A universal bipolar host based on isonicotinonitrile and carbazole for efficient red, green and blue PhOLEDs?

New Journal of Chemistry Pub Date: 2022-07-15 DOI: 10.1039/D2NJ02652J

Abstract

Full colour display is vital to organic lighting-emitting diodes (OLEDs) and universal hosts for all red, green and blue (RGB) OLEDs are strongly desired. In this work, a universal bipolar host, namely BCz3PhCN, was synthesized by simply incorporating carbazole and isonicotinonitrile units. BCz3PhCN exhibits excellent thermal stability and a high triplet energy level (ET) of 2.76 eV; therefore, all RGB devices were fabricated to evaluate their electroluminescent (EL) performance. The blue device hosted by BCz3PhCN was lit at 3.0 V with the maximum external quantum efficiency (EQEmax) of 16.22%. Green PhOLEDs exhibited a better performance with the maximum luminance (Lmax) of 1?21?900 cd m?2, maximum current efficiency (ηc,max) of 69.30 cd A?1, maximum power efficiency (ηp,max) of 64.88 lm W?1 and EQEmax of 20.04%. Remarkably, the highest EQEmax of 26.84% was achieved by the red device in the low luminance range. The above excellent EL performance for all BCz3PhCN-based blue, green and red devices indicates a huge potential for BCz3PhCN as a universal host in developing high-performance monochrome and white OLEDs.

Graphical abstract: A universal bipolar host based on isonicotinonitrile and carbazole for efficient red, green and blue PhOLEDs
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