We have prepared top-illuminated organic photovoltaic devices on stainless-steel substrates, using molybdenum trioxide/indium tin oxide as the transparent top electrode. Incorporating an Al counter electrode grid having a shadow fraction of 10% effectively reduced the device resistance, thereby enhancing the power conversion efficiency to ca. 3%. This device exhibited superior mechanical flexibility. The inverted device architecture eliminated the need to use low-work-function metals, which are air sensitive and easily oxidized, thereby improving the air stability of the flexible devices.