Journal of Energy Chemistry 27 (2018) 650–672 http://www.journals.elsevier.com/ journal-of-energy-chemistry/ Contents lists available at ScienceDirect Journal of Energy Chemistry journal homepage: www.elsevier.com/locate/jechem Review Progress in hole-transporting materials for perovskite solar cells Xichuan Yang 1,∗ , Haoxin Wang 1 , Bin Cai, Ze Yu, Licheng Sun State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), Dalian 116024, Liaoning, China a r t i c l e i n f o Article history: Received 28 August 2017 Revised 25 December 2017 Accepted 25 December 2017 Available online 4 January 2018 Keywords: Perovskite solar cells Efficient charge extraction Hole transporting materials Recombination losses a b s t r a c t In recent years the photovoltaic community has witnessed the unprecedented development of perovskite solar cells (PSCs) as they have taken the lead in emergent photovoltaic technologies. The power conver- sion efficiency of this new class of solar cells has been increased to a point where they are beginning to compete with more established technologies. Although PSCs have evolved a variety of structures, the use of hole-transporting materials (HTMs) remains indispensable. Here, an overview of the various types of available HTMs is presented. This includes organic and inorganic HTMs and is presented alongside recent progress in associated aspects of PSCs, including device architectures and fabrication techniques to pro- duce high-quality perovskite films. The structure, electrochemistry, and physical properties of a variety of HTMs are discussed, highlighting considerations for those designing new HTMs. Finally, an outlook is presented to provide more concrete direction for the development and optimization of HTMs for high- efficiency PSCs. © 2018 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved. Xichuan Yang received his Ph.D. in 2002 from the Dalian University of Technology (DUT), China. Before that he worked as a project leader in enterprises and developed more than 20 fine chemical products from the labora- tory to mass production. Then he worked as a post- doc at Stockholm University (2003–2004). From 2004, he worked as an associate professor of the State Key Labora- tory of Fine Chemicals, DUT, China. His current research interest focuses on investigation on solar energy materi- als & devices including dye/quantum dot sensitized solar cells, perovskite solar cells and organic photovoltaics. Haoxin Wang received his B.S. from Shenyang Univer- sity of Chemical Technology in 2012. Currently, he is a Ph.D. candidate in the State Key Laboratory of Fine Chem- icals, Dalian University of Technology (DUT), China. His research interest focuses on investigation on solar energy materials and perovskite solar cells. ∗ Corresponding author. E-mail address: yangxc@dlut.edu.cn (X. Yang). 1 These authors contributed equally to this work. Bin Cai received his B.S. from Wuhan Institute of Tech- nology (2010–2014). Currently he is a Ph.D. student in State Key Laboratory of Fine Chemicals, Dalian University of Technology (DUT), China. His research mainly focuses on the development of organic hole transport materials (HTMs) for perovskite solar cells. Ze Yu received his PhD in Inorganic Chemistry at the Royal Institute of Technology (KTH), Stockholm,Sweden, in 2012, under supervision of Prof. Lars Kloo. He then joined Prof. Udo Bach’s group as a postdoctoral fellow (2012–2013) at Monash University, Australia. He is cur- rently an Associate Professor at Dalian University of Tech- nology (DUT), China. His present research interests mainly focus on the developments of hole-transporting materials for organic–inorganic hybrid perovskite solar cells, includ- ing small molecules, conducting polymers, copper ph- thalocyanine derivatives as well as inorganic p-type semi- conductors. https://doi.org/10.1016/j.jechem.2017.12.017 2095-4956/© 2018 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.