Role of Si/film interface in photovoltaic devices based on aromatic molecular films

Sandwich structures based on cast films of poly(3-dodecylthiophene) (PDDT) and multilayer Langmuir–Blodgett (LB) corbathiene films are studied under ambient conditions. The two types of the structures demonstrate similar photovoltaic properties. Photovoltage and photoconductivity are particularly distinguishable when n-Si substrate is used in the structures. Two photovoltaic components are observed: caused by light absorption in the film and caused by light absorption in n-Si substrate. Donor–acceptor interaction at film/n-Si interface superposed on rigid-band approach is used to suggest mechanisms of the phenomena observed. The mechanisms may be used in order to provide a low work function electrode for organic light emitting diodes.