Doped and non-doped organic light-emitting diodes based on a yellow carbazole emitter into a blue-emitting matrix.

Hakim Choukri (1) , Alexis Fischer (1) , Sebastien Forget (1) , Sebastien Chenais (1) , Marie-Claude Castex (1) , Bernard Geffroy (2) , Dominique Ades (3) , Alain Siove (1)

1 LPL - Laboratoire de Physique des Lasers
2 CEA/LITEN/DSEN - Laboratoire Cellules et Composants
3 CSPBAT - Chimie, Structures et Propriétés de Biomatériaux et d'Agents Thérapeutiques

A new carbazole derivative with a 3,3'-bicarbazyl core 6,6'-substituted by dicyanovinylene groups (6,6'-bis(1-(2,2'-dicyano)vinyl)-N,N'-dioctyl-3,3'-bicarbazyl; named (OcCz2CN)2, was synthesized by carbonyl-methylene Knovenagel condensation, characterized and used as a component of multilayer organic light-emitting diodes (OLEDs). Due to its Π-donor-acceptor type structure, (OcCz2CN)2 was found to emit a yellow light at Λmax=590 nm (with the CIE coordinates x=0.51; y = 0.47) and was used either as a dopant or as an ultra-thin layer in a blue-emitting matrix of 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (DPVBi). DPVBi (OcCz2CN)2-doped structure exhibited, at doping ratio of 1.5 weight %, a yellowish-green light with the CIE coordinates (x = 0.31; y = 0.51), an electroluminescence efficiency ΗEL=1.3 cd/A, an external quantum efficiency Ηext= 0.4 % and a luminance L= 127 cd/m2 (at 10 mA/cm2) whereas for non-doped devices utilizing the carbazolic fluorophore as a thin neat layer, a warm white with CIE coordinates (x = 0.40; y= 0.43), ΗEL= 2.0 cd/A, Ηext= 0.7 %, L = 197 cd/m2 (at 10 mA/cm2) and a color rendering index (CRI) of 74, were obtained. Electroluminescence performances of both the doped and non-doped devices were compared with those obtained with 5,6,11,12-tetraphenylnaphtacene (rubrene) taken as a reference of highly efficient yellow emitter.

Mots clés: OLED; doped and non-doped devices; white emission

Domaines: Optique [physics.optics]

Hakim Choukri, Alexis Fischer, Sebastien Forget, Sebastien Chenais, Marie-Claude Castex, et al.. Doped and non-doped organic light-emitting diodes based on a yellow carbazole emitter into a blue-emitting matrix.. Synthetic Metals, 2007, 157, pp.198-204. ⟨10.1016/j.synthmet.2007.01.005⟩. ⟨hal-00125481v2⟩