Abstract:Polymer-fullerene bulk heterojunction solar cells (PSCs) have attracted much attention due to their potential applications in flexible, lightweight, and large-area devices based on low-cost solution process. Efficient treatment of the cathode interface in PSCs can both improve the extraction and collection of charges and improve the power conversion efficiency of the device. The proper choice of interface material is very important for highly efficient and stable organic photovoltaic devices and has become a significant research topic of organic photovoltaic. In this paper, different methods, principles, and recent progresses in cathode treatment of PSCs are summarized, also the problems and status are summerized.