The excitation energies of 13 BODIPY dye sensitizers are benchmarked by means of TD-DFT, using 36 functionals. Spin-component-scaled double-hybrid (DSD) functionals are found to show the best performance.

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The absorption spectra modeled as the vertical excitation energies of 13 dye sensitizers used in dye-sensitized solar cells (DSSCs) are benchmarked by means of time-dependent (TD)-DFT, using 36 functionals from...

A series of 16 BODIPY dye for DSSC applications are designed with the aim of obtaining a controlled red-shift of their absorption band maxima. The design is based on changing the number and position of the substituted methyls at the BODIPY moiety. The excited-state properties of the proposed molecular dyes were predicted with the TD-B2PLYP/def2-TZVP level. In going from the fully methyl substituted dye (D1357) to the unsubstituted one (D0) where all the methyls are replaced by hydrogens, a gradual red-shift of the lowest and most intense electronic excitation was observed (reaching a max. of 0.8 eV ≈ 220 nm) which resulted from lower HOMO-LUMO gaps and higher conjugation. The tuning function of the methyls on the electronic spectra and other relevant properties of these chemical moieties is carefully analyzed. Replacing the methyls with hydrogens was also found to induce more significant charge-transfer character, as indicated by natural transition orbital (NTO) and electronic structure analysis, enhanced excited-state life-times, and electron transport abilities, while slightly reduce the calculated light harvesting efficiency and the free-energy of electron injection ΔG inj .