Synthesis And Characterization Of Side Chain Polymer Photovoltaic Materials Containning Malononitrile

In recent years,solar energy has received extensive attention as a clean and recyclable new energy source,and solar cells have been rapidly developed as promising photovoltaic technologies.Among the various photovoltaic materials,polymers have become the superior materials due to their outstanding advantages such as light weight,low cost and easy processing.Generally,the molecular design concept based on the D-A type and A-D-A type can easily regulate the energy bandgaps,charge mobility,absorption spectrum and morphology of the polymer.Therefore,we designed and synthesized the side-chain polymer donor materials based on D-A type and A-D-A type with a novel mesogen-jacketed structure in this paper.Among these polymers,the malononitrile is used as an electron withdrawing group,the alkylthiophene is regarded as electron-donating group,and the photovoltaic properties are preliminarily explored.1?We design and synthesize a series of monomers based on D-A type with different alkyl chain lengths,thiophene is regarded as electron donating group and malononitrile as electron withdrawing group.A series of corresponding polymers of P-T-C6?P-T-C8 and P-T-C10 are obtained by traditional free radical polymerization.The chemical structures of the monomers and polymers are confirmed by ¹HNMR,MALDI-TOF and FTIR.The thermal stability is studied by TGA,and we find that the polymers show good thermal stability.The photophysical properties and electrochemical properties of different alkyl chain length polymers are investigated by UV-vis and CV.The experimental results show that the absorption of the polymers in the film state gradually shift blue and the optical band gaps of the polymers gradually increase as the alkyl chain lengthens.At the same time,the polymers possess suitable spectral absorption and band gap,which can be used as good donor materials in photovoltaic devices.2?We design and synthesize a series of mesogen-jacketed side-chain polymer donor materials based on A-D-A types with different alkyl chain lengths:P-TT-Cm?m=6,8,10,12?.In the A-D-A type side chain,the trithiophene is used as an electron donating group and malononitrile as an electron withdrawing group.The structure of the monomers and polymers are identified by ¹HNMR,MALDI-TOF and FTIR.The study of thermal stability shows that the 5%weight loss temperature of the polymer exceeded 360°C indicating that the polymers have good thermal stability.The UV-vis and CV research results show that the polymers have a broad UV absorption(?_edge=620 nm)and a moderate electrochemical band gap?1.9eV?,the absorption of the polymer gradually shift blue and electrochemical band gap is broadened as the alkyl chain grows.And we also find the polymers P-TT-Cm based on the type of A-D-A possess wider spectral absorption,narrower optical gaps and higher power conversion efficiencies when used as donor materials in photovoltaic devices than that of D-A side chain polymers P-T-Cm.