We recently demonstrated using time-resolved PL spectroscopy that higher-lying triplet states could be observed in multiple-phosphorescence emitters. Capitalizing on this design paradigm, here we utilize conjugation modulation as a tool to brighten the T 2 state of MR-TADF emitters. We report two DiKTa derivatives PhCz-O-DiKTa and PhCz-DiKTa (Figure ), and explore the impact of conjugation from the decorated donor moiety on the efficiency roll-off of the OLED (Figure ); in the conceived emitter design the degree of conjugation between 9-phenyl-9H-carbazole (PhCz) and DiKTa is employed to regulate the vibronic coupling between two triplet excited states and activate emission from the T 2 state; PhCz acts as a perturbator of the energy of the T 2 state to tune k RISC (Figure ). The F PL values as a function of doping level reveal that both emitters are reasonably resistant to concentration quenching. The existence of the T 2 state was demonstrated by time-resolved PL