The scientific work of Albrecht Winnacker focused originally on the properties of point defects in solids in general and compound semiconductors in particular. Later crystal growth of new compound semiconductors like SiC and AlN and investigation of their physical properties and growth behavior was added, particularly in view of application in light emitting diodes and power electronics, resulting in availability of high quality SiC wafers for large scale industrial applications. The work on compound semiconductors was accompanied by the search for light converting materials in view of improving efficiency and spectral properties in luminescence converting light emitting diodes (LUCOLEDs). Part of this work was also dedicated to problems of optical and X-ray data storage. With the upcoming of organic electronics the focus of work shifted towards electronic and optical properties of polymer materials for application in OLEDs and solar cells.