Study On The Synthesis And Performance Of Dyes With Rhodanine-3-p-benzoic Acid As The Acceptor And Benzothiadiazole As The Co-acceptor

In the past,the energy we used was mainly fossil energy.On the one hand,the use of fossil energy has caused environmental pollution and the greenhouse effect On the other hand,with the growth of global economy and population,our demand for energy is also increasing.Therefore,solving the energy problem is very important to human life.Among all renewable energy sources,solar energy has attracted extensive attention of researchers because it is inexhaustible,clean and safe.Among photovoltaic solar cells,dye-sensitized solar cells have attracted the attention of researchers because of their low cost,flexible structure design and so on.As the most important part of DSSSs,dye sensitizer plays a role in capturing light energy and intramolecular charge transfer,which directly affects the performance of photovoltaic cells.1.In this paper,we designed and synthesized dye RA and reference dye CA with triphenylamine as the electron donors,and rhodanine-3-p-benzoic acid and cyanoacetic acid as electron acceptors respectively.Two dyes AS and AO with D-?-A'-A type were designed and synthesized.Thiourea functionalized triphenylamine was used as electron donor,thiophene and furan as ?-bridge chain,benzothiadiazole(BTH)as auxiliary acceptor and cyanoacetic acid as electron acceptor,and a dye AY with D-A-A type was designed and synthesized.Thiourea-functionalized triphenylamine was used as electron donor,benzothiadiazole(BTH)as auxiliary acceptor and cyanoacetic acetate as electron acceptor.The structures of intermediates and final products were characterized by NMR,MS and IR spectra.The dyes were studied by photophysical properties,electrochemical cyclic voltammetry,density functional theory(DFT)calculations and photovoltaic properties.2.Using p-aminobenzoic acid as raw material,dye RA and reference dye CA were synthesized by ring closure,Knoevenagel reaction and so on.The dyes AS,AO and AY were synthesized from 2,3-diaminotoluene by the reaction of chlorosulfoxide ring closure,liquid bromine bromine,NBS bromination,oxidation reaction,Suzuli coupling and Knoevenagel.By 1H NMR,MS and IR characterization of the structure of intermediates and final products.3.The photophysical properties of the dyes were tested.The UV-visible absorption showed that the maximum absorption wavelength of the dye RA was red-shifted by 48 nm compared with the reference dye CA,but the molar absorptivity was reduced by 8059 M-1 cm-1.Compared with the reference dye AZ6,the maximum absorption wavelengths of the dyes AS,AO and AY are red-shifted,and the maximum absorption wavelengths of AS and AO are almost the same.Compared with AY,the red shift is caused by the extension of the conjugated chain.However,the molar absorption coefficient is reduced,and the molar absorptivity may be related to the light capture ability of the dye.4.DFT calculates the electron cloud distribution of the dye molecules RA,AS,AO and AY and the dihedral angle.The dihedral angle between the rhodamine ring and the benzene ring in the dye RA is 76.90°.Because the dihedral angle of the dye molecule is too large,the ?-? conjugation in the molecule is destruction,which may be the main reason for the decrease of RA photovoltaic performance.Compared with AZ6,the dihedral angles of dyes AS,AO and AY are relatively small,almost close to the planar structure,which increased molecular aggregation and ?-? stacking.5.Electrochemical cyclic voltammetry tests show that the HOMO and LUMO levels of dyes RA,AS,AO and AY can meet the energy level requirements of dye sensitizers.6.The battery was tested for photovoltaic performance.Compared with CA,the open circuit voltage,short circuit current density and photoelectric conversion efficiency of dye RA were decreased.This may be the dihedral angle in the structure is too large,the ?-conjugated chain is destroyed,and the excited state electrons are blocked from the donor to the acceptor,resulting in a decrease in photovoltaic performance.Compared with AZ6,the dye AS,AO and AY photovoltaic performance data are relatively low,which may be its near-planar molecular structure,the ?-?stacking or agglomeration of dye molecules on the surface of Ti02 is too strong,resulting in electronic composite comparison serious.