(Alkylsulfanyl)bithiophene-alt-Fluorene: π-Conjugated Polymers for Organic Solar Cells

• Published in: European Journal of Organic Chemistry Vol. 2011; no. 28; pp. 5659 - 5667
• Main Authors: Parenti, Francesca, Morvillo, Pasquale, Bobeico, Eugenia, Diana, Rosita, Lanzi, Massimiliano, Fontanesi, Claudio, Tassinari, Francesco, Schenetti, Luisa, Mucci, Adele
• Format: Book Review Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.10.2011; WILEY‐VCH Verlag; Wiley; Wiley-VCH
• Subjects: Applied sciences; C-C coupling; Chemistry; Chemistry, Organic; Condensed benzenic and aromatic compounds; Energy; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; Natural energy; Organic chemistry; Organic solar cells; Photovoltaic conversion; Physical Sciences; Polymers; Polythiophenes; Preparations and properties; Renewable resources; Science & Technology; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Thin films; Solar cells; C-C coupling; Thin films; Polythiophenes; PHOTOVOLTAIC CELLS; DESIGN; FLUORENE-BASED COPOLYMERS; Organic solar cells; Polymers; THIOPHENE; Renewable resources; ACCEPTOR; Chemical coupling; Thin film; Solar cell; Thiophene derivatives; Conjugated polymer; Sulfur heterocycle; Aromatic compound; Thiophene polymer; Fluorene derivatives
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201100738

We describe the synthesis of alternating bithiophene–fluorene copolymers (P1–P3) with different regiochemistry of the bithienyl unit and different alkylsulfanyl chain lengths. The structural, electrochemical and photophysical properties of these polymers were investigated by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), NMR, UV/Vis and photoluminescence (PL) spectroscopy and cyclic voltammetry (CV), and the polymers were used to assemble organic solar cells (OSCs), in combination with the fullerene derivative methyl [6,6]‐phenyl‐C61‐butyrate (PCBM). P3, with a head‐to‐head bithienyl unit, shows a broader absorption and a lower band gap with respect to P1 and P2, which have tail‐to‐tail bithienyl units. The PL intensity of P1–P3 is dramatically quenched in the presence of PCBM, demonstrating that an efficient charge transfer between donor and acceptor occurs. The best OSC device was obtained with P3. Alternating bithiophene–fluorene copolymers (P1–P3) with different regiochemistry of the bithienyl unit and different alkylsulfanyl chain lengths were synthesized and characterized (GPC, NMR, UV/Vis and PL spectroscopy and CV). These materials were used to assemble organic solar cells in combination with the fullerene derivative [6,6]‐phenyl‐C61‐methylbutyrate.