Theoretical Study On The Construction Of High-efficiency Sensitized Dye Molecules Based On Thiazole Unit

With the consumption of traditional fossil energy and the increasing seriousness of environmental problems,the search for clean and efficient new energy has become one of the goals of today’s technological development.Solar energy is considered to be one of the perfect green new energy because of its endless and pollution-free characteristics.As a third-generation solar cell,sensitized solar cells have attracted attention from the industry due to their low cost and simple manufacturing process.Dye-sensitized solar cells（DSSCs）have become a hot spot,in which sensitizers as absorbers of light and excitation states in batteries have become one of the most important components of DSSCs,and by optimizing their structure,they have become a research hotspot in academia to find the structure-activity relationship that controls and affects the photoelectric conversion efficiency.Based on the traditional D-π-A type organic dye,this thesis calculates and simulates it by designing,expanding the structure and using theoretical methods such as density functionals,and comparing it with relevant experimental data,quantitatively calculating the photoelectric parameters and clarifying the relationship between its structure and properties,and studying the photoelectric properties of a series of designed dye sensitizers from a microscopic perspective in different aspects such as molecular structure,front-line molecular orbitals,absorption spectroscopy,electron transfer,etc.Firstly,the effects of different donors and ligation methods on the performance of dye molecules were studied.Based on the traditional D-π-A structure,benzothiazole was introduced asπ-bridge,cyanoacrylic acid was used as acceptor,triphenylamine,carbazole,phenothiazine were used as donors,and its connection mode was changed,and the DFT method was used to selectωb97xd/6-31G（d,p）through functional verification,and the study found that the introduction of benzothiazole reduced steric hindrance,effectively improved the size of the torsion angle,and increased the coplanarity of the dye molecule.The change of connection mode also has a great impact on the planarity of molecules;The designed dyes meet the HOMO orbital energy level is lower than the redox potential of I^-/I₃^-（-4.8e V）,and the LUMO energy level is higher than the Ti O₂ conduction band energy level（-4.00e V）,which can ensure the efficient injection of electrons and dye regeneration;the electron cloud distribution of the front-line molecular orbital also presents a clear charge separation state,which can realize electron transfer;it has maximum light absorption in the range of383nm～423nm,and has good light capture ability.Subsequently,the effect of the introduction of co-receptors on the molecular structure of the dye was studied,and the effect of different additional receptors on the performance of the dye was studied.With the support of the D-π-A structure,carbazole with strong power supply capacity was selected as the donor,thiophene with good planarity was selected asπ-bridge,cyanoacrylic acid was used as the anchor group,and benzothiadiazole,pyridinethiadiazole,naphthiothiadiazole,benzobishiadiazole,dithiol benzothiadiazole,malononitrile,naphthiodithiadiazole,benzotrithiadiazole and other thiazole molecules were introduced as additional acceptors,inωb97xd/6-31G（d,p）Calculations are carried out at the functional level,and the molecular structure has good flatness from a macroscopic point of view.It has suitable HOMO and LUMO orbitals,and the energy level difference is reduced,and it has good electron transition ability;The maximum absorption peak of the designed dye absorption spectrum is 403.53nm～688.39nm,indicating that the co-acceptor has a great influence on the light absorption range and greatly improves the light capture ability;the binding of the dye sensitizer to Ti O₂ is simulated to realize the injection of electrons from dye to semiconductor.Finally,the effect of triphenylamine binding to additional thiazole receptors on the performance of dye sensitizers was studied.On the basis of the previous chapter,the carbazole group was replaced with triphenylamine,which has good electron giving ability and hole transport performance,and explored the performance of thiazole dyes under triphenylamine donors.Similarly,ωb97xd/6-31G（d,p）functionals are selected for calculation,which increases the planarity of the acceptor group well from the molecular structure point of view,which is beneficial to charge transfer;Appropriate HOMO and LUMO energy levels make the energy gap of dye molecules smaller,realize the redshift of absorption spectrum,and show a clear charge separation state in the electron cloud distribution,so that electrons have sufficient driving force to inject into the Ti O₂ conduction band.Through the calculation of light capture efficiency,it is shown that the designed dye has good light capture performance.