Photovoltaic technology is a promising choice for human beings to solve critical environmental and energy problems.Much effort has been expended around the world on this technology which has allowed it to flourish, both in power conversion efficiency (PCE) and market share in the global energy supply sector.In this scenario, not only has mature silicon (Si) solar cell technology evolved to become much more cost-effective and more efficient for solar energy conversion, but new technologies with high PCE and low cost have also been refined.During the last ten years,the rapid development of perovskite solar cells has surprised and motivated many researchers, who made perovskite solar cells the hottest topic at the 29th International Photovoltaic Science and Engineering Conference (PVSEC29) in Xi'an (Fig.1).