IR absorption anisotropy in perylene-3,4,9,10-tetracarboxylic acid dianhydride

Abstract

Introduction. Organic semiconducting materials are currently widely employed in the production of functional instruments and devices such as organic transistors and microcircuits, solar cells, light-emitting diodes and electroluminescent displays, radio-frequency ID chips, electronic paper, etc. [1]. Semiconducting materials based on perylene derivatives, which are aromatic compounds, are some of the most common ones and are used as dyes in the textile industry. The optical and electric properties of these materials are comparable with those of inorganic broad-band semiconductors. Perylene-3,4,9,10-tetracarboxylic acid dianhydride (PTCADA) is a special base molecule among perylene derivatives. Like most perylene derivatives, materials based on PTCADA are typically anisotropic and, therefore, have anisotropic physicochemical properties. For example, the conductivity parallel and perpendicular to the orientation axis of molecular PTCADA crystallites can differ by six orders of magnitude [2]. The optical properties of PTCADA are also strongly anisotropic [3]. A study of the anisotropy of the structure and properties suggests ways of using it to fabricate functional devices based on perylene derivatives. Herein the specifics of IR absorption anisotropy in the region 700–900 cm –1 for various incident angles of radiation relative to the substrate normal are studied.