Fluorinated Low‐Dimensional Ruddlesden–Popper Perovskite Solar Cells with over 17% Power Conversion Efficiency and Improved Stability. Issue 37 (5th August 2019)

• Record Type: Journal Article
• Authors: Shi, Jishan; Gao, Yerun; Gao, Xiang; Zhang, Yun; Zhang, Junjie; Jing, Xin; Shao, Ming
• Is Part Of: Advanced materials. Volume 31:Issue 37(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-08-05
• Subjects: fluorination -- Ruddlesden–Popper perovskites -- solar cells; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201901673
• Languages: English
• ISSNs: 0935-9648

Abstract

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 a spacer to fabricate quasi‐2D (4FPEA)2 (MA)4 Pb5 I16 ( n = 5) perovskite solar cells. The champion device exhibits a remarkable PCE of 17.3% with a J sc of 19.00 mA cm −2, a V oc of 1.16 V, and a fill factor (FF) of 79%, which are among the best results for low‐dimensional RPP solar cells ( n ≤ 5). The enhanced device performance can be attributed as follows: first, the strong dipole field induced by the 4‐fluoro‐phenethylammonium (4FPEA) organic spacer facilitates charge dissociation. Second, fluorinated RPP crystals preferentially grow along the vertical direction, and form a phase distribution with the increasing n number from bottom to the top surface, resulting in efficient charge transport. Third, 4FPEA‐based RPP films exhibit higher film crystallinity, enlarged grain size, and reduced trap‐state density. Lastly, the unsealed fluorinated RPP devices demonstrate superior humidity and thermal stability. Therefore, the fluorination of the long‐chain organic cations provides a feasible approach for simultaneously improving the efficiency and stability of low‐dimensional RPP solar cells. Abstract : A remarkable high efficiency of 17.34% is achieved for low‐dimensional Ruddlesden–Popper perovskite (RPP) solar cells ( n ≤ 5) by using a fluorinated phenylethalammonium (4‐fluoro‐phenethylammonium (4FPEA)) organic cation. These fluorinated devices also show the better humidity and thermal stability as compared to nonfluorinated phenylethlammonium (PEA) devices. These findings provide a feasible approach for simultaneously improving the efficiency and stability of low‐dimensional RPP solar cells.