The effect of PCBM doping on the electroluminescent performance of organic light-emitting diodes

In this paper, the devices with and without electron-injecting layer (EIL) are fabricated. The effect of [6,6]-Phenyl C-61 butyric acid methyl ester (PCBM) doping in the hole transport layer poly(9-vinylcarbazole)(PVK) on the electroluminescent performance of organic light-emitting diodes is investigated by changing the PCBM content from 0 to 3%. A simple and efficient method is presented to improve the hole-mobility of organic light emitting devices by doping PCBM into PVK which facilitates the hole injection and transport, and leads to a low driving voltage with a high luminance in both series of devices. The higher the PCBM concentration is, the higher the efficiency of the doped devices with EIL over the entire investigated PCBM concentration is. However, in the devices without EIL an appropriate concentration (1%) results in a higher efficiency. The balanced carrier in the doped devices with EIL is better than that in other devices. This leads to the improvement in the luminance and current efficiency. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim