Fluorinated Low‐Dimensional Ruddlesden–Popper Perovskite Solar Cells with over 17% Power Conversion Efficiency and Improved Stability

• DOI: 10.1002/adma.201901673
• Publication Date: 2019-08-05T07:59:04Z
• Authors: Jishan Shi; Yerun Gao; Xiang Gao; Yun Zhang; Junjie Zhang; Xin Jing; Ming Shao
• Keywords: Perovskite solar cell

Abstract Low‐dimensional Ruddlesden–Popper perovskites (RPPs) exhibit excellent stability in comparison with 3D perovskites; however, the relatively low power conversion efficiency (PCE) limits their future application. In this work, a new fluorine‐substituted phenylethlammonium (PEA) cation is developed as spacer to fabricate quasi‐2D (4FPEA) 2 (MA) 4 Pb 5 I 16 ( n = 5) perovskite solar cells. The champion device exhibits remarkable PCE of 17.3% J sc 19.00 mA cm −2 , V oc 1.16 V, and fill factor (FF) 79%, which are among best results for low‐dimensional RPP cells ≤ 5). enhanced performance can be attributed follows: first, strong dipole field induced by 4‐fluoro‐phenethylammonium organic facilitates charge dissociation. Second, fluorinated crystals preferentially grow along vertical direction, form phase distribution increasing number from bottom top surface, resulting efficient transport. Third, 4FPEA‐based films higher film crystallinity, enlarged grain size, reduced trap‐state density. Lastly, unsealed devices demonstrate superior humidity thermal stability. Therefore, fluorination long‐chain cations provides feasible approach simultaneously improving