Low band gap polymers for application in solar cells: synthesis and characterization of thienothiophene–thiophene copolymers

• DOI: 10.1039/c3py01618h
• Publication Date: 2013-12-11T12:30:19Z
• Authors: P. Morvillo; R. Diana; C. Fontanesi; R. Ricciardi; M. Lanzi; A. Mucci; F. Tassinari; L. Schenetti; C. Minarini; F. Parenti
• Keywords: Thermogravimetric analysis; Gel permeation chromatography; Thermal Stability

In this paper we present the synthesis and characterization of two novel copolymers obtained from a bithiophene unit carrying octylsulfanyl side chains thienothiophene units substituted with keto (PK) or ester (PE) groups. Their structural, electrochemical photophysical properties were investigated by gel permeation chromatography (GPC), thermogravimetric analysis (TGA), NMR, UV-visible-NIR spectroscopy, cyclic voltammetry (CV) atomic force microscopy (AFM). They possess good solubility in common organic solvents, filmability, proneness to form π-stacks, moderate solvatochromism, thermal stability low band gap energy. tested as donor materials combination [70]PCBM (electron acceptor) bulk-heterojunction polymer solar cells. The geometry devices is: glass/ITO/PEDOT:PSS/copolymer:[70]PCBM/Ca/Al. external quantum efficiency curve best device, realized using blend PK : [70]PCBM, 1 2 weight ratio, shows broad response 350 1000 nm. power conversion under 100 mW cm−2 AM 1.5G illumination is greater than 1%.