Single-molecule electrical characterization of photoinduced aggregation evolution

Elucidating the structural evolution of molecules during photoinduced aggregation remains a central challenge in molecular science, particularly in solution where aggregation processes occur dynamically. Here, we present an electrical strategy to characterize the evolution of photoinduced aggregation at the single-molecule level. Using persulfurated arenes as a model system, photoexcitation enhances intermolecular interactions that drive molecular assembly and induce conformational stabilization within aggregated species once the irradiation is halted. These stabilized conformations generate distinct ratiometric conductance signatures that can be reliably detected using scanning tunneling microscope-break junction measurements. Time-dependent irradiation experiments reveal the progressive evolution of aggregation, enabling electrical monitoring of structural changes during the assembly process. Complementary theoretical analyses further reveal the correlation between molecular geometry and conductance response. This work establishes a direct link between photoinduced aggregation evolution and single-molecule conductance, providing an electrical perspective for investigating structural dynamics in photoresponsive molecular assemblies.