The initial charge-separation process in dye-sensitized solar cells (DSSC) is crucial to their efficiency. An interesting strategy is to employ donor−acceptor-π–acceptor dyes because the push–pull effect may avoid charge recombination instead of electron transfer to the semiconductor. In this work, we propose a method to design a photosensitizer based exclusively on quantum mechanics calculations. Our analysis focused on the influence of (i) different donor groups and (ii) conformational contributions, on electronic properties aiming to enhance the push–pull effect and the alignment with the conduction band. Based on this study, we propose a new dye, CAHM1, where the selected substituent have a donor character and, at the same time, enable a twisted geometry that enhances the charge separation of the first excited state. The system is characterized by a marked push–pull effect, as well as presents absorption spectrum and lowest unoccupied molecular orbital energy in a suitable region for the DSSC devices.

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