李耀文副教授与李永舫院士合作在 Adv. Energy Mater. 上发表研究论文

New Strategy for Two-Step Sequential Deposition: Incorporation of Hydrophilic Fullerene in Second Precursor for High-Performance p-i-n Planar Perovskite Solar Cells

Guiying Xu^a, Rongming Xue^a, Weijie Chen^a, Jingwen Zhang^a, Moyao Zhang^a, Haiyang Chen^a,Chaohua Cui^a, Hongkun Li^a, Yaowen Li^*a（李耀文）, and Yongfang Li^*ab（李永舫）

^a State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials，Laboratory of Advanced Optoelectronic Materials，College of Chemistry Chemical Engineering and Materials Science，Soochow University，Suzhou 215123, China

^b CAS Research/Education Center for Excellence in Molecular Sciences，Institute of Chemistry Chinese Academy of Sciences，Beijing 100190, China

Adv. Energy Mater. 2018, 1703054

In p‐i‐n planar perovskite solar cells (pero‐SCs) based on methylammonium lead iodide (MAPbI₃) perovskite, high‐quality MAPbI₃film, perfect interfacial band alignment and efficient charge extracting ability are critical for high photovoltaic performance. In this work, a hydrophilic fullerene derivative [6,6]‐phenyl‐C₆₁‐butyric acid‐(3,4,5‐tris(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)phenyl)methanol ester (PCBB‐OEG) is introduced as additive in the methylammonium iodide precursor solution in the preparation of MAPbI₃perovskite film by two‐step sequential deposition method, and obtained a top‐down gradient distribution with an ultrathin top layer of PCBB‐OEG. Meanwhile, a high‐quality perovskite film with high crystallinity, less trap‐states, and dense‐grained uniform morphology can well grow on both hydrophilic (poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonic acid)) and hydrophobic (polytriarylamine, PTAA) hole transport layers. When the PCBB‐OEG‐containing perovskite film (pero‐0.1) is prepared in a p‐i‐n planar pero‐SC with the configuration of ITO/PTAA/pero‐0.1/[6,6]‐phenyl‐C₆₁‐butyric acid methyl ester/Al, the device delivers a promising power conversion efficiency (PCE) of 20.2% without hysteresis, which is one of the few PCE over 20% for the p‐i‐n planar pero‐SCs. Importantly, the pero‐0.1‐based device shows an excellent stability that can retain 98.4% of its initial PCE after being exposed for 300 h under ambient atmosphere with a high humidity, and the flexible pero‐SCs based on pero‐0.1 also demonstrate a promising PCE of 18.1%.