Changing organic electroluminescent color by the voltage applied

Organic electroluminescent (EL) devices with one layer of Alq(CH3)(2) doped with poly(N-vinylcarbozle) (PVK) (Alq(CH3)(2)/PVK) as the EL-emitting laye r sandwiched between indium tin-oxide (ITO) and aluminum electrodes have be en fabricated by spin coating on to ITO. We found that two EL-peak intensit ies at the position of 520 nm from Alq(CH3)(2) and at 470 nm from PVK chang e with different voltages applied to the organic EL devices. According to t he analysis of the experimental results, it could be inferred that a charge transfer from Alq(CN3)(2) to PVK may take place in the Alq(CH3)(2)/PVK mix ed film, leading to a much increased the EL intensity of the peak (lambda = 470 nm) from the PVK and a slight increase in the EL intensity of the peak (lambda = 520 nm) from Alq(CH3)(2) with the voltage elevation at the highe r voltages applied. (C) 1998 Elsevier Science Limited. All rights reserved.