A locally excited and optically dark S 1 minimum certainly runs counter to the initial design strategy of using a D-π-A-π-D system and may well explain the poor performance of Cz-BDT in TADF applications. To further test this hypothesis, we have spent some effort in searching for a different local minimum on the S 1 energy surface that might have enhanced CT character considering two strategies: (i) pre-optimisation with the PBE functional before starting the ωPBEh optimisation and (ii) optimisation of S 2 . Neither of these strategies led to the location of an S 1 minimum with enhanced CT character and we conclude that, indeed, the excitation localises on the Ph-BDT-Ph part upon excited-state relaxation. Furthermore, we find that inclusion of state-specific solvation using the toluene solvent only has a minor overall effect of the energies. All energy shifts are below 0.01 eV and the state characters and exciton sizes virtually unaffected suggesting that the conclusions made are robust with respect to the specifics of the solvation model used.