Theoretical studies for forecasting the power conversion efficiencies of polymer-based organic photovoltaic cells

Modifying the electron-withdrawing capability in donor-acceptor conjugated copolymers allows designing new polymers with better optical properties. These materials have been successfully applied in bulk heterojunction solar cell devices, and recently a great progress in the enhancement of power conversion efficiencies (PCE) has been achieved. In 2006 Scharber proposed a design rule to obtain PCE values over 10%, optimizing the orbital energy levels of the donor material. The present work proposes a methodology capable to predict theoretically the best efficiencies imparted by a group of 65 conjugated monomeric units selected from the literature, generating 2080 possible DA combinations. The geometries, frontier levels and optical properties were estimated by DFT methods. Based on the results, it was possible to predict the PCE of the most promising 22 copolymers. The results of the calculations indicated that several polymers investigated showed the predicted PCE between 9% and 10%. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 919-927