A New Class of Solution Processable Pyrazino[2,3‐g]quinoxaline Carbazole Derivative Based on D–A–D Architecture for Achieving High EQE in Yellow and White OLEDs

Abstract A new pyrazino[2,3‐g]quinoxaline carbazole derivative with branched alkyl peripheral chains PQC‐12b with a donor–acceptor–donor nonplanar architecture is reported. PQC‐12b exhibits high molar extinction coefficients, low bandgap, bright emission behavior in solution and solid‐state, along with positive solvatochromism. PQC‐12b is used in organic light‐emitting diodes (OLEDs) either as sole emissive material or as a guest in different host materials. Amongst these different host–guest OLEDs, CBP‐based device with the optimized concentration of PQC‐12b shows maximum values for power efficacy (PE_max) of 14.1 lm W⁻¹, current efficacy of 26.8 cd A⁻¹, external quantum efficiency (EQE_max) of 8.0%, and lifetime of 5.1 h at an initial luminance of 5000 cd m⁻² with a low power efficacy roll‐off and roll‐up character in current efficacy and EQE. A triplet exciton harvesting approach is employed by incorporating thermally activated delayed fluorescent emitter 4CzIPN to obtain a PE_max of 33.4 lm W⁻¹, a CE_max of 56.3 cd A⁻¹, an EQE_max of 15.3%, and a maximum luminance (L_max) of 29 400 cd m⁻². Utility of the compound in solution‐processable white OLED is explored and interestingly showed a PE_max of 42.2 lm W⁻¹, a CE_max of 40.3 cd A⁻¹, an EQE_max of 12.0%, and L_max of 24 667 cd m⁻².