Orienting Semiconducting Nanocrystals on Nanostructured Polycarbonate Substrates: Impact of Substrate Temperature on Polymorphism and In-Plane Orientation

Abstract

This paper reports a systematic investigation of the growth mechanism of zinc phthalocyanine, a p-type semiconductor, on oriented polymer substrates of bisphenol A polycarbonate (PC). It focuses on the impact of the substrate temperature on the polymorphism and the in-plane orientation of the ZnPc nanocrystals. The study combines transmission electron microscopy, X-ray diffraction, atomic force microscopy, UV–vis absorption spectroscopy, and force field-based molecular calculations. Large areas of oriented PC substrates are prepared by a simple process that combines mechanical rubbing and solvent-induced crystallization. The PC substrates show a smooth semicrystalline morphology with a preferential (a,c) surface of crystalline lamellae with a high in-plane orientation of the polymer chains. These substrates induce a unidirectional orientation of ZnPc nanocrystals with a preferred contact plane. The selection of the preferred ZnPc in-plane growth direction relies on a “self-amplified“ mechanism whereby a f...