High-efficiency and low-efficiency roll-off fluorescence/phosphorescence hybrid white organic light-emitting diodes based on AIEgens with hot exciton property by strategically managing triplet excitons

Abstract

Aggregation-induced emission (AIE) materials can be well utilized to fabricate high-efficiency blue fluorescence organic light-emitting diodes (OLEDs) due to their fast reverse intersystem crossing (hRISC) from the high-lying triplet state (T_n ≥ 2) to low-lying singlet state (S₁) and high photoluminescence (PL) quantum efficiency in the solid film, which should be conducive to the preparation of high-efficiency white OLEDs (WOLEDs). In this study, we fabricated high-efficiency two-color and four-color hybrid WOLEDs based on an AIEgen of 4′-(4-(diphenylamino)phenyl)-5′phenyl-[1,1′:2′,1′′-terphenyl]-4-carbonitrile (TPB-AC) as the blue emitter and host of yellow phosphor, and the efficiency and efficiency roll-off were greatly improved by incorporating a triplet–triplet fusion (TTF) layer in the TPB-AC blue emitter. Finally, the two-color WOLED exhibited a low turn-on voltage of 2.6 V, and the maximum EQE, CE, and PE of 23.2%, 73.2 cd A⁻¹, and 78.7 lm W⁻¹, respectively. The CE, PE, and EQE were maintained at 21.1%, 63.2 cd A⁻¹, and 58.3 lm W⁻¹, respectively, at the luminance of 1000 cd m⁻², achieving an extremely low-efficiency roll-off. The optimized four-color hybrid WOLED also showed the maximum EQE, CE, and PE of 24.9%, 49.6 cd A⁻¹, and 51.9 lm W⁻¹, respectively, with low-efficiency roll-off and CRI was over 85. Our results fully demonstrate the potential application value of AIEgens in the preparation of high-performance WOLEDs.