Green Dioxythiophene-Benzothiadiazole Donor−Acceptor Copolymers for Photovoltaic Device Applications

With the perspective of producing power-generating displays of various colors based on π-conjugated semiconducting polymers, we have developed a synthetic design aimed at addressing color states commonly difficult to attain. Herein, we report on the structure−property relationships and performance in photovoltaic devices of a series of green-colored donor−acceptor (DA) π-conjugated polymers comprised of electron-rich 3,4-dioxythiophenes (DOTs) and the electron-deficient 2,1,3-benzothiadiazole (BTD). In particular, the synthesis and chemical polymerization of two DOT-BTD regiosymmetric oligomers (pentamers M2 and M3), that can be chemically oxidized to yield two-band absorbing polymers with a transmission window in the 480−560 nm range hence reflecting/transmitting the color green (P2 and P3), is reported. The optical and electrochemical properties of P2 and P3 are described and compared to those of a blue-colored parent polymer (P1) obtained via the polymerization of a smaller DOT-BTD oligomeric precursor...