PTV-based p-type organic semiconductors: Candidates for low-cost photovoltaic donors with simple synthetic routes

Organic photovoltaic (OPV) technique aims to realize roll-to-roll printing of semi-transparent, mechanically flexible and low-cost photovoltaic devices. The reported power conversion efficiencies (PCEs), based on high performance light-harvesting materials, have been close to the requirement of practical application. However, scaling up and processability of the materials have become one of the main barriers inhibiting the OPV commercialization. In order to provide ideas for solving the cost issue, a series of low-cost p-type copolymers, PTV-X (X represents different alkyl side chains) with copolymerization of thienylene and vinylene as backbones, are prepared and characterized. It was demonstrated that PTV-based materials possess almost flat structure and broad absorption spectra range from 300 to 750 nm. Besides, the hole mobilities of the optimized materials are up to magnitude of 10(-4) cm(2) V-1 s(-1). Importantly, the PTV-X family polymers can work effectively with various representative fullerene and non-fullerene acceptors. A regioregular polymer, namely PTVT-C12, is synthesized based on monomers of (thiophene-vinylene-thiophene) TVT-C12 and V-Sn to further modulate the morphological properties of the PTV-series polymers. The more ordered chain packing was observed in PTVT-C12 film and enhanced charge carrier mobility was realized in PTVT-C12 based OSC device. As a result, a PCE of 6.44% is exhibited by the device based on PTVT-C12: BO-4Cl. This study suggests that PTV-series materials are being worthy of consideration for the development of low-cost materials for the future OPV commercialization.