Synthesis and luminescent properties of a new class of nematic oxadiazole containing poly-ethers for PLED

We report on thin films based on a new type of nematic oxadiazole containing polymer for application in blue light emitting diodes. In particular, our focus will be on the thickness and temperature dependence of the optical characteristics. A simple optical characterization setup, based on an GaN UV-LED as excitation source and a fiber-coupled spectrometer, has been used to determine the photoluminescence spectrum and peak intensity in the blue wavelength range and the UV-reflection intensity. The measured values of the photoluminescence intensity increase, while those of the UV-reflection intensity decrease strongly with increasing the thickness of the polymer film. This may enable one to use the ratio of both values after appropriate calibration as a valid tool for small variations of the film thickness. We find only a moderate decrease in photoluminescence intensity with increasing the film temperature from 25 to 60 degreesC. (C) 2004 Elsevier B.V. All rights reserved.