Characterizing the Morphology and Efficiency of Organic Solar Cells by Multiscale Simulations

High-efficient photovoltaic devices based on organic-conjugated polymers have attracted tremendous attentions in the past few decades thanks to their low-cost and flexibility. Theoretical and experimental understandings of the structure–property relationship are needed to further enhance the power conversion efficiency of devices. Herein, a multiscale simulation method, combining dissipative particles dynamics and graph theory, is adopted to simulate the morphology evolution of bulk heterojunction active layer and correlate an efficiency indicator to characterize the performance of polymer solar cells by graph theory. The effects of molecular weight, side chain length, annealing temperature, solvents, and additives are investigated in the poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61 butyric acid methyl (PCBM) system. Our simulation results indicate that the mixture of P3HT with a molecular weight of 24 K g/mol shows the optimal morphology and efficiency indicator when annealing temperature is at 153 °C. It is found that our multiscale simulation results agree well with the experimental observation, providing a quantitative and qualitative description of the relationship between morphology and performance.