Comparison of Donor-Acceptor $π$-Conjugated Dyes in Model Solar Cells: A Study of Interfacial Ultrafast Electron Migration

Abstract: Interfacial ultrafast electron migration processes are simulated in finite cluster models of dye-sensitized solar cells within a single active electron approach. Initially, three different donor-acceptor $\pi$-conjugated dyes supported on colloidal titania clusters are compared from the perspective of their optical and electronic properties. The potential performance of the model solar cell devices for charge migration processes is predicted from a static perspective. For this purpose, parameter-free expressions for state-resolved injection times and currents are established and evaluated for the three systems. A broadband laser excitation promoting the excited states in the visible region initiates the electron migration process. The evolution of the electronic wave packet is analyzed with a density-based toolset including the electronic yields partitioned for characteristic fragments of the model complexes and the time-dependent one-electron density for distinctive time steps in the dynamics. On the one hand, these reveal a microscopic picture for the mechanistic pathway of the charge migration and on the other hand, they validate the results from the time-independent analysis concerning the photovoltaic efficiency.