Electronic structure and charge transfer at heterogeneous functional interfaces in energy conversion devices

The interfaces between photoactive materials or molecular sensitizers and solid electrodes play a key role in determining the performance of advanced photovoltaic and photoelectrochemical cells. They regulate band alignment, facilitate charge separation, and mitigate recombination pathways, ultimately tuning both device efficiency and long-term operational stability. This topical review provides an atomistic perspective on functional interfaces in dye-sensitized solar cells, dye-sensitized photoelectrochemical cells, and perovskite solar cells, emphasizing the role of interfacial electronic structure in governing crucial charge-transfer processes. We highlight the synergy between photoelectron spectroscopy and first-principles simulations, including density functional theory (DFT), hybrid functionals, and beyond-DFT methods, to quantify band offsets, interface dipoles, defect states, and electronic coupling. Approaches to model charge-transfer dynamics, such as projection operator diabatization and non-adiabatic methods, are also discussed. By integrating experimental observations with predictive modeling, this review outlines rational design strategies for optimizing heterogeneous functional interfaces in solar energy conversion technologies.