Two-Dimensional Polyfluorenes Bearing Thienylenevinylene π-Bridge-Acceptor Side Chains for Photovoltaic Solar Cells

Abstract

Two-dimensional polyfluorenes bearing thienylenevinylene-bridged malononitrile ( PF-BTDCN ) or diethylthiobarbituric acid accepting side chains ( PF-BTDTA ) have been successfully prepared. The polymers were fully characterized for their physicochemical, electrochemical, and photovoltaic properties. These polymers exhibited greatly changed properties with the introduction of π-conjugated accepting side chains. The enhancement of current density for the bulk-heterojunction solar cells was observed when replacing the PEDOT:PSS interfacial layer with molybdenum oxide (MoO 3 ). Photovoltaic solar cells with the configuration ITO/MoO 3 /polymer:PCBM/Al exhibited an efficiency of 3.13% and 1.72% for PF-BTDCN and PF-BTDTA, respectively. A morphology study revealed the existence of nanoscale phase separation with interpenetration networks between polymer and PCBM domains.