Hole-transporting property of a chemically hybridized poly(vinylcarbazole)-fullerene

We synthesized a star copolymer of poly(vinylcarbazole) (PVK) branched from a fullerene (C60) center, and investigated its optical absorption and photoluminescence properties. The chemically hybridized PVK-C60 was then employed as a hole-transporting layer of the electroluminescent device with a poly(9,9′-dihexylfluorene-2,7-divinylene-m-phenylenevinylene-stat-p-phenylenevinylene) (CPDHFPV) emitting layer. The ITO/PVK-C60/CPDHFPV/LiF/Al device showed a strong electroluminescence quenching due to a direct contact of the PVK-C60 and the CPDHFPV layers. In contrast, when an additional PVK layer was introduced between the two layers, the electroluminescence was largely enhanced. The emitted light power of the ITO/PVK-C60/PVK/CPDHFPV/LiF/Al device was improved by ∼3 times compared with the device without the PVK-C60 layer.