Block-Copolymer-Nanowires with Nanosized Domain Segregation and High Charge Mobilities as Stacked p/n Heterojunction Arrays for Repeatable Photocurrent Switching

Abstract

Development of materials for efficient photoenergy conversion is a subject of critical importance in current science and technology. Efficient performance requires well-controlled segregation of electron donor and acceptor moieties, which we have achieved using block copolymers of tetraphenylporphinatozinc(II) (donor) and C(60) fullerene (acceptor) using living ring-opening metathesis polymerization (ROMP). The resulting amphiphilic ROMP block copolymers undergo self-assembly into nanostructured phase-segregated 1-dimensional nanowires with an approximately 5.5 nm periodicity zebra-stripe-like morphology simply by drop-casting solutions of the polymers onto a substrate such as mica or highly oriented pyrolytic graphite (HOPG). Thin films of the self-assembled nanophase-segregated copolymers exhibit high charge carrier mobilities (approximately 0.26 cm(2) V(-1) s(-1)) and electrical conductivities (up to 6.4 x 10(-4) cm(2) V(-1) s(-1)) as well as highly repeatable photocurrent switching with rapid ON/OFF responses upon white light irradiation.