Bulk Heterojunction Organic Photovoltaic Cell Fabricated with a p-Type Conjugated Star-shaped Molecule

Abstract

Abstract A new multibranched crystalline molecule was synthesized through Horner–Emmons reactions using hexyl-substituted thiophene-based carbaldehydes as dendrons and benzene-1,2,4,5-tetramethylphosphonic acid octaethyl ester as the core unit. The molecule was employed to fabricate organic photovoltaic (OPV) cells with methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM). Poly(3-hexylthiophene) (P3HT) was also used as a dopant to improve the film quality and power conversion efficiency. As a result, the short-circuit current density and open circuit voltage were increased when P3HT was added into 4(HPBT) and PCBM dyad, resulting in a higher power conversion efficiency of around 0.6%.