Theoretical Studies On The Performance Of Rhenium And Ruthenium Complexes As Dye Sensitizer

In recent years,with the earth’s environment problems are increasingly serious,the current situation of energy shortage becomes more obvious.Solar energy as a kind of clean environmental protection and natural resource,has become the first choice for human to deal with energy crisis.Dye-sensitised solar cell is a low-cost photoelectric device which can convert solar energy directly into electrical energy.What’s more,they get a lot of researchers’ attention for they become the most economic,effective and the most promising technology.In the past decades,a lot of researchers were committed to get good performance dye sensitized solar cell devices.However,the photoelectric conversion efficiency of dye sensitized solar cell is still lower than the silicon photocell,so how to improve its work efficiency is the key to the research work.Besides,dye sensitizing agent in the dye-sensitised solar cells plays an important role in absorbing sunlight,which can generate photoelectron and send them to the TiO2 conduction band and then can exist in the redox electrolyte solution for regeneration.Thus there are very close relationship between the performance of the dye sensitizer and the photoelectric conversion efficiency of DSSC.In this paper,on the basis of the experimental synthesis of rhenium(Ⅰ),ruthenium(Ⅱ)complexes,we use the quantum chemical calculation method to design a serious of new dye molecules and to reveal the different substituents,which affect the ground states,excited states,the frontier molecular orbitals and the absorption spectra of the molecules.By comparison,we can forecast the higher performance dye molecules.The main contents are as follows:1.The effect of the different number and positions of carboxyl group on pyridine ligand on electronic structure and spectral properties of eight Re(Ⅰ)tetracarbonyl complexes with tetrathiafulvalene-fused pyridine ligands Re(CO)4(HnL)(n=1,a1-a2;n=2,b1-b6;L=La-imine-2-pyridyl;La=2-(5,6-dihydro[1,3]dithiolo[4,5-b][1,4]dithiin-2-ylidene)-1,3-benzodithiol-5-am-ine have been carried out using density functional theory(DFT)and time-dependent density functional theory(TDDFT).The related parameters were calculated to evaluate the potentialapplied value of dye sensitizer in DSSC.The results show that the different number and positions of carboxyl group can affect the properties of the frontier molecular orbital,particularly,the LUMO.And then it can alter the light-absorbing and electronic transport capacity of dye sensitizer.The new designed dye sensitizers a1 and b6 may have better performance than other designed dyes.2.The present work designed and investigated the properties of ten tricarbonyl Re(Ⅰ)complexes with tetrathiafulvalene-substituted bispyrazol ligand.After COOH groups are anchored to pyrazol ligand,the electronic structure and optical properties have changed.Through the frontier molecular orbital,absorption spectrum data and other parameters analysis,complexes D1 and D5 have better photoelectric conversion efficiency,so they may be more likely to become the effective dye sensitized materials.3.The adding different electron-donating and electron-withdrawing groups on bispyrazol ligand effect on electronic structures and spectroscopic properties of a series of ruthenium(Ⅱ)complexes [Ru(Ⅱ)(bipy)(DABA)(NCS)2] as dyes in DSSC.The results show that the HOMO-LUMO energy gaps are obviously decrease,absorption capacity increase and absorption spectra have obvious red-shift along with the increasing of electron-withdrawing properties of functional groups.But it is opposite of the properties of electron-donating functional groups.We can come to the conclusion that 4 may be the higher performance dye sensitizer than other designed dyes.