In the past few years, ternary polymer solar cells(PSCs) have emerged as a promising structure to simultaneously improve all solar cell parameters compared with traditional binary PSCs. The third component in ternary PSCs can play versatile functions to enhance the device performance.In this review, we summarize the design rules for fabricating high-performance ternary PSCs and introduce the recent progress in this field. In addition, the characterization methods for determining the role of the third component played in ternary PSCs are described.
6,7-Dialkoxy-2,3-diphenylquinoxaline based narrow band gap conjugated polymers, poly[2,7-（9-octyl-9H- carbazole）-alt-5,5-（5,8-di-2-thinenyl-（6,7-dialkoxy-2,3-diphenylquinoxaline））] （PCDTQ） and poly[2,7-（9,9-dioctylfluorene）- alt-5,5-（5,8-di-2-thinenyl-（6,7-dialkoxy-2,3-diphenylquinoxaline））] （PFDTQ）, have been synthesized by Suzuki polycondensation. Their optical, electrochemical, transport and photovoltaic properties have been investigated in detail. Hole mobilities of PCDTQ and PFDTQ films spin coated from 1,2-dichlorobenzene （DCB） solutions are 1.0 X 10-4 and 4.1 X 10-4 cm2 V-1 s-l, respectively. Polymer solar cells were fabricated with the as-synthesized polymers as the donor and PC61BM and PC7 IBM as the acceptor. Devices based on PCDTQ：PC71BM （1：3） and PFDTQ：PC7 IBM （1：3） fabricated from DCB solutions demonstrated a power conversion efficiency （PCE） of 2.5% with a Voc of 0.95 V and a PCE of 2.5% with a Voof 0.98 V, respectively, indicating they are promising donor materials.
Two conjugated polymers HXS-1 and PDFCDTBT were prepared by direct C–H activation and Suzuki polycondensation and their chemical structures were characterized by 1H NMR spectroscopy.The molecular weight of conjugated polymer synthesized by direct C–H activation is lower than the corresponding polymers prepared by Suzuki polycondensation.Conjugated polymers synthesized by direct C–H activation have considerable solubility in common organic solvents and form amorphous film.The photovoltaic property of conjugated polymers synthesized by direct C–H activation is inferior to the corresponding polymers synthesized by Suzuki polycondensation.
