A fluorine-functionalized alternating polymer with benzo[1,2-b:4,5-b′]dithiophene and quinoxaline segments for photovoltaic devices

A new alternating polymer (PBDTFQx) with alkoxy-substituted benzo[1,2-b:4,5-b′]dithiophene (BDT) as donor and fluorine-functionalized quinoxaline derivative (FQx) as acceptor, was synthesized and characterized using NMR, UV–vis spectroscopy, thermogravimetric analyses (TGA), and cyclic voltammetry. Photovoltaic devices with the configuration of ITO/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS)/PBDTFQx: [6,6]-phenyl C61-butyric acid methyl ester (PC61BM)/LiF/Al were fabricated, in which PBDTFQx performed as the electron donor and PC61BM as the electron acceptor. When the optimized weight ratio of PBDTFQx:PC61BM reached 1:2, the photovoltaic device exhibited acceptable performance with the open-circuit voltage (Voc), the short-circuit current density (Jsc), the fill factor (FF), and the power conversion efficiency (PCE) of 0.77 V, 2.46 mA/cm2, 0.54% and 1.02%, respectively. The experimental data implied that PBDTFQx would be a promising donor candidate in the application of polymer solar cells.