nterest in a first-principles understanding of interfacial structure and dynamics of organic semiconductors has increased dramatically, driven, e.g., by vigorous efforts to develop platforms for efficient solar energy conversion. Understanding the effects of these interfaces remains, however, a formidable challenge, since interactions between chemically different molecules or molecules and surfaces may alter the molecular electronic structure in important ways. This is particularly true for the electronic structure and dynamics in the excited state manifold, where only few data are available. I will discuss several novel approaches developed in LabMonti towards understanding both electronic structure and dynamics at highly controlled interfaces, ranging from single molecule length-scales to time-resolved photoelectron spectroscopy in thin films. From such experiments emerges predictive insight into the interfacial electronic structure of organic semiconductors and novel ways of controlling and influencing charge transfer events towards efficient charge separation, currently thought to be one of the key obstacles in achieving higher solar energy conversion efficiencies.