科研之友
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摘要
The blue OLED material plays a vital role in the field of electroluminescence. Based on high-energy excited state transition， the “hot exciton” materials show the potential of excellent blue light emitting. We designed and synthesized a novel D-π-A structure molecule TACN using anthracene as the core building unit， triphenylbenzene as the weak donor and phenylcyanogen as the acceptor by adjusting the ability of pushing and pulling electrons. Distorted triphenylbenzene provides a highly distorted molecular conformation， which effectively attenuates the quenching effect in the aggregated state. Therefore， TACN exhibits a high fluorescence quantum yield （47% in the aggregated state）. The experimental results and theoretical analysis show that TACN has the “hot exciton” characteristic， and its large T2-T1 gap （1.45 eV） effectively hinders the internal conversion （IC） process from T2 to T1， while its small T2-S1 energy difference （0.18 eV， T2> S1） facilitates the reverse intersystem crossing （RISC） process. Non-doped devices based on TACN exhibit dark blue emission （λmax= 444 nm）， full width at half maximum （FWHM） of 59 nm， and color coordinates of （0.17， 0.13）. Its maximum external quantum efficiency （EQEmax） is 8.3% and corresponding exciton utilization （EUE） is up to 88.7%. ? 2023 Chines Academy of Sciences.
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