Efficient inter-molecular energy transfer via dye-dopants in poly(methylphenylsilane) based electroluminescent devices

Abstract

Orgaric electroluminescent devices, comprised of polymer host (poly(methylphenylsilane)) and dye dopants (perylene and 4-dicyanomethylene-6-cp-julolidinostyryl-2-tert-butyl-4H-pyran; DCJTB), have fabricated and characterized to investigate the intermolecular energy transfer. The device has configuration of indium-tin-oxide (ITO) anode a buffer layer of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) (30 nm), emitting layer of PMPS 1 wt% of THF: dye dopant with a mole ratio of 0.1-1.0% (60nm) and an electron transporting layer of tris(8-hydroxyquinoline) aluminum (Alq(3)) (20 nm) and LiF (0.5 nm) At cathode (100 mn). Energy transfer mechanism between PMPS and dye dopants was studied by absorption, photoluminescence and electroluminescence spectra. Current-voltage-luminance (I-V L) characteristics of the devices were also discussed. The polysilane based organic electroluminescent diodes exhibited a maximum external quantum efficiency of 0.87% and a maximum luminous efficiency of 0.36 lm/W and luminance of 890 cd/m(2) (at a driving voltage of 21 V). The excitation energy was transferred from the polysilane to the dye dopants efficiently and the energy matching between polymer and dopants was the most important factor in fabricating the EL devices through the simple wet processes for the dye-dopants electroluminescent devices. (C) 2004 Elsevier B.V. All rights reserved.