Molecular Engineering Of Phenothiazine Double-stranded Dye Based On Rigid Bridge

Because of its huge energy,solar energy has been paid attention to by researchers.However,since the development of solar energy,the conversion rate of solar energy has yet to be improved.Therefore,the most efficient use of inexhaustible solar energy has become one of the ideal strategies to solve the energy crisis.In the process of developing solar energy,scientis ts took inspiration from photosynthesis of plants and designed a new type of solar cel,dye-sensitized solar cel s(DSSC).With the advantages of easy preparation,low cost,and diverse structures,pure organic compounds have gradually replaced precious metal complexes as photosensitizers in DSSC.Its main role is to absorb sunlight and inject free-moving electrons into the titanium dioxide conduction band,and at the same time quickly replenish electrons from the electrolyte solution to complete regeneration.It can be found that organic dye photosensitizers are very important components in dye-sensitized solar cell systems.In this thesis,four pure organic dye sensitizers with phenothiazine as the electron donor and cyanoacrylic acid as the electron acceptor,and supplemented with fluorene units to increase the charge of the dye,are respectively FSDD-1 and FSDD-2.,FSSD-E,FSSD-EH.Among them,FSSD series are typical single-stranded D-?-A structure dyes,and FSDD series are new type double-stranded(D-?-A)₂structure dyes.A series of compounds were characterized by nuclear magnetic resonance,mass spectrometry,and other methods The photophysical,thermal stability and electrochemical properties of the dyes were fabricated into simple solar cel s.The influence of the structure of organic dyes on the overall performance of DSSC was investiga ted.The structure of organic dye sensitizers is closely related to all aspects of its performance.By extending the alkyl chain of the dye,the aggregation effect of the dye molecules on the Ti O 2conduction band is reduced.At the same time,the fluorene unit is introduced to enhance the electron donor ability and fluorescence performance of the dye molecule.Single-chain dyes form a double-chain(D-?-A)₂structure,which widens the conjugate system of the dye and enhances the light absorption and light-capture capabilities of the dye.It was also found that wider bridging units can also reduce the accumulation of dyes on the conduction band.The HOMO-LUMO energy levels of the four dyes all meet the requirements of dye electron injection and reduction regeneration.Organic sensitizers synthesized with phenothiazine as the electron-donating group all showed good battery performance.Studies have shown that compared with single-chain dyes,the open-circuit voltage and short-circuit current density of double-chain dyes all exhibit the advantages of roller compaction grade,and the wider conjugate structure can also improve the photoelectric conversion efficiency of DSSC.After continuous optimization and test comparison,the double-stranded double-alkyne bridge dye FSDD-2 sensitized solar cell has obtained the best battery performance.Under simulated sunlight(AM1.5,100m W/cm2),the open-circuit voltage is 0.74V.The short-circuit current density is 9.6 m A/cm²,the fill factor is0.79,and the total photoelectric efficiency can reach 5.6%.Its efficiency is 188%of the single-chain dye FSDD-EH dye-sensitized battery,and 130%of the double-chain single-alkyne bond bridge dye-sensitized battery.