Incorporating a tercarbazole donor in a spiro-type host material for efficient RGB phosphorescent organic light-emitting diodes

摘要

The exploitation of universal spiro-type hosts suitable for full-color phosphors is still a bottleneck for fabricating highly efficient phosphorescent organic light-emitting diodes (PHOLEDs) with a similar device structure. In this work, a novel spiro-configured host 3,6-di(9H-carbazol-9-yl) spiro[indolo[3,2,1-de] acridine8,90- thioxanthene] 100,100-dioxide (TCZSO2) incorporating 90H-9,30: 60,900-tercarbazole and 9H-thioxanthene 10,10-dioxide moieties is designed and synthesized. Utilizing 90H-9,30: 60,900-tercarbazole as the buildingblock in designing new spiro-type host materials in organic light-emitting diodes (OLEDs) is seldom reported. In particular, the three color-based devices based on TCZSO2/bis(4,6-(difluorophenyl) pyridinatoN, C20) picolinate (FIrpic), TCZSO2/iridium(III) bis(2-phenylpyridinato-N, C20) acetylacetonate (Ir(ppy) 2(acac)) and TCZSO2/iridium(III) bis(2-methyldibenzo[f, h] quinoxaline) acetylacetonate (Ir(MDQ) 2(acac)) exhibit respectable external quantum efficiencies (EQEs) of 22.8%, 24.0% and 21.0%, respectively. More encouragingly, blue and green PHOLED devices have quite low efficiency roll-off (EQE: 22.7%/24.0%, FIrpic/Ir(ppy) 2(acac)) at a high brightness of 1000 cd m 2. At a higher brightness of 5000 cd m 2, there is only 5.3% and 4.6% decrease in EQEs from their maximum values, indicating a very low efficiency rolloff. These excellent results confirm a novel spiro-type host design strategy for incorporating reported electron donors with high triplet energy (ET) to achieve high-performance RGB PHOLEDs.