Exceptionally efficient deep blue anthracene-based luminogens: design, synthesis, photophysical, and electroluminescent mechanisms

Achieving high-efficiency deep blue emitter with CIEy < 0.06 (CIE, Commission Internationale de L'Eclairage) and external quantum efficiency (EQE) >10% has been a long-standing challenge for traditional fluorescent materials in organic light-emitting diodes (OLEDs). Here, we report the rational design and synthesis of two new deep blue luminogens: 4-(10-(4'-(9H-carbazol-9-yl)-2,5-dimethyl-[1,1'-biphe nyl]-4-yl)anthracen-9-yl)benzonitrile (2M-ph-pCzAnBzt) and 4-(10-(4-(9H-carbazol-9-yl)-2,5-dimethyl phenyl)anthracen-9-yl)benzonitrile (2M-pCzAnBzt). In particular, 2M-ph-pCzAnBzt produces saturated deep blue emissions in a non-doped electroluminescent device with an exceptionally high EQE of 10.44% and CIEx,y (0.151, 0.057). The unprecedented electroluminescent efficiency is attributed to the combined effects of higher-order reversed intersystem crossing and triplet-triplet up-conversion, which are supported by analysis of theoretical calculation, triplet sensitization experiments, as well as nanosecond transient absorption spectroscopy. This research offers a new approach to resolve the shortage of high efficiency deep blue fluorescent emitters. (C) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

This study reports the rational design and synthesis of two new deep blue luminogens, achieving high efficiency deep blue emissions in non-doped electroluminescent devices. The unprecedented electroluminescent efficiency is attributed to the combined effects of higher-order reversed intersystem crossing and triplet-triplet up-conversion. This research offers a new approach to resolve the shortage of high efficiency deep blue fluorescent emitters.