Pyrrolo[1, 2‐a]quinoxaline‐Based Bipolar Host Materials for Efficient Red Phosphorescent OLEDs

Abstract

Novel bipolar host materials 4CBZ-PQ, 3CBZ-PQ and TPA-PQ based on carbazole, triphenylamine as electron donors and pyrrolo[1, 2-a]quinoxaline as an electron acceptor unit has been synthesized and characterized. Their photophysical, thermal and electrochemical properties have also been investigated. These structures show suitable frontier molecular orbital (FMO) energy levels and ensure good thermal and morphological stability. Amongst these bipolar host materials, 4CBZ-PQ showed high T g (155.7 o C) and T d (160.7 o C) as well as good triplet energy (E T ) of 2.59 eV. Hence, phosphorescent organic light-emitting diodes (PhOLEDs) were fabricated containing 4CBZ-PQ, 3CBZ-PQ and TPA-PQ as host materials. 4CBZ-PQ showed best EL performance with a turn-on voltage of 2.6 V, a maximum brightness of 100388 cd/m 2 , a maximum current efficiency of 18.1 cd/A 1 , a maximum power efficiency of 12.9 lm/W and an external quantum efficiency of 15.1%. The RBY (red, brown and yellow) three-color PhOLED with 4CBZ-PQ as the host material showed maximum external quantum efficiency of 15.1% for the red device, indicating its potential utility as a host material for highly efficient PhOLEDs. state molecular geometries and experimental section of 4CBZ-PQ, 3CBZ-PQ and TPA-PQ.

Efficient synthesis of pyrrolo[1,2-α]quinoxalines mediated by ethyl 2-(4-nitrophenyl)azocarboxylate

“…12 In addition, several 4-aryl substituted pyrrolo[1,2-α]quinoxalines showed interesting fluorescence and photophysical properties. 13…”

Exciplex forming a Phenyl-Spaced Phenoxazine D–A Cohost for a Highly Efficient Red-Phosphorescent Organic Light-Emitting Diode

“…Our group has made a fair contribution to the development of bipolar materials for the emissive layer (EML) of OLEDs . By using a reaction scheme consisting of C–C and C–N coupling reactions following classic carbonyl chemistry, we have synthesized pyrroloquinoxaline, , benzothiadiazine-1,1-dioxide, ,, and benzimidazole derivatives as acceptors in π-conjugated bipolar scaffolds. Interestingly, we observed that a rodlike shape of the donor–acceptor (D–A) units in the bipolar molecules proved to be more efficient. , We subsequently synthesized many such molecules with good electroluminescent efficiencies in devices. , The advantages of a rod-shaped design of molecules was twofold.…”

“…Interestingly, we observed that a rodlike shape of the donor−acceptor (D−A) units in the bipolar molecules proved to be more efficient. 10,11 We subsequently synthesized many such molecules with good electroluminescent efficiencies in devices. 8,12 The advantages of a rod-shaped design of molecules was twofold.…”

Recent Progress in the Catalytic Synthesis of Pyrrolo[1,2‐α]quinoxaline

“…As an important class of nitrogen heterocyclic compounds, pyrrolo[1,2‐ α ]quinoxalines and their derivatives, contain two six‐membered rings and one five‐membered ring in their structures, and have excellent biological activities for compounds containing a pyrrolo[1,2‐ α ]quinoxaline fragment, such as anticancer, [1a] antitumor, antimalarial, [1b] inhibition of protein tyrosine phosphatase 1B, [1c] activation of Sirt2‐7, [1d] inhibition of the D‐ring activity of RAD51, [1e] etc. In addition, the three rings form a highly conjugated plane with large rigidity and exhibit extremely strong fluorescence, [2] and their modification by using different groups can modulate fluorescence of different colors, which can be used in organic electroluminescence, [3] chemical sensing detection, [4] fluorescent probe design, [5] etc, shown in Figure 1, therefore, the rapid construction of pyrrolo[1,2‐ α ]quinoxalines fragment is particularly important.…”