A light emissive or photovoltaic device comprising: a cathode structure for injecting electrons, the cathode structure having one or more constituent regions; an anode structure for injecting holes, the anode structure having one or more constituent regions; and an organic light emissive component located between the anode structure and the cathode structure; a first charge transport layer located between the first electrode and the organic component and of a material having a refractive index greater than 1.85; wherein the device structure supports optical gain within the device.
