OPVs with a conventional structural orientation are illuminated at the bottom through a transparent anode, such as indium tin oxide (ITO), and electrons are collected on a low work function metal cathode on top. Inverted OPVs use ITO as cathode material and low work function metal substances as anode material instead. Inverted OPVs have several benefits: they may 1) provide more degrees of freedom in designing OPV fabrication schemes, 2) allow for protection of the delicate organic semiconductor layers below the anodic buffer layers, and 3) be more stable by allowing use of higher work function metal top contacts. However, ITO has a high work function and makes a poor cathodes by itself. In order to increase the efficiency of an inverted OPV, a low work function (LWF) cathode buffer layer must be developed to provide a sufficient electric field throughout the device.