Patent ID: 7768019

Claim:
A two-terminal light-emitting device comprising: light emitting active layer comprising at least one organic semiconductor layer; a first electrode in contact with the active layer for injecting charge carriers of a first type into the active layer, at least part of the first electrode defining a first electrode plane and a thickness dimension substantially orthogonal to the first electrode plane; a patterned electrically insulating layer in contact with the active layer, at least a portion of the electrically insulating layer overlaying part of the first electrode, defining an insulating layer plane substantially parallel to the first electrode plane, defining a thickness dimension substantially orthogonal to the insulating layer plane and having a thickness along the thickness dimension that is substantially uniform, and having an edge with a thickness substantially the same as the substantially uniform thickness of the part of the electrically insulating layer, a point on the edge defining an insulating layer edge plane that is orthogonal to the insulating layer plane, the electrically insulating layer being on one side of the insulating layer edge plane and not on the other side; and a second electrode in contact with the active layer for injecting charge carriers of a second type into the active layer, the second type of charge carriers being of opposite polarity from the first type of charge carriers, at least part of the second electrode overlaying some of the portion of the electrically insulating layer that is overlaying part of the first electrode, defining a second electrode plane substantially parallel to the first electrode plane, defining a thickness dimension substantially orthogonal to the second electrode plane and having a thickness along the thickness dimension that is substantially uniform, and having an edge with a thickness substantially the same as the substantially uniform thickness of the part of the second electrode, a point on the edge defining a second electrode edge plane that is orthogonal to the second electrode plane, the second electrode being on one side of the second electrode edge plane and not on the other side, wherein the second electrode edge plane intersects both the electrically insulating layer and the first electrode, and wherein the insulating layer edge plane intersects the first electrode but not the second electrode, the insulating layer edge plane and second electrode edge plane being offset from one another by a predetermined distance so as to form an offset top surface portion of the insulating layer that does not overlap with the second electrode, wherein an accumulation layer of charge carriers is formed inside of the active layer at an interface between the active layer and the insulating layer at the offset top surface portion when a voltage is applied to the first and second electrodes so as to emit light from a region in the active layer above the offset top surface portion.