A simple strategy for obtaining aggregation-induced delayed fluorescence material achieving nearly 20% external quantum efficiency for non-doped solution-processed OLEDs

The development of efficient non-doped organic luminescent materials is challenging work due to the existence of aggregation-caused quenching (ACQ) effect in most of emitters. Here, 1,10-phenanthroline (Phen) with a rigid structure was selected as acceptor unit, which could well limit intramolecular vibrations and rotations. According to the Ullmann coupling, the twisted tert-butyldiphenylamine-modified carbazole named N³,N³,N⁶,N⁶-tetrakis(4-(tert-butyl)phenyl)-9H-carbazole-3,6-diamine (tBuPhACz) was introduced into 2, 9-position of the Phen to afford tBuPhACz-Phen as target material, which not only can limit the π–π stacking of acceptor, but also could obtain the TADF and AIE effects due to the twisted D-A structure. The non-doped neat film of tBuPhACz-Phen shown high photoluminescence quantum yield (PLQY) of 76.5 %. The non-doped solution-processed electroluminescent devices obtained high performance with the maximum external quantum (EQE_max) up to 19.7 %. This result illustrated that the performance of this device is one of the best in the non-doped solution-processed OLEDs.