An organic light emitting diode comprising a light extraction substructure and a diode superstructure, wherein: the diode superstructure comprises a cathode, an anode, and an organic light emitting semiconductor material interposed between the cathode and the anode to collectively define a superstructure waveguide; the light extraction substructure comprises a glass substrate, a plurality of discrete light extraction waveguide elements distributed over a waveguide surface of the glass substrate, and a light expulsion matrix distributed over the discrete light extraction waveguide elements and the waveguide surface of the glass substrate; the discrete light extraction waveguide elements extend between waveguide element termination points (24A,24B) along a direction of optical propagation defined by the superstructure waveguide; the light expulsion matrix is distributed at varying thicknesses to enhance the planarity of a diode superstructure-engaging side of the light extraction substructure and to provide light expulsion sites at the waveguide element termination points of the discrete light extraction waveguide elements; the superstructure waveguide and the light extraction substructure are configured such that, in operation, light originating in the organic light emitting semiconductor material of the diode superstructure is coupled to the discrete waveguide elements of the light extraction substructure as respective coupled modes having an approximate coupling length defined as the propagation distance required for an optical mode to be coupled from the superstructure waveguide to one of the discrete waveguide elements of the light extraction substructure; and the linear extent of a majority of the discrete light extraction waveguide elements between the waveguide element termination points (24A,24B) does not exceed five times the coupling length; wherein the discrete light extraction waveguide elements comprise titania, zirconia, alumina, tin oxide, zinc oxide or combinations thereof and binder; a majority of the discrete light extraction waveguide elements extend less than 20 μm between the waveguide element termination points; and characterized in that the index of refraction of the light expulsion matrix η is at least 0.2 less than the effective index of refraction of the superstructure waveguide η eff and the effective index of refraction of the discrete light extraction waveguide elements η eff; the thickness of the superstructure waveguide x and the combined thickness x (WG+P) of the discrete light extraction waveguide elements and the light expulsion matrix differ by less than 1.5 μm along a dimension perpendicular to the direction of optical propagation; and the superstructure waveguide is separated from the discrete light extraction waveguide elements by less than 1.5 μm along a dimension perpendicular to the direction of optical propagation. the diode superstructure comprises a cathode, an anode, and an organic light emitting semiconductor material interposed between the cathode and the anode to collectively define a superstructure waveguide; the light extraction substructure comprises a glass substrate, a plurality of discrete light extraction waveguide elements distributed over a waveguide surface of the glass substrate, and a light expulsion matrix distributed over the discrete light extraction waveguide elements and the waveguide surface of the glass substrate; the discrete light extraction waveguide elements extend between waveguide element termination points (24A,24B) along a direction of optical propagation defined by the superstructure waveguide; the light expulsion matrix is distributed at varying thicknesses to enhance the planarity of a diode superstructure-engaging side of the light extraction substructure and to provide light expulsion sites at the waveguide element termination points of the discrete light extraction waveguide elements; the superstructure waveguide and the light extraction substructure are configured such that, in operation, light originating in the organic light emitting semiconductor material of the diode superstructure is coupled to the discrete waveguide elements of the light extraction substructure as respective coupled modes having an approximate coupling length defined as the propagation distance required for an optical mode to be coupled from the superstructure waveguide to one of the discrete waveguide elements of the light extraction substructure; and the linear extent of a majority of the discrete light extraction waveguide elements between the waveguide element termination points (24A,24B) does not exceed five times the coupling length; wherein the discrete light extraction waveguide elements comprise titania, zirconia, alumina, tin oxide, zinc oxide or combinations thereof and binder; a majority of the discrete light extraction waveguide elements extend less than 20 μm between the waveguide element termination points; and characterized in that the index of refraction of the light expulsion matrix η is at least 0.2 less than the effective index of refraction of the superstructure waveguide η eff and the effective index of refraction of the discrete light extraction waveguide elements η eff; the thickness of the superstructure waveguide x and the combined thickness x (WG+P) of the discrete light extraction waveguide elements and the light expulsion matrix differ by less than 1.5 μm along a dimension perpendicular to the direction of optical propagation; and the superstructure waveguide is separated from the discrete light extraction waveguide elements by less than 1.5 μm along a dimension perpendicular to the direction of optical propagation.