Recent progress of flexible perovskite solar cells

Perovskite solar cells (PSCs) have been regarded as a promising new generation photovoltaic technology for their high power conversion efficiency, facile fabrication and low cost. Flexible perovskite solar cells (FPSCs) are supposed to be the foremost commercialization option of PSCs because the devices can be prepared by roll-to-roll printing process and suitable for mass production. More importantly, FPSCs prepared on ultrathin and lightweight substrates can meet the demands from the emerging market of flexible electronics and find applications that cannot be achieved with conventional photovoltaic devices. So far, many breakthroughs of FPSCs have been reported and efficiency over 21% has been achieved. In this review, the recent progress of FPSCs is described in details. Many critical issues, including device design, substrates, perovskite materials, electrode materials and charge transport layers, are elucidated and discussed comprehensively. Finally, conclusion and outlook for this field are addressed.