The present invention relates inter alia to light- and/or irradiation-emitting fibers comprising nanocrystals, in particular quantum dots and nanorods, their preparation and use. The fiber may have a fiber core 10, an outer first electrode 20, a light emitting layer 30, a radiation transmissive second electrode 40 positioned over the organic light emitting layer 30. Eventually the fiber may also comprise an optional radiation transmissive moisture and/or air barrier layer 50 and/or an optional radiation transmissive encapsulating material 60.