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

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.