Preparation of highly oriented single crystal arrays of C8-BTBT by epitaxial growth on oriented isotactic polypropylene

Abstract

Device fabrication with organic single crystals is an important method for high device performance. High-quality organic semiconductor crystals are usually grown by a lab solution method, by which it is difficult to fabricate crystal arrays on the substrate, let alone achieve industrial production. Therefore, in this work, oriented single crystal arrays have been prepared by epitaxial growth. As an example, 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) was spin-coated on the surface of a highly oriented melt-drawn isotactic polypropylene (iPP) film on 300 nm SiO₂ substrates as an auxiliary dielectric layer, and highly oriented arrays of C8-BTBT single crystals are obtained by epitaxial growth in the solvent vapor annealing (SVA) approach. The devices based on the thus prepared C8-BTBT array have a yield of up to 81%, an average mobility of 2.5 cm² V⁻¹ s⁻¹, a maximum mobility of 9.3 cm² V⁻¹ s⁻¹ and an on/off ratio of 10⁷. Hence, our method facilitates the large-scale fabrication of highly oriented single crystal arrays with high quality, which will promote further industrial application.