We discuss the use of quantum dots (QDs) in electro-optic devices. The focus of the article is on key problems in this area: the electronic and optical properties of QDs, dispersing QDs in polymers and the requirements for both, and QDs and polymer composites in devices such as solar cells, light-emitting devices, and detectors. The accompanying article by Geyer et al. in this issue of ACS Nano demonstrates an excellent example of a detector device, which also points to future directions for research in this field.