The excitation energies for Cz-BDT are presented in the upper panel in Fig. showing that this molecule possesses four lowenergy triplet states (red) before the first singlet state (black). Viewing the lower panel of Fig. (b), we find that T 1 is dominated by local ππ * character on the BDT core, represented in blue, with smaller Ph→BDT CT contributions (green). The corresponding NTOs are shown in panel (c) highlighting that the hole NTO (shown in blue/red) is a π-orbital on BDT with some contributions on the Ph bridge whereas the electron NTO (shown in green/orange) is a π * -orbital located right at the centre of BDT resembling the LUMO shown in Fig. . Proceeding to the next three triplet states, we find that these are a mixture of local ππ * character on BDT (blue) and nπ * character (orange) with increasing nπ * character from T 2 to T 4 . The first singlet state (S 1 ) lies just above 3.0 eV and is similar in character to T 1 albeit with more charge transfer character (red and green). This is also reflected by the dominant hole NTO, shown at the bottom in panel (c), which has extended contributions on the Ph bridges. The vertical gap between T 1 and S 1 is calculated to be 0.42 eV. The S 2 and S 3 states are locally excited states dominated by nπ * character. The S 4 state lying at 3.28 eV is a CT state which contains significant Cz→BDT character (red). For the T 5 and T 6 states, we find a mixture of state characters with roughly 40% of the excitation character attributed to local excitations on Ph and Cz.