Direct Dynamic Evidence of Charge Separation in a Dye‐Sensitized Solar Cell Obtained under Operando Conditions by Raman Spectroscopy

Abstract

Interfaces play an important role in enhancing the energy conversion performance of dye‐sensitized solar cells (DSCs). The interface effects have been studied by many techniques, but almost all studies only performed on a portion of DSC, rather than on a complete solar cell. Hence, monitoring the interface evolution of a DSC is still very challenging. Here, in situ/operando resonance Raman (RR) spectroscopic analyses were carried out to monitor the dynamic observations of the photovoltaic conversion process from a DSC. We observed the creation of new species (i.e., polyiodide and iodine aggregates) in the photosensitization process. We also successfully identified molecular‐scale dynamic evidence that the bands from the C=C of 2,2'‐bipyridyl (bpy), the S=C=N of NCS ligand and photochemical products show reasonably strong intensity and frequency changes, which clearly demonstrates that they are important pathways of charge separation. Furthermore, RR spectroscopy also be applicable to quickly evaluate the performance of DSCs.