Department of Mechanical Engineering and Centre of Nanofibers and Nanotechnology (NUSCNN), National University of Singapore 117576, Singapore.
Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR) , No. 08-03, 2 Fusionopolis Way, Innovis 138634, Singapore.
ACS Appl Mater Interfaces. 2017 Jan 25;9(3):2358-2368. doi: 10.1021/acsami.6b12845. Epub 2017 Jan 13.
PbI-enriched mixed perovskite film [FAMAPb(IBr)] has been widely studied due to its great potential in perovskite solar cell (PSC) applications. Herein, a FAMAPb(IBr) film has been fabricated with the temperature-dependent optical absorption spectra utilized to determine its exciton binding energy. A ∼13 meV exciton binding energy is estimated, and a near-unity fraction of free carriers out of the total photoexcitons has been obtained in the solar cell operating regime at equilibrium state. PSCs are fabricated with this mixed perovskite film, but a significant electron transport barrier at the TiO-perovskite interface limited their performance. CsCO and CsI are then utilized as functional enhancers with which to substantially balance the electron and hole transport and increase the carriers (both electrons and holes) mobilities in PSCs, resulting in much-improved solar-cell performance. The modified PSCs exhibit reproducible power conversion efficiency (PCE) values with little hysteresis effect in the J-V curves, achieving PCEs up to 19.5% for the CsCO-modified PSC and 20.6% when subsequently further doped with CsI.
富含 PbI 的混合钙钛矿薄膜 [FAMAPb(IBr)] 由于在钙钛矿太阳能电池 (PSC) 应用中有很大的潜力而被广泛研究。在此，我们利用温度依赖的光吸收谱来制备 FAMAPb(IBr) 薄膜，以确定其激子束缚能。在平衡状态的太阳能电池工作模式下，我们估计激子束缚能约为 13meV，并且获得了总光生激子中近 1 的自由载流子分数。我们使用这种混合钙钛矿薄膜来制备 PSCs，但在 TiO2-钙钛矿界面存在显著的电子传输势垒，限制了它们的性能。然后，我们使用 CsCO 和 CsI 作为功能增强剂，以大大平衡电子和空穴的传输，并提高 PSCs 中的载流子（电子和空穴）迁移率，从而显著提高太阳能电池的性能。经过修饰的 PSCs 在 J-V 曲线中表现出可重复的功率转换效率（PCE）值，几乎没有滞后效应，其中 CsCO 修饰的 PSC 的 PCE 高达 19.5%，而进一步掺杂 CsI 后则可达到 20.6%。
