Furan-Based Narrow-Band-Gap Copolymers for Red Light-Emitting Diodes and Bulk Heterojunction Photovoltaic Cells

Abstract

A series of conjugated copolymers (PFO-DFQ) derived from 2,3-dimethyl-5,8-difuran-2-yl-quinoxalines (DFQ) and 9,9-dioctylfluorene (DOF) were prepared by the palladium-catalyzed Suzuki coupling reaction with molar feed ratios of DFQ around 1%, 5%, 15% 30% and 50% respectively. The obtained polymers were readily soluble in common organic solvents. The absorption spectra of the copolymers ranged from 300 nm to 560 nm, with two absorption peaks at around 390 nm and 480 nm, both in solution and thin film. The photoluminescence (PL) emission peaks were in the region from 465 nm to 611 nm in thin solid films. The electroluminescence (EL) emission peaks were from 550 nm to 712 nm, depending on the DFQ content. Bulk heterojunction photovoltaic cells fabricated from composite films of PFO-DFQ copolymers and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as electron donor and electron acceptor respectively, showed power conversion efficiencies 0.13% with open-circuit voltage (Voc) of 0.60V and short-circuit current density (Jsc) of 0.68 mA/cm2 under AM1.5 solar simulator (100 mW/cm2).