This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record . Please cite this article as doi: 10.1002/solr.202000060 This article is protected by copyright. All rights reserved Tailoring Perovskite Adjacent Interfaces by Conjugated Polyelectrolyte for Stable and Efficient Solar Cells Bowei Li, Yuren Xiang, K. D. G. Imalka Jayawardena, Deying Luo, John F. Watts, Steven Hinder, Hui Li, Victoria Ferguson, Haitian Luo, Rui Zhu, S. Ravi P. Silva*, Wei Zhang* B. Li, Dr. Y. Xiang, Dr. I. Jayawardena, Dr. H. Li, V. Ferguson, Prof. S. R. P. Silva, Dr. W. Zhang Advanced Technology Institute, Department of Electrical and Electronic Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK E-mail: wz0003@surrey.ac.uk; s.silva@surrey.ac.uk Dr. S. Hinder, Prof. J. F. Watts, The Surface Analysis Laboratory, Department of Mechanical Engineering Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK Dr. D. Luo, Prof. R. Zhu State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics & Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China H. Luo, Dr. H. Li Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China Accepted Article