Efficient full-colour organic light-emitting diodes based on donor–acceptor electroluminescent materials with a reduced singlet–triplet splitting energy gap

Abstract

The Cz-DEPVI device showed high efficiencies of L: 13955 cd m−2, ηex: 4.90%, ηc: 6.0 cd A−1, ηp: 5.4 lm W−1 and CIE coordinates of (0.15, 0.06) at 2.8 V.

Recent progress in imidazole based efficient near ultraviolet/blue hybridized local charge transfer (HLCT) characteristic fluorophores for organic light-emitting diodes

“…Researchers have used the styryl moiety as a spacer in the design strategy of the molecular structure, and it will increase the twisting nature of the molecules, and more twisting nature of the molecules push emission toward lower wavelength, due to restricting p-conjugation in the molecules. [126][127][128][129] In 2017, V. Thanikachalam et al designed and synthesized three blueemitting fluorophores, TPA-BDIS 74, TPA-BPIS 75, and Cz-BPIS 76, by connecting donor TPA/Cz and acceptor BI/PI through the styryl as a spacer (Fig. 21).…”

“…21). 129 In this designed strategy, they have directly connected the TPA/Cz donor and the PI acceptor (D–A) and integrated the PI-dihydrobenzodioxin-styryl group at the N 1 position of the D–A conjugated system. These fluorophores showed excellent thermal stability with very high glass-transition temperature.…”

Efficient donor–acceptor emitter based nonsymmetrical connection for organic emitting diodes with improving exciton utilization

“…The small inter ring torsion angle of twisted conformation suppress the intermolecular p-p stacking in solid state and thus, uorescence quenching was suppressed which leads to high h ex in lm. [29][30][31][32]…”

“…To 32 The current density versus voltage characteristics of hole-only and electron-only devices was displayed in Fig. 5.…”

Strategic tuning of excited-state properties of electroluminescent materials with enhanced hot exciton mixing

“…For nonequivalent hybridization, the S 1 and S 2 excited states have difference in energy, oscillator strength and HONTOs and LUNTOs image due to non-equivalent hybridization between LE and CT initial states. 67 Therefore, degree of hybridization between LE and CT states depends not only initial E LE -E CT energy gap but also their interstate coupling strength. 68 Compared with non-equivalent hybridization, quasiequivalent hybridization is expected to achieve the combination of high h PL and high h S to maximize EL efficiency of uorescent OLED materials due to more balanced LE and CT components in HLCT state of DPIAPPB and CADPPI.…”