Nature Photonics ( IF 31.241 ) Pub Date : 2020-01-13 , DOI: 10.1038/s41566-019-0572-6 Hui Ren; Shidong Yu; Lingfeng Chao; Yingdong Xia; Yuanhui Sun; Shouwei Zuo; Fan Li; Tingting Niu; Yingguo Yang; Huanxin Ju; Bixin Li; Haiyan Du; Xingyu Gao; Jing Zhang; Jianpu Wang; Lijun Zhang; Yonghua Chen; Wei Huang
Two-dimensional Ruddlesden–Popper phase (2DRP) perovskites are known to exhibit improved photostability and environmental stability compared with their three-dimensional (3D) counterparts. However, fundamental questions remain over the interaction between the bulky alkylammoniums and the 2DRP perovskite framework. Here, we unambiguously demonstrate that a sulfur–sulfur interaction is present for a new bulky alkylammonium, 2-(methylthio)ethylamine hydrochloride (MTEACl). In addition to a weaker van der Waals interaction, the interaction between sulfur atoms in two MTEA molecules enables a (MTEA)2(MA)4Pb5I16 (n = 5) perovskite framework with enhanced charge transport and stabilization. The result is 2DRP perovskite solar cells with significantly improved efficiency and stability. Cells with a power conversion efficiency as high as 18.06% (17.8% certified) are achieved, along with moisture tolerance for up to 1,512 h (under 70% humidity conditions), thermal stability for 375 h (at 85 °C) and stability under continuous light stress (85% of the initial efficiency retained over 1,000 h of operation at the maximum power point).