Polythiophenes with Carbazole Side Chains: Design, Synthesis and Their Application in Organic Solar Cells

Abstract

AbstractA series of polythiophene derivatives P1‐P5 containing carbazole side chains were designed and synthesized via the Stille polymerization. All carbazole containing polymers showed broad absorption in the visible region. The power conversion efficiencies of solar cells based on blends of two component copolymers and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) were determined to be 0.29 and 0.56% for P1 and P5, respectively. For solar cells fabricated with the three component copolymers and PC61BM, the efficiencies were 0.56% for P2, 0.86% for P3, and 0.70% for P4. The introduction of electron‐donating carbazole side chains can broaden the absorption in the visible region and meanwhile reduce phase separation due to the steric hinderance of the carbazole moiety to the conjugated main chain. Improving efficiency needs a balance of broad absorption and ordered packing of polymer chains in the solid state.magnified image