Sensitized solar cells consisting of a molecular or solid-state sensitizer that serves to collect light and inject an electron into a substrate that favors their migration are among the most studied photovoltaic systems at present. Despite its importance in determining the potential of a photovoltaic device, current methods for monitoring the interfacial electron transfer remain ambiguous. Now, using deep-ultraviolet continuum pulses, EPFL scientists have developed a substrate-specific method to detect electron transfer. The work is published in the Journal of the American Chemical Society.