A lighting device , comprising: a substrate ; two or more light-emitting elements formed over the substrate ; an affixing layer fixing the two or more light-emitting elements in place; a transparent conductive layer in electrical contact with the light-emitting elements ; the substrate and the transparent conductive layer sandwich the affixing layer with the light-emitting elements in place; wherein the affixing layer is an electrically insulating material; the two or more light-emitting elements are electrically connected to the conductive layer and the substrate via positive and negative electrical connections ; the affixing layer is doped with a photo active or photochromic material, which is a long lifetime luminescent material, the affixing layer which is doped is an integral part of the structural connection between the substrate and the transparent conductive layer , and between the light-emitting elements, the light-emitting elements are embedded in the affixing layer the lighting device being configured so that, in a first mode when the light-emitting elements are energized, the photo active or photochromic material of the affixing layer is excited by the light-emitting elements within the affixing layer itself, and in a second mode when the light-emitting elements are de-energized, the affixing layer produces a persistent luminescence, characterised in that the lighting device is configured to emit the persistent luminescence from the affixing layer for at least several minutes when the lighting device is powered down. a substrate ; two or more light-emitting elements formed over the substrate ; an affixing layer fixing the two or more light-emitting elements in place; a transparent conductive layer in electrical contact with the light-emitting elements ; the substrate and the transparent conductive layer sandwich the affixing layer with the light-emitting elements in place; wherein the affixing layer is an electrically insulating material; the two or more light-emitting elements are electrically connected to the conductive layer and the substrate via positive and negative electrical connections ; the affixing layer is doped with a photo active or photochromic material, which is a long lifetime luminescent material, the affixing layer which is doped is an integral part of the structural connection between the substrate and the transparent conductive layer , and between the light-emitting elements, the light-emitting elements are embedded in the affixing layer the lighting device being configured so that, in a first mode when the light-emitting elements are energized, the photo active or photochromic material of the affixing layer is excited by the light-emitting elements within the affixing layer itself, and in a second mode when the light-emitting elements are de-energized, the affixing layer produces a persistent luminescence, characterised in that the lighting device is configured to emit the persistent luminescence from the affixing layer for at least several minutes when the lighting device is powered down. in a first mode when the light-emitting elements are energized, the photo active or photochromic material of the affixing layer is excited by the light-emitting elements within the affixing layer itself, and in a second mode when the light-emitting elements are de-energized, the affixing layer produces a persistent luminescence, characterised in that the lighting device is configured to emit the persistent luminescence from the affixing layer for at least several minutes when the lighting device is powered down. <EOS>