Preparation of Organic Semiconductive Thin Films by Laser Ablation

Control of Structure and Electric Properties by Selecting Wavelength, Fluence and Substrate Temperature

Abstract

Amorphous organic semieonductive thin films with electric conductivities ranging between 10^-5 and 10¹ Scm^-1 are prepared on several temperature-controlled substrates by cxcimcr laser ablation (ELA) of 3, 4, 9, 10-pcrylenetetracarboxylie dianhydride (PTCDA), with 193nm (ArF), 248nm (KrF) and 308nm (XeCI) beams. The structure, electric conductivity and carrier species of the films prepared strongly depend on the ablation wavelength, fluence and substrate temperature. In thermoelectric power measurements, conversion of carrier species from n-type to p-type is observed with increasing fluence of a 308nm beam from 0.2 to 4.0 Jcm^-2pulse^-1. A film prepared on a substrate at 300°C by ELA with a 308nm beam partially contains polyperinaphthalene (PPN) structure with electric conductivity of 10^-2-10^-1 Scm^-1.