Saving energy is one of the most important topics in technology. The conversion of energy from the source to the final outcome is of crucial importance e.g. in solar cells with the conversion of sun light into electricity or in compact fluorescent lamps with the conversion of UV-light to visible light. The conversion and specifically the conversion phosphors determine the efficiency substantially. The invention deals with coatings of special energy-conversion nanophosphors that will allow for a better device performance higher energy efficiency safer and greener production and diminish the impacts on health issues and the environment during manufacturing as well as at end-of-life. They are easily processible and therefore of versatile applicability.