Twisted Fused-ring Thiophene Organic Dye-sensitized Solar Cells

The burning of fossil fuels has generated huge environment pollution,and human is committed to the exploitation of solar energy.Dye-sensitized solar cells(DSSCs)have gained significant attention for their low cost,ease of fabrication and relatively high conversion efficiency.Therefore,our work is mainly related to the design of organic arylamine dyes and study of photovoltaic performance.Regulation the structure of the dyes by employing a side chain in arylamine donor can effectively adjust energy level,reduce the charge recombination and dye aggregation,and enhance the driving force for dye regeneration,so as to achieve the aim of improving the photovoltaic performance of DSSCs.We have designed and synthesized four dyes: M41,M58-60,with the D-?-A basic framework: arylamine structure as electron donor,dithieno[3,2-b:2',3'-d]pyrrole(DTP)as ?-bridge and cyanoacetic acid as acceptor.The structure of important intermediates and four dyes were characterized.In addition,we tested the photophysical properties,electrochemical properties of the dyes and the photovoltaic performance,ee,IMVS,EIS of the DSSCs.Results show that:(1)The introduction of the HEYB unit in the arylamine donor(M59/M60)leads to a modest dihedral angle between the donor and spacer and downshift of HOMO.It also enhances the driving force for dye regeneration,suppresses dye aggregation and charge recombination;(2)Whether in Co-phen or iodine electrolyte,the insertion of HEYB will increase the photovoltaic performance;(3)No matter what arylamine donor is employed(bulky or small),the use of the HEYB unit in arylamine donor has a positive effect on the photovoltaic performance of dyes.(4)Under the standard AM 1.5G illumination,DSSCs based on M60 employing Co-phen electrolyte displays the best photovoltaic performance of 9.75%.