The Electronic Structures And Properties Of Rhenium(Ⅰ) Tricarbonyl Complexes As Dye Sensitizer

In today’s deepening energy crisis,fossil energy is not renewable;at the same time,the use of hydrogen energy is also a certain problem;people also find it hard to exploit wind energy and nuclear energy in a wide range.Solar energy as another renewable resource,which is environment-friendly and safe,also has the better stability,higher conversion efficiency and lower cost,and so on.In recent years,dye sensitizer solar cell（DSSC）is attracting great interest from scientists.But so far solar-to-electricity conversion efficiency of DSSC is low,and the dye-sensitizer plays an important role in the solar-to-electricity conversion.Therefore,the design of effcient dye sensitizer is keys to improve the conversion efficiencyof DSSC.At present,containing ruthenium complexes（Ⅱ）dye sensitizer research widely,for rhenium（Ⅰ）complexes of research is less.In addition,Re（Ⅰ）complexes also have widely attracted owing to their long-term stability of chemistry and photochemistry properties,relatively long-lived excited states,higher oxidation-reduction potentials and strong absorption,and so on.So,the researches of rhenium complexes are conductive to improve performance of the new dye sensitizer.The main works are designing and developing a dye sensitizer for the tricarbonyl rhenium（Ⅰ）complex by changing the ligand structure.In the work,adopting several quantum chemistry methods,considering the solven effects,we are in–depth study the ground-and excited-state spectroscopic properties of the complexes in dichloromethan,and the effects of dye sensitizer on the related parameters about efficiency of DSSC are also study.So that,we can explain the nature relation between the geometric structure and photoelectric properties to achieve the purpose of predicting new sensitized material performance.The specific research details are as follows:（1）By changing the substitutive group numbers or and positions of COOH group on the ligand moiety of the photoelectric performance of Re（CO）₃Cl L（L=5-[{2-[4,5-Bis（methylthio）-1,3-dithiol-2-ylidene]-5-（methylthio）-1,3-dithiol-4-yl}hio]-methyl-2,2’-bipyridine;a）,Re（CO）₃Cl（Hnnapy TTF）（napy=naphthyridine;TTF=Tetrathiafulvalene;b）have been researched theoretically by DFT and TDDFT.The results show that the different numbers and positions of carboxyl group can greatly change the frontier molecular orbital,especially,LUMO,which can change the light-absorbing and electronic transport ability of dye sensitizer and efficiency of DSSC.The new designed a3 and a6 、 b2 and b5 complexes are conductive to improve efficient of the DSSC.（2）By changing the substitutive group on the X moiety,we detailedly studied the photoelectric performance of Re（CO）₃X（L）（L represent that the different molecular bridges between bipyridine and carboxylicacid anchoring groups,such as,ethylene,thiophene and so on）.The results show that the X ligand with a stronger π-donating ability can obviously decrease the energy levels,narrowing the energy gap between HOMO-LUMO,especially,1-3.To be more important,the absorption energy increase in the order–CN（1）<-Cl（3）<-C o CH（2）is in agreement that of the increasing π-donating ability of X ligands,and 2 complex is obvioue red-shift and more favorable to the process of electron injection and improve the efficient in DSSC.