Efficient improvement of W05‐based dyes by inserting auxiliary electron acceptors for dye‐sensitized solar cells: A theoretical investigation

To develop efficient sensitizers, five novel metal‐free dyes were designed based on one of the best dyes W05 by inserting auxiliary electron acceptors. The photovoltaic performance of new dyes was studied by density functional theory (DFT) and time‐dependent DFT (TDDFT) calculations in order to shed light on how the auxiliary electron acceptor influences on the photovoltaic performances. Results illustrated that the insertion of auxiliary electron acceptors can narrow the HOMO‐LUMO gap, red‐shift the light absorption band, and enhance the sunlight harvesting. By estimating three important photovoltaic parameters, the photoelectric conversion efficiency (PCE) of W05 was estimated to be about 8.96%, in good agreement with its experimental value of 9.22%, indicating that the scheme calculated the photovoltaic parameters is reliable. Interestingly, the estimated PCE values for designed dyes are superior to that of W05, suggesting that the molecular design is reasonable. Especially 5, its PCE was predicted to be as high as 14.07%, indicating that 5 is a promising sensitizer candidate for DSSC applications.