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Enhancement in electroluminescence of PLED by optimizing coating parameters and inserting an injection layer

S. H. YANG1,* , H. J. HSIEH1, D. W. ZHUANG1, T. Y. CHEN1

Affiliation

  1. Department of Electronic Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung, Taiwan, R.O.C.

Abstract

For polymer light-emitting diode (PLED), the luminance properties of device are determined by the device structure and the morphology and thickness of the organic layer. Accordingly, this study investigates the electroluminescence (EL) enhancement of the PLED by optimizing the coating parameters and inserting an electron injection layer. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and poly(9,9-dihexylfluorene-2,7-diyl) (PDHF) were used as the conductive layer and the emission layer materials, respectively. The PLED structure was indium tin oxide/PEDOT:PSS/PDHF/Al. The low turn-on voltage and the enhanced EL intensity of the PLED were resulted from the improved carrier balance and recombination in the PDHF emission layer. When a LiF layer was inserted between the PDHF layer and the Al cathode, the EL intensity of the PLED was enhanced because of the increase in electron injection. In this condition, the maximum EL intensity of 45.8 cd/m2 at 13 V was obtained, which was 1.96 times higher than that in the case of the device without a LiF layer..

Keywords

Electroluminescence, Tunneling effect, Injection layer.

Submitted at: March 3, 2011
Accepted at: March 16, 2011

Citation

S. H. YANG, H. J. HSIEH, D. W. ZHUANG, T. Y. CHEN, Enhancement in electroluminescence of PLED by optimizing coating parameters and inserting an injection layer, Journal of Optoelectronics and Advanced Materials Vol. 13, Iss. 3, pp. 206-212 (2011)