Electron extraction contact in organic photovoltaic cells (OPVs) is very important to extract electrons from the active layer efficiently, improve the open-circuit voltage, and thus improve the power conversion efficiency. This paper reviews the various approaches to form an electron extraction contact for better power conversion efficiency and device lifetime, especially in organic bulk heterojunction photovoltaic cells based on conjugated polymer: fullerene blends. We discuss the roles of thin metal fluorides, a thin polymeric layer, and a solution processed metal oxide layer at the interface between the photoactive layer and the negative electrode for efficient and stable electron extraction contact in OPVs. In addition, we discuss the effects of various metallic negative electrodes in OPVs in terms of device efficiency and stability. Since these approaches are well established in organic light-emitting diodes, they can be exploited to accelerate research in device engineering to improve device performance.

有机光伏电池（OPV）中的电子提取接触对于有效地从有源层提取电子，提高开路电压并因此提高功率转换效率非常重要。本文综述了形成电子提取触点以提高功率转换效率和器件寿命的各种方法，尤其是在基于共轭聚合物：富勒烯共混物的有机体异质结光伏电池中。我们讨论了薄金属氟化物，薄聚合物层以及在光敏层和负电极之间的界面处进行溶液处理的金属氧化物层的作用，以实现OPV中有效且稳定的电子提取接触。此外，我们从器件效率和稳定性的角度讨论了OPV中各种金属负极的影响。