Novel electro-fluorescent materials with hybridized local and charge-transfer (HLCT) excited state for highly efficient non-doped pure blue OLEDs

Abstract

Pure blue emitters have become a research hotspot in the field of organic light-emitting diodes (OLEDs). Achieving high-performance pure blue OLEDs is still a challenge from the perspective of molecular...

Oxygen heterocyclic coumarin-based hybridized local and charge-transfer deep-blue emitters for solution-processed organic light-emitting diodes

“…The single-component and nanosecond-scale lifetimes can exclude their possibility of being used as TADF or triplet–triplet annihilation (TTA) materials. 30 Hence, the HLCT properties of BCz-6P , p Ph-6P , and o Ph-6P can be affirmed, taking into account their nanosecond-scale lifetimes and solvatochromic behaviors observed in different solvents.…”

“…11,[17][18][19][20][21][22] However, most of them are developed from nitrogen heterocyclic acceptors, particularly imidazoles, such as benzoimidazole, naphthimidazole, and phenanthro [9,10d]imidazole. [23][24][25][26][27][28][29][30] Consequently, developing additional superior acceptors is crucial for broadening HLCT material systems and achieving high-efficiency OLEDs.…”

An efficient blue electro-fluorescence material with high electron and balanced carrier mobilities based on effective π-stacking between acceptors

“…[16][17][18][19][20] Carbazole derivatives with broadband gaps and phenanthrimidazole derivatives with bipolar transport are common weak donors used to construct HLCT-based blue fluorophores. [21][22][23][24][25] Their high rigidity can suppress low luminescence efficiency caused by non-radiative transitions. 2,5-Diphenyl-1,4,5-oxadiazole (DPO) is an excellent electronic transmission material owing to its well-known electron transport behavior, 26,27 and its natural large planarity is expected to form π-stacking in molecules.…”

Highly efficient deep-blue organic light-emitting diodes (OLEDs) based on hot-exciton materials with multiple triplet exciton conversion channels

“…1,2 Deep-blue electroluminescent materials can expand the color gamut and lead to the development of full color OLED displays, 3,4 and hence obtaining deep-blue emitters with high external quantum efficiencies (EQEs) has become a key scientific issue. According to the formula EQE = γ · η out · Φ PL · η r (where γ is the recombination efficiency of holes and electrons, and γ = 1 if full electron–hole recombination is assumed; η out is the light out-coupling efficiency, and 0.2 ≤ η out ≤ 0.3 is assumed for a glass substrate; Φ PL is the photoluminescence quantum yield in the solid state; and η r is the exciton utilization efficiency), 5 Φ PL and the exciton utilization efficiency play a decisive role in determining the level of EQE. How to improve EQE means how to improve Φ PL and η r simultaneously.…”