题目：Improving the stability and performance of perovskite solar cells via off-the-shelf post-device ligand treatment
作 者：Hong Zhang a, Xingang Ren a, Xiwen Chen b, Jian Mao a, Jiaqi Cheng a, Yong Zhao a, Yuhang Liu c, Jovana Milic c, Wan-Jian Yin b, Michael Gr?tzel c and Wallace C. H. Choy *a
aDepartment of Electrical and Electronic Engineering, The University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR, China.
bSoochow Institute for Energy and Materials Innovations (SIEMIS), College of Physics, Optoelectronics and Energy & Collaborative Innovation Centre of Suzhou Nano Science and Technology, Soochow University, 215006, Suzhou, China
cLaboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
摘要：While metal halide perovskite solar cells (PVSCs) have drawn intense attention due to their high solar-to-power conversion efficiency (PCE), their practical application is hampered by their poor long-term stability against moisture. Although strategies have been reported to solve this issue, these methods are introduced during core-device fabrication processes which will increase the risk of introducing unexpected impurities during the fabrication. Herein, we introduce the first kind of simple post-device ligand (PDL) treatment to significantly improve the PCE of completely fabricated PVSCs from 18.7% to 20.13%. Meanwhile, the stability of the treated devices without any encapsulation remarkably improves, with 70% PCE maintained under ambient conditions after a 500-hour maximum-power-point tracking test, while the control unencapsulated device will completely break down within 100 hours. Equally important is that this post-device treatment shows a special ‘stitching effect’, namely repairing the as-fabricated ‘poor devices’ by healing the defects of the perovskite active region, and can improve the PCE by over 900%. We also experimentally and theoretically study the fundamental mechanism of the improvement. Consequently, our approach greatly improves the production yield of high-quality PVSCs and their module performances as well as the reduction of lead-waste. Additionally, the treatment is an off-the-shelf post-device approach that can be integrated into any existing perovskite-device fabrication, offering a general strategy to improve the stability and performance of perovskite optoelectronic devices.