Synthesis And Characterization Of Mesogen-Jacketed Liquid Crystalline Polymers And Small Molecular Photovoltaic Materials Containing A-D-A Structure

Based on the chemical structure of mesogen-jacketed liquid crystalline polymers,a series of mesogen-jacketed liquid crystalline polymers with A-D-A type and different alkyl tail chain were designed and synthesized in this paper.In the A-D-A type liquid crystal unit,D isthe triple thiophene electron donor group and A is the carboxylate electron acceptor group.The effects of liquid crystal behavior and the tail chain length on liquid crystal properties were studied.In addition,we have designed and synthesized small molecular photovoltaic materials S-TT and S-TT-R containing A-D-A structure,the D is the triple thiophene electron donor group and A is the rhodanine electron acceptor group.The optoelectronic properties of the A-D-A type S-TT and S-TT-R photovoltaic materials with or without alkyl chains introduced on the thiophene ring are preliminarily explored.1?A series of A-D-A type mesogen-jacketed liquid crystalline polymers with different alkyl tail chains based on the triple thiophene as electron donor group and the carboxylate electron as acceptor group have been designed and synthesized.A series of polymers(poly { 2,4-di(4'-alkoxycarbonylthienyl)thiophene ethylene }P-TT-Cn,n is the length of the alkyl chain tail chain,n = 4,6,8)are obtained by ordinary free radical polymerization.The experimental results show that a series of polymers have narrow molecular weight distribution n stable liquid crystal phase and the glass transition temperature decreases with the increase of tail chain length of alkyl group.When polymers enter the liquid crystal phase at a certain temperature,the phase structure is columnar,the liquid crystal phase can be stably present at a high temperature and still exists even cooled to room temperature.In addition,this kind of polymer has good thermal stability and solubility with no bright spots.It is a typical mesogen-jacketed liquid crystalline polymers.2.We have designed and synthesized small molecular photovoltaic materials S-TT and S-TT-R containing A-D-A structure,the D is the triple thiophene electron donor group and A is the rhodanine electron acceptor group.The effect of the introduction or non-incorporation of alkyl chains on thiophene on the photophysical properties,electrochemical properties and molecular aggregation of the small molecules have been investigated.The experimental results show that small molecule S-TT-R with alkyl chain on thiophene ring has better solubility and more orderly molecular stacking than small molecule S-TT without alkyl chain,so its OSCs exhibit a higher PCE value of 0.45%with open-circuit voltage(Voc)of 0.68 V,short-circuit current density(Jsc)of 1.25 mA cm-2 and a fill factor(FF)of 52.32%.