Developing materials for optical and electrical applications often requires an understanding of the relationships between processing and point defects. Atomic scale relationships such as these are frequently elusive to understand due to a lack of characterization techniques. As recently demonstrated by our group, point defects in oxides and semiconductors can be quantified chemically and spatially at near atomic resolution through atom probe tomography (APT). Specifically, the relationship between ordered defect pair point defect chemistries and the resulting optoelectronic properties in Cu(In,Ga)Se2 thin film photovoltaic absorber layers will be illustrated. Similarly, oxygen stoichiometries in oxygen and proton conducting oxides can be directly related to the electrical conductivities where grain boundaries dominate transport. Laser assisted APT also allows for unique opportunities for measuring atomic diffusion where thermal transport can assist transformations from metastable states. Using a “Dynamic” atom probe, atomic scale diffusion can be quantified at the atomic scale in 3-dimensions using a combination of APT and in-situ electron diffraction with a temporal resolution of better than 1 ns.