Solution-processed semiconductors offer many advantages for energy conversion, saving and storage applications. However the underlying processes that govern electrical processes such as charge transport, the separation of photogenerated charge, and carrier recombination, are not well-understood. New experimental and theoretical approaches to correlate structure with electronic processes are valuable for gaining insights into smart design. In this talk I will discuss our recent results on coupling electrical and optical spectroscopies to study structure-function relationships in organic semiconductors, such as polaron formation and transport in donor-acceptor polymers for photovoltaics, as well as our work on applying impedance spectroscopy to study interfacial dynamics in perovskite solar cells.