Carbazole dendronised triphenylamines as solution processed high Tg amorphous hole-transporting materials for organic electroluminescent devices

Abstract

Carbazole dendrimers up to 4th generation were synthesized. They showed significantly high T(g), amorphous and stable electrochemical properties, and great potential as solution processed hole-transporting materials for OLEDs. Alq3-based green devices exhibited high luminance efficiency and CIE coordinates of 4.45 cd A(-1) and (0.29, 0.53), respectively.

Novel carbazole dendronized oligofluorenes for solution-processed organic light-emitting diodes

“…The morphological behavior of these dendrimers was monitored by DSC measurements. Only one endothermic peak due to glass transition was detected at 58 C with no crystallization or melting peaks observed when a powder of G1F3 was heated for the first run, implying that G1F3 was amorphous even when it was obtained directly from organic solvents [17]. This endothermic glass transition was detected again when the super-cooled sample was subsequently reheated.…”

“…The HOMO energy levels were estimated from the onset potentials to be À5.33 and À5.29 eV for G1F3 and G2F3 respectively, according to the equation of HOMO (eV) ¼ À (E ox onset þ4.8 eV) [21]. Apparently the HOMO levels of these carbazole-based dendrimers are quite close to the work function of the ITO anode (À4.8~À5.0 eV) [17], implying that efficient hole injection at the anode/emitting layer interface could be expected when these dendrimers are used as the emitting layer of OLEDs. The energy band gaps (E g ) were determined by the absorption edge technique, and the LUMO levels were calculated by subtracting the gap from the energy of the HOMO [21].…”

Effective thermally activated delayed fluorescence emitter and its performance in OLED device

“…All deuterated solvents were purchased from Cambridge Isotope Laboratories. The compounds of 1 [10],2 [11], 4 [12], 5 [13], 6 [14], and 7 [15] were prepared according to the modified literature procedures.…”

Tetrasubstituted adamantane derivatives with arylamine groups: Solution-processable hole-transporting and host materials with high triplet energy and good thermal stability for organic light-emitting devices

“…Solution processes, such as spin coating or ink-jet printing, offer an attractive alternative approach in terms of the potential to enable low-cost and large area manufacturability that is more amenable to commercial interests [7]. Recently, some solution-processed small molecules have been demonstrated as good hole-transporting materials [8][9][10]. For example, Usluer et al reported a series of hole-transporting materials using dioctylfluorene, spirobi(fluorene) and spiro(cyclododecanefluorene) as core with different peripheral groups, which possessed high decomposition temperature (T d ) and T g values [11]; Promarak et al developed two bifunctional materials based on anthracene with the combined characteristics of deep blue light-emitting and hole-transporting ability [12]; Our group also reported a series of star-shaped compounds with the core of planar triphenylamine or hexakis (9,9-dihexyl-9H-fluoren-2-yl)benzene as solutionprocessed hole-transporting materials [13,14].…”