Two novel propylenedioxythiophene-based copolymers with donor-acceptor structures for organic solar cell materials

Two novel conjugated copolymers consisting of alternating electron-rich propylenedioxythiophene and electron-deficient 2,3-diphenyltheno[3,4-b]pyrazine or 6,7-diphenyl[1,2,5]thiadiazole units have been synthesized through palladium catalyzed Sonogashira triple-bond coupling reaction. The structures and properties of the two copolymers, P (1) , P (2) , were characterized by FT-IR, NMR, UV-Vis absorbance (Abs), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and cyclic voltammetry (CV). UV-Vis absorption spectra of the polymers show two absorption bands both in CHCl3 solution and films. The absorption peak maxima of P (1) , P (2) are 600 nm, 766 nm in solution and 627 nm, 823 nm in films, respectively. Thermal gravimetric analysis demonstrates that the two polymers are stable below 300 A degrees C. Cyclic voltammetry studies reveal that the band gaps of P (1) , P (2) are 1.62 eV and 1.50 eV, suggesting their potential for applications as organic solar cell materials.