Synthesis and photovoltaic properties of two-dimensional conjugated polythiophene derivatives presenting conjugated triphenylamine/thiophene moieties

• Published in: Polymer (Guilford) Vol. 53; no. 19; pp. 4091 - 4103
• Main Authors: Wang, Hsing-Ju, Chen, Yuan-Peng, Chen, Yung-Chung, Chen, Chih-Ping, Lee, Rong-Ho, Chan, Li-Hsin, Jeng, Ru-Jong
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 31.08.2012; Elsevier
• Subjects: absorption; Applied sciences; electric power; Energy; Exact sciences and technology; fullerene; Natural energy; Organic polymers; photovoltaic cells; Photovoltaic conversion; Photovoltaic property; Physicochemistry of polymers; Polymer solar cell; polymers; Polymers with particular properties; Polythiophene derivatives; Preparation, kinetics, thermodynamics, mechanism and catalysts; Solar cells. Photoelectrochemical cells; Solar energy; thiophene; wavelengths; Photovoltaic property; Polymer solar cell; Polythiophene derivatives; Stille coupling; Short circuit currents; Fullerene compounds; Solution polycondensation; Photoluminescence; Organic solar cells; Experimental study; Fill factor; Functional polymer; Open circuit voltage; Suzuki coupling; Electrochemical properties; Conjugated copolymer; Optical properties; Morphology; Preparation; Phenylene copolymer; Thiophene derivative copolymer; Phenylenevinylene copolymer; Optical absorption; Amine copolymer
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2012.07.010

In this study we synthesized three two-dimensional (2-D) polythiophene derivatives (PTs), namely PTBPTPA, PTStTPA, and PTCNStTPA, featuring three different conjugated units—biphenyl (BP), stilbene (St), and cyanostilbene (CNSt), respectively—in the polymer backbones and presenting conjugated triphenylamine/thiophene (TPATh) moieties on the side chains. In addition, we also synthesized three conjugated BP-, St-, and CNSt-based main-chain-type conjugated polymers (PTBP, PTSt, and PTCNSt, respectively). Incorporating the St and CNSt moieties into the polymer backbones and appending TPATh units induced high degrees of intramolecular charge transfer within the conjugated frameworks of the polymers, thereby resulting in lower band gap energies and red-shifting of the maximal UV–Vis absorption wavelengths. Moreover, the energy levels of the highest occupied molecular orbitals of the BP-, St-, and CNSt-based main-chain-type and 2-D PTs were lower than that of P3HT, implying that they would be applicable for the preparation of polymer solar cells (PSC) with greater open-circuit voltages. The photovoltaic performances of PSCs fabricated from blends of the 2-D PTs and the fullerene derivative PC61BM were superior to those of PSCs based on the main-chain-type polymer/PC61BM blends. [Display omitted]