Designing Polymers for Photovoltaic Applications Using ab Initio Calculations

This article evaluates the efficiency, of density functional theory calculations when used in conjunction with Scharber's model to predict the power conversion efficiency of organic solar cells. Thirty polymers were investigated, and their calculated electronic properties were assessed against their reported experimental values. The energy level calculations have a relatively small standard deviation of about 0.2 eV after a correction for a systematic overestimation. The optical band gap and the open-circuit voltage are obtained within an accuracy of 0.09 eV and 0.10 V, respectively. Also, the model provides an indication of the maximum value for the short-circuit current and an interesting guiding tool to identify promising suitable polymers to reach high power conversion efficiencies. After validating the present numerical approach against known devices, new polymers that could reach a power conversion efficiency ranging from 8 to 11% are presented.