Active matrix enhanced organic light emitting diode displays for large screen graphic display applications
View Patent ↗A light emitting photonic crystal composed of chiral liquid crystalline material and having an organic light emitting diode and methods of making the same are disclosed. An organic light emitting diode disposed within a photonic structure having a band-gap, or stop-band, allows the photonic structure to emit light at wavelengths occurring at the edges of the band-gap.
1. A light emitting device comprising:
a light emitting photonic crystal having organic electroluminescent emitter material disposed within the photonic crystal; and
a photoluminescent material disposed upon a surface of the light emitting photonic crystal, such that light emitted by the light emitting photonic crystal causes photoexcitation within the photoluminescent material;
wherein the light emitting phonic crystal is composed of polymerized chiral nematic liquid crystal material,
wherein the polymerized chiral nematic liquid crystal material comprises:
a hole transporting layer comprising the polymerized chiral nematic liquid crystal material; and
a light emitting layer comprising the polymerized chiral nematic liquid crystalline material; and
an electron transporting layer comprising the polymerized chiral nematic liquid crystal material;
wherein each of said layers has a thickness and said light emitting layer has a respective thickness that is 10% or less of a total thickness of all the polymerized chiral nematic liquid crystal material containing layers combined.
2. The light emitting device of claim 1 , wherein each layer has a plane and the polymerized chiral nematic liquid crystal material comprising each layer comprises molecules having long axes aligned parallel with said plane of said layer.
3. The light emitting device of claim 1 , wherein the polymerized chiral nematic material in each layer spontaneously adopts a helical structure with a helical pitch, and
the helical pitch of the helical structure of the polymerized chiral nematic material in each layer is the same.
4. The light emitting device of claim 1 , wherein the layers comprising polymerized chiral liquid crystal combine together to form a photonic crystal.
5. The light emitting device of claim 1 , wherein said light emitting layer further comprises an electroluminescent material which emits light into band edge light propagation modes of the light emitting photonic crystal.
6. The light emitting device of claim 1 , wherein the layers comprising polymerized chiral liquid crystal all have same ordinary and extraordinary refractive indices.