钛矿太阳能电池效率提升的重要因素。有机体异质结(BHJ)能通过与钙钛矿的集成，拓展器件近红外光谱响应，是进一步提高电池效率的可行方法。然而，目前对于如何选择与钙钛矿能级、迁移率、溶解性等性质相匹配的窄带隙BHJ材料缺乏系统的实验数据和理论论证，钙钛矿/BHJ界面及其对器件性能的影响亦缺乏深入研究。针对此，本项目准备从BHJ给体和受体材料的实验优选入手，辅以第一性原理计算构建给体和受体材料结构单元模型，从分子层面指导材料选择，重点摸索BHJ光电性质的调控策略，并进一步研究钙钛矿/BHJ界面能级排列和载流子输运平衡对集成器件近红外光谱响应的影响。本项目将推动钙钛矿器件光谱调控的研究，有助于发展突破Shockley−Queisser极限的高效率钙钛矿太阳能电池。

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