Quantitative investigation of local electric field through absorption spectrum in dye-sensitized solar cells: Atomistic simulations

摘要

The local transient electric field in dye-sensitized solar cells (DSSCs), created by heterointerfacial charge transfer on illumination, exerts an important role in the internal photoelectronic processes occurring at dye/semiconductor heterointerface in the time-resolved measurement, for example, transient absorption spectroscopy. Herein, on the basis of theoretical simulations, we proposed a general strategy to quantitatively examine the nature of local electric field (microscopic nature) through absorption spectra of adsorbed dye molecule (macroscopic observation). A controllably modulated external electric field is imposed on the sensitized system to couple to local electric field, resulting in the absorption spectrum shift of ground-state dye molecules. By fitting absorption spectrum under applied external electric field with Gauss-Stark equation, the quantitative property of local electric field would be obtained. The Gauss-Stark equation reflects the quantitative relationship between the local electric field and absorption spectrum shift of adsorbed ground-state dye molecule. Our study not only provides origin and magnitude of Stark effect in DSSCs but also offers a promising route to explore the elementary photoelectronic processes experimentally and theoretically.