In terms of material properties, the copolymers were obtained as yellow semi-solids, due to the presence of the C=S chromophore, that are soluble in common organic solvents such as THF, benzene or CHCl3. They show glass transition temperatures (Tg) ranging from -14 to +4°C (ESI Figure ) and show an onset of decomposition temperature (Td,5%) at ca. 160 °C (ESI Figure ). Hence the materials can be pressed into optically clear films with good refractive indices of RI = 1.48 to 1.61 due to the high sulfur contents in the polymer repeat units.