High Efficiency Organic Dye-sensitized Solar Cells Interface Charge Transfer Kinetics Research

Solar energy has been one of the most attracting solutions on the field of new energy sources due to its characteristics of safety,cleanness,sustainability and great potential now.Since the birth of the solar cells,Silicon based solar cells?SSCs?had been possessing the leading position of world photovoltaic market.And the barrier which hindered the further development of DSSCs is the application of expensive high-purity Silicon resulting in the uneconomical production processes.Dye-sensitized solar cells?DSSCs?are the candidate of the third-generation with the advantages of simple production process,low-cost,non-toxic and flexibility.In this paper,we obtained a series of dye molecules by molecular modification of D-A type dye donors,and studied their charge transfer kinetics.Details as follows:We obtained the C276,C296,C298 and C281 dye molecules through extend the ? conjugated structures of donors as the subjects to study the influence of dye molecule structures to each kinetics progress and device performances.Firstly,femtosecond fluorescence up-conversion and time-correlated singe photon calculation technologies were combined to research the excited state kinetics of C276,C296,C298 and C281 dye molecules dissolved in tetrahydrofuran?THF?.The fitting results indicated that their equilibrium excited state lifes?????are 763.1 ps,1220 ps,862 ps and 430 ps,respectively.To further explain the operation processes of DSSCs,we also discussed the kinetics of dyes grafted on TiO₂ and Al2O3 films.We acquired the fluorescent quenching quantum yield?QYD?of the four dyes,94.6%,94.1%,94.8% and 94.6%,while the electronic injection time constants(???_ei)are 35.8 ps,41.4 ps,87.9 ps and 12.6 ps.Based the above results,we established the physicl model of electron injection progress in DSSCs.Secondly,spectroscopic electrochemistry technology and nanosecond transient absorption spectrum were employed to explore the hole injection processes of C276,C296,C298 and C281 devices.And the results showed the hole injection efficiency of the four dyes are 97%,97%,98% and 96%,respectively,which benifited from the appropriate HOME energy levels of dyes.Thirdly,we fabricated dye-sensitized solar cells with C276,C296,C298 and C281 as the sensitizers obtaining energy conversion efficiency of 9.0%,12.0%,12.0% and 13.1%.And the short-current current density?Jsc?reached 14.81 mA cm-2,18.63 mA cm-2,19.29 mA cm-2 and 21.27 mA cm-2 which benefited from the extension of conjugate skeleton and spectral response range.The changes of open-current voltage?Voc?had also been attributed to the influence of dye molecule structures to the quality of the single molecule layer.