For PTZ-DBTO2 in PYD2, a Stoke's shift of 1.04 eV is reported here, greater than that of CBP, which agrees with the general trend of solvatochromism, that is, the Stoke's shift increases as the solvent polarity increases. This is again in contrast with previous work, 15 which showed no Stoke's shift at all, where the authors argue that this is due to the rigidity of PYD2 which provides a tightly packed molecular environment and hence demonstrated earlier, in Table , energies calculated using pure TD-DFT and TD-DFT+TDA show no significant difference. Furthermore, the results shown in Figure agrees with previous work 15 that emission energies are stable after ∼ 50 ns, especially for the solid hosts PYD2 and CBP, since the reorientation of the hosts are restricted on this time scale.