Synthesis and characterization of novel 2,7-carbazole derivatives for blue light-emitting diodes

Abstract

Two 2,7-carbazole based low molecular weight derivatives, 9-hexyl-N 2 ,N 2 ,N 7 ,N 7 -tetraphenyl-carbazole-2,7-diamine (TPCA) and 9 0 -hexyl-9 0 H-9,2 0 :7 0 ,9 00 -tercarbazole (HTC), were synthesized by Buchwald and Ullmann coupling reactions, respectively. The optical, electrochemical and thermal properties of this two analogous small molecule hosts have been characterized. The HOMO level of TPCA and HTC were -5.25 and -5.29 eV indicating good hole-transporting properties. Both of the compounds emit deep blue light peaked at 410 and 428 nm in solid state. According to the measurement, the luminescence quantum yield of TPCA is 0.98, almost 1.7 times higher than that of HTC (0.59) in dilute THF solution. The geometrical and electronic properties of the compounds were studied using density functional theory calculations. The studies mentioned above indicate that both TPCA and HTC are suitable for active materials of blue light-emitting diodes.

Synthesis and properties of hyperbranched polymers for white polymer light-emitting diodes

“…2 . The absorption bands at around 365 nm are due to the π–π* transitions of poly(fluorene- alt -carbazole) backbones, 24 which are blue-shifted about 15 nm compared with the fluorene-based hyperbranched polymer with SDF of 10 mol%. This notable hypochromatic shift is attributable to the interruption of the conjugation of the copolymer backbone by the introduction of the 3,6-carbazole linkage.…”

2,7(3,6)-Diaryl(arylamino)-substituted Carbazoles as Components of OLEDs: A Review of the Last Decade

“…The compounds 27DBrCr, 36DBr9ArCr, or 36DI9ArCr were firstly obtained as starting materials for the synthesis, as shown in Scheme 1. The target compounds E21 [100,101] and E23 [102] were obtained during the Buchwald-Hartwig amination reaction, and the materials E22 [79], E24 [103], and E25 [104] were obtained during the Ullmann reaction of the starting derivatives.…”

Photo and electroluminescence of a solution processable silane modified Alq3 composite showing bluish green emission

“…Flexibility, large area emitting and high efficiency are the most important keys for developing interests to make such systems [4][5][6]. Attempts have been recently done on the synthesis and use of a variety of novel electroluminescent (EL) materials for the construction of reliable OLEDs which can be highly suitable in different aspects like quantum efficiency, charge carrier mobility, thermal stability and processability [7][8][9]. Among small molecules being used in OLEDs construction, tris (8-hydroxyquinolinato) aluminum known as Alq3, is one of the most known materials due to its properties that make it applicable as the electron injection layer and EL layer [10][11][12].…”