An isoindigo and dithieno[3,2-b:2′,3′-d]silole copolymer for polymer solar cells

The copolymer of isoindigo and dithieno[3,2-b:2′,3′-d]silole, P(iI-DTS), is reported as prepared by Stille coupling to yield a soluble high molecular weight material absorbing light throughout the visible spectrum up to 800 nm. With deep HOMO and LUMO energy levels (high ionization potential and electron affinity) electrochemically measured at −5.55 and −3.95 eV respectively, this new p-type polymer enabled the fabrication of high open circuit voltage polymer solar cells when blended with fullerene derivatives. By employing solvent additives, the morphology of the devices was optimized to yield power conversion efficiencies of 4%.