Such an enhancement of ICT through homoconjugation has only been noted once previously, in a structure that does not display TADF. Notably, S1 is also significantly more stabilised than T1 upon trimerization of compound 1 to 2, suggesting the iptycene core can be employed to fine-tune the ΔEST of TADF compounds. The TADF parameters of 1 and 2 were evaluated in toluene solution (Figure ). Both spectra match the PL in the same host (Table ). The 11.9% figure is larger than that reported earlier for a similar device structure. . While the larger efficiency of Dev 2 contributes to its greater maximum luminance (Dev 1 -8900 cd m -2 ; Dev 2 -14800 cd m -2 ), the other significant factor is the higher current density (Dev 1 -120 mA cm -2 ; Dev 2 -220 mA cm -2 ). Both OLEDs show a similar VON = 5.5 -6 V as 1 and 2 have nearly identical HOMO and LUMO energies.