The possibility of pulsed laser deposited organic thin films for light-emitting diodes

Organic films of Alq(3) and TPD, which stand as successful materials used in organic electroluminescence applications, were deposited by the pulsed laser deposition method as an alternative to traditional thermal evaporation and spin coating techniques. An organic pellet target was ablated with two wavelengths, 532 and 355 nm, of a Q-switched Nd/YAG laser at a base pressure of 2 X 10(-5) torr. Films on slide glasses were evaluated by photoluminescence, AFM, absorption spectra, and XRD to find the possibility of those films acting as organic light-emitting diodes. When 355 nm laser irradiation was used for deposition, Alq(3) and TPD films had negligible voids and were less stressed than thermal films. Even though we used a highly stressed Alq(3) pellet target, the Alq(3) film prepared by pulsed laser deposition showed a preferential structure similar to the thermally evaporated Alq(3) film. Films deposited in this experiment were more amorphous than the films fabricated by excimer lasers. (C) 2002 Elsevier Science BV All rights reserved.