An electroluminescent device comprising: a substrate; one or more light-emitting elements formed over the substrate, the one or more light-emitting elements including first and second spaced-apart electrodes wherein at least one of the first and second electrodes is transparent and a light-emitting layer comprising quantum dots formed between the first and second electrodes; a cover located over the one or more light-emitting elements and spaced apart from the one or more light-emitting elements to form a gap between the cover and the one or more light-emitting elements; and separately formed spacer elements located in the gap between the cover and the one or more light-emitting elements and wherein the spacer elements are in physical contact with the one or more light-emitting elements, the cover, or both the one or more light-emitting elements and the cover.