Efficient thermally activated delayed fluorescent emitter based on a spiro-type benzo[b]acridine donor and a benzophenone acceptor

A novel spiro-type donor 5H-spiro[benzo[b]acridine-12,9 '-fluorene] (SPBAC) and a thermally activated delayed fluorescence (TADF) emitter bis(4-(5H-spiro[benzo[b]acridine-12,9 '-fluoren]-5-yl)phenyl)methanone (2SPBAC-BP) were synthesized for a high efficiency organic light-emitting diode (OLED). The naphthalene moiety can introduce the local excited triplet ((LED)-L-3) state into the 2SPBAC-BP molecule. (LED)-L-3 can enhance the spin-orbit coupling (SOC) between the lowest triplet excited state (T-1) and the lowest singlet excited state (S-1), working as an intermediate between the two charge transfer states ((CT)-C-3 and (CT)-C-1) for efficient triplet exciton utilization. Using this strategy, a doped film of 20 wt% 2SPBAC-BP in the PPF host exhibits a high photoluminescence quantum yield of 72%, and the organic light-emitting diode (OLED) based on 2SPBAC-BP displays a high EQE of 26.4%, a current efficiency (CE) of 86.8 cd A(-1), and a power efficiency (PE) of 85.2 lm W-1.

Automated summary

In this study, a novel organic light-emitting material, SPBAC, and a TADF emitter, 2SPBAC-BP, were synthesized for high efficiency OLEDs. The introduction of a naphthalene moiety allows for efficient triplet exciton utilization, leading to high photoluminescence quantum yield and high power efficiency for 2SPBAC-BP-based OLEDs.