Design Of Organic Dye Sensitizers With Double Electron Donors:The First Principle And Dynamics Study

The efficiency of the dye-sensitized solar cells decides this cells'wide application in the world,meanwhile,organic dyes are the most important components.Therefore,the design of new molecules is an important way to enhance the efficiency of dye-sensitized solar cells.Double donors organic dyes have been extensively studied due to their high oscillator strength and broader absorption spectrum.In our work,based on the highly efficient experiment dyes which have the structure of double donors type,we designed a series of novel organic dyes.The physical and electronic properties were further investigated by using density functional theory?DFT?and time-dependent density functional theory?TDDFT?,including geometry,molecular frontier orbital,absorption spectra and light harvesting efficiency?LHE?.For screening more promising dye molecules,we further carried out dynamics study dyes adsorbed to TiO₂ substrate.The main content of this paper is as follows:?1?Based on the experimentally synthesized WD8 organic dye with an efficiency of 6.79%,a series of novel dyes ME301-ME306 were designed by modifying the double donor and?bridge.We calculated their molecular structures,molecular frontier orbitals and UV-Vis absorption spectra,the absorption spectrum of ME306 redshifts50nm and the molar extinction coefficient is increased 2 times comparing to WD8.?2?To screen highly efficient double electron donors type organic dyes,a series dyes of dyes ME07-ME13 were obtained by modifying the electron donating groups.The results show that all designed dyes cover the entire visible absorption spectrum from 300-800 nm.It is fascinating that ME13 molecule has two absorption peaks and the molar coefficient of two absorption peaks are above 4.645×10⁴ M^-1·cm^-1.The light absorption area of ME13 exhibits an increment of 16.5-19.1%compared to ME07-ME12.The adsorption energy indicates that the dye ME13 can strongly be adsorbed on?TiO₂?₃₈ clusters.?3?By introducing auxiliary donor groups,double electron donors type dyes ME101-ME106 were designed.The organic dyes WD8 and ME101-ME106 were adsorbed on the TiO₂ substrate,the light-trapping efficiency,density of state,vertical excitation energy and absorption spectrum were calculated theoretically.The results revealed that,compared to WD8,absorption spectrum overall red shift,the molar extinction coefficient increases significantly,and the ultrafast electron are injected,which also suggest dyes ME102 and ME106 may be potentially highly efficient dye molecules.