| The p-type dye-sensitized solar cells is one of the key research directions in the development of tandem dye-sensitized solar cells.Designing p-type DSSC dyes with a more reasonable structure for reducing the charge recombination between p-type dyes and semiconductor holes has gradually become a hot spot in this field.In this work we theoretically designed and synthesized the D-A1-A2structural dyes c TPAPh-Py CN2 and c TPABT-Py CN2 as p-type DSSC sensitizer,using triphenylamine as the donor,styryl or benzotriazole as the first acceptor,and dicyanovinylpyrimidine as the second electron acceptor.The photophysical and electrochemical properties of the target dyes were investigated.The results of ultraviolet-visible absorption spectroscopy and steady-state fluorescence spectroscopy showed that the light-havesting and intramolecular charge separation abilities of D-A dye c TPAPh-NO2are decreased.On the contrary,the fluorescence quenching rate of the D-A1-A2dye c TPAPh-Py CN2 and dye c TPABT-Py CN2 is 99%higher than D-A dye c TPAPh-NO2,which indicates that the attenuation pathway of the excited state of D-A1-A2dyes has changed significantly.The electrochemical performance test showed that the HOMO energy level of the dye can effectively match the energy level of the semiconductor;the LUMO energy level of the dye is around-3.6 e V,which indicates that can effectively complete the regeneration of the excited dyes.The transient fluorescence test results in toluene solvent showed that the dye c TPAPh-Py CN2 and c TPABT-Py CN2 can observe two fluorescence decay lifetimes,of which the high-proportion short lifetime can be attributed to the process of intramolecular electron transfer.The D-A1-A2dye c TPABT-Py CN2 were applied for p-type DSSC device and the photovoltaic device data is JSC=1.97 m A/cm2,VOC=144 m V,FF=36.0%,η=0.103%.The results showed that the photovoltaic device efficiency of the D-A1-A2dye is 1.8 times higher than the c TPAPh-NO2.The better test results could be attributed to the design of the whole molecule,which leads to higher charge-separated efficiency and better spectral absorption. |
