Thienylene-dialkoxyphenylene copolymers with polar side chains are soluble in most organic solvents and exhibit excellent glass adhesion properties, allowing the formation of homogeneous thin films on glass, quartz, and other substrates by spin coating. The electrochemical and optical properties of thin films of this material are studied in this work. The calculated band gap derived from electrochemical data (2.34 eV) is in good agreement with that observed from the UV-vis spectrum edge (2.25 eV). The analysis of the emission properties reveals the strong dependence on temperature of the electron coupling with different vibrational modes in the formation of the vibronic bands. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 964-971, 2010