New D-A-π-A Organic Dyes Containing Dithieno [3,2-b:2’,3’-d] Pyrrole Unit As Linker For Dye-sensitized Solar Cells

The dye of D-A-π-A is a structure that was introduced an electron-withdrawing groups(such as diazosulfide)as the electron acceptor in the basic D-π-A structure.Comparing with D-π-A structure,the structure of D-A-π-A can extend the absorption spectrum,improve the efficiency and ability of light-harvesting,adjust the HOMO and LUMO energy levels,reduce the forbidden bandwidth,as well as effectively improve the efficiency of energy conversion.So the D-A-π-A structure has a great value of research and development space.Dithieno[3,2-b:2’,3’-d]pyrrole(DTP)as a thiophene derivatives is a well π-bridge structure and easy to be modified,which can well improve the range of absorption spectra and the efficiency of electronic transmission,thus improve the efficiency of energy conversion.Based on mentioned as above,three new organic dyes of D-A-π-A have been synthesized with diazosulfide,thiophene,p-nitrophenol etc as the raw materials.The application of synthetic organic dyes in organic dye-sensitized solar cells,the influence of different π-bridge and the second electron donor group located in the π-bridge on the photoelectric properties,physical properties and photochemical properties of the type of D-A-π-A organic dye-sensitized solar cells has been examined,but also the photoelectric performance of the dyes in different electrolytes was studied.The results show that:(1)The π-conjugate bridge introduced in DTP group can more increase the ability of light-harvesting and broaden the range of absorption spectrum,but also reduce the dihedral angle of DTP,thus improve the efficiency of electron transfer;(2)FS16 and FS17 have a larger charge density and electronic life due to the introduction of the long alkyl chain which can more effectively inhibit electron recombination and molecular aggregation,thus improve the performance of the battery;(3)We found that the Co-phen electrolyte has the best effect in comparing with different electrolytes have an effect on the performance of the battery,and the energy conversion efficiency of the battery is reduced with the increase of the TBP concentration in the electrolyte,the best efficiency was obtained at 0.5 M;(4)FS17 has the best efficiency due to the ability of the second electron donor group is more stronger and the efficiency reached 8.14% at 0.5 M of the TBP concentration.