Conceptual drawing shows a flexible organic photovoltaic made from an acceptor of PCBM (buckyball with earth) and the donor of deuterated conducting polymer. The polymer blend in the device (bottom) will harvest the sunlight to generate electrical power. (carbon: blue; sulfur: yellow; hydrogen: white; deuterium: purple). PCBM is the common abbreviation for the fullerene derivative phenyl-C61-butyric acid methyl ester. It is an electron acceptor material and is often used in plastic solar cells or flexible electronics in conjunction with electron donor materials such as P3HT or other polymers.