Synthesis and characterization of conjugated copolymer containing 2,5-bis(3-decylthiophen-2-yl)thiazolo[5,4-d]thiazole and 2,6-[(1,5-didecyloxy)naphthalene for polymer solar cells

• Published in: Synthetic metals 2011-08, Vol.161 (15), p.1582-1589
• Main Authors: Dutta, Pranabesh, Yang, Wooseung, Park, Hanok, Baek, Myung-jin, Lee, Youn-Sik, Lee, Soo-Hyoung
• Format: Article
• Language: English
• Subjects: Applied sciences; Bulk-heterojunction polymer solar cell; Copolymers; Density; Devices; Donor–acceptor conjugated polymer; Energy; Exact sciences and technology; Indium tin oxide; Natural energy; Organic polymers; Photovoltaic cells; Photovoltaic conversion; Physicochemistry of polymers; Polymerization; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Thermal properties; Thiazolothaizole
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2011.05.022

► Conjugated copolymer based on thiazolothiazole and didecyloxynaphthalene units was synthesized. ► Photovoltaic properties of the copolymer were investigated blended with electron acceptor, PC 61BM. ► The optimized photovoltaic device shows a power conversion efficiency up to 0.99%. A new alternating donor–acceptor conjugated copolymer, poly{(2,5-bis(3-decylthiophen-2-yl)thiazolo[5,4-d]thiazole-5,5′-diyl)- alt-(2,6-[(1,5-didecyloxy)naphthalene])} (PNTzTz) based on thiazolothiazole and didecyloxynaphthalene units was synthesized using a typical Suzuki coupling polymerization method and was explored as a donor polymer in bulk heterojunction (BHJ) solar cells. The copolymer was characterized using differential scanning calorimetry, thermogravimetric analysis, UV–Vis absorption and cyclic voltammetry. It possesses moderate molecular weights and excellent thermal properties with a 5% weight loss around 340 °C. It also exhibits good optical absorption with an absorption peak at 475 nm and an absorption onset at 560 nm in the film state. Photovoltaic properties of the copolymer were investigated blended with electron acceptor, [6,6]-phenyl-C 61-butyric acid methyl ester (PC 61BM). The optimized photovoltaic device with a device structure of ITO/PEDOT:PSS/PNTzTz:PC 61BM (1:2, w/w)/LiF/Al shows a power conversion efficiency up to 0.99% with a short circuit current density of 3.3 mA cm −2, an open circuit voltage of 0.96 V and a fill factor of 0.33 under the illumination of AM 1.5, 100 mW cm −2.