Department of Electrical and Computer Engineering, University of Toronto, 35 St. George Street, Toronto, ON, M5S 1A4, Canada.
State Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory, School of Physics, Peking University, 100871, Beijing, China.
Nat Commun. 2018 Apr 23;9(1):1607. doi: 10.1038/s41467-018-04029-7.
Formamidinium-lead-iodide (FAPbI)-based perovskites with bandgap below 1.55 eV are of interest for photovoltaics in view of their close-to-ideal bandgap. Record-performance FAPbI-based solar cells have relied on fabrication via the sequential-deposition method; however, these devices exhibit unstable output under illumination due to the difficulty of incorporating cesium cations (stabilizer) in sequentially deposited films. Here we devise a perovskite seeding method that efficiently incorporates cesium and beneficially modulates perovskite crystallization. First, perovskite seed crystals are embedded in the PbI film. The perovskite seeds serve as cesium sources and act as nuclei to facilitate crystallization during the formation of perovskite. Perovskite films with perovskite seeding growth exhibit a lowered trap density, and the resulting planar solar cells achieve stabilized efficiency of 21.5% with a high open-circuit voltage of 1.13 V and a fill factor that exceeds 80%. The Cs-containing FAPbI-based devices show a striking improvement in operational stability and retain 60% of their initial efficiency after 140 h operation under one sun illumination.
基于碘化甲脒-铅（FAPbI）的钙钛矿材料具有低于 1.55eV 的带隙，这对于光伏应用具有吸引力，因为它们的带隙接近理想值。为了实现基于 FAPbI 的太阳能电池的高性能，人们依赖于通过顺序沉积法来制造这些器件；然而，由于在顺序沉积的薄膜中掺入铯阳离子（稳定剂）存在困难，这些器件在光照下的输出不稳定。在这里，我们设计了一种钙钛矿成核方法，该方法能够有效地掺入铯，并有益地调节钙钛矿的结晶。首先，将钙钛矿晶种嵌入 PbI 薄膜中。钙钛矿晶种作为铯源，并作为核来促进钙钛矿形成过程中的结晶。具有钙钛矿成核生长的钙钛矿薄膜表现出较低的陷阱密度，所得的平面太阳能电池实现了稳定的 21.5%的效率，开路电压超过 1.13V，填充因子超过 80%。含 Cs 的 FAPbI 基器件在运行稳定性方面有显著提高，在 1 个太阳光照下运行 140 小时后，仍保留初始效率的 60%。
