Preparation of Organic Light-Emitting Thin Films by Pulsed Laser Deposition

Abstract

Organic thin films such as Alq3, TPD and PVCz used for an organic electroluminescence (OEL) devices were prepared by pulsed laser deposition (PLD) technique using one of fundamental (λ=1064 nm) or second harmonic (λ=532 nm) of a Nd: YAG laser and a KrF excimer (λ=248 nm) laser. Both Alq3 and TPD films deposited by using Nd: YAG laser showed photoluminescence (PL) spectra similar to those of the targets, which have peaks of 525 nm and 420 nm, respectively. However clear PL could not be seen in the films by KrF excimer laser. Structural compositions of the Alq3 and TPD films depended on the laser wavelength. According to photon energy of a laser light, deposition process using Nd: YAG laser were dominated by the thermal effect, while the process using KrF excimer laser was influenced by a photochemical reaction.NVCz films were grown by pulsed Nd: YAG (532 nm) laser deposition method using the monomer NVCz target at the laser fluence of 300 mJ/cm2. The NVCz films had absorption spectra indicating the polymeric molecular structure similar to the spin-coated PVCz film. This research suggests the possibility of the polymer film formation using PLD process without heating and the initiator.