An ESR Study of Photoinduced Charge Transport in the Polymer/Fullerene System

摘要

Conjugated polymers and their composites with fullerenes hold promise for molecular electronics, e.g.,as an active matrix of plastic photovoltaic devices [1, 2]. Methyl 6,6-phenyl-C61 -butanoate (MPCB), a fullerene derivative, introduced into poly-3-dodecylthiophene (P3DT) forms the so-called bulk heterojunction with the polymer matrix and acts as an electron acceptor. When such a heterojunction is illuminated by visible light, electron detachment from the polymer chain and its transfer to a fullerene molecule take place [3]. This process is accompanied by the formation of a radical pair, the positively charge polaron P and the negatively charged fullerene radical anion . The efficiency of photoinduced charge separation must be determined by the basic physicochemical properties of the ingredients of the polymer/fullerene composite. The process of photoinduced generation of radical pairs and their subsequent recombination in this system have not been studied yet.