With copolymerization functionalization, a novel solution-processable polymer, polyl(3-octylthiophene)co-[3-(2-ethyl-1-hexyl)thiophenel] (P30TIOT), combining the electrochemical properties of poly(3-octylthiophene) (P30T) and pol3,[3-(2-ethyl-1-hexyl)thiophene] (P3IOT) was synthesized by the FeCl3-oxidative approach. The characterization of the polymers included Fourier transform infrared, H-1-NMR, gel permeation chromatography, thermogravimetric analysis (TGA), ultraviolet-visible spectroscopy, and photoluminescence (PL). P30TIOT had excellent solubility in common organic solvents. Investigations of the optical properties showed that the optical band-gap energy of P30TIOT was similar to that of P3OT (2.43 eV) at 2.45 eV and 6% lower than that of P3IOT in CHCl3 Solutions. The bandwidth of the P30TIOT absorption approached that of MOT, ranging from 370 to 570 rim, and the emission maximum of P30TIOT was only 50 nm blueshifted with respect to that of P30T. However, the PL intensity of P30TIOT was 7 times higher than that of P30T. TGA studies showed that P30TIOT had very good thermal stability, losing 5% of its weight on heating to 300 degrees C. It is suggested that P30TIOT has low band-gap energy, a high PL quantum yield, and processability. (c) 2007 Wiley Periodicals, Inc.