Precise control over reduction potential of fulleropyrrolidines for organic photovoltaic materials
Organic photovoltaic cells based on two types of organic materials (acceptor and donor) have attracted considerable attention for their low cost fabrication, and potential for realization of flexible and light weight devices. For many years organic photovoltaic cells have relied on [6,6] phenyl C61 butyric acid methyl ester, a fullerene derivative that is used as an electron acceptor material. A few reports on bisadduct and C70 derivatives have shown some improvements in device performance; however, further enhancements based on improvements to the fullerene acceptor component have proven challenging. Here we described the device performance of improved acceptor fullerene materials that allow the open circuit voltage to be fine tuned in organic photovoltaic cells to provide high power conversion efficiency. Our new approach to designing fullerene materials will accelerate development of n type semiconductor materials and allow for new low cost organic photovoltaic cells.