# US 10,483,496 B2 · Electroluminescent devices with improved optical out-coupling efficiencies > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,483,496 B2 - Document ID: US10483496B2 - Status: Granted - Kind: B2 - Application number: 15/668,894 - Filed: 2017-08-04 - Published: 2017-12-14 - Granted: 2019-11-19 - Earliest claimed: 2015-03-11 - Assignees: National Taiwan University - Applicants: National Taiwan University - Inventors: Chung-Chih Wu; Chun-Yu Lin; Wei-Kai Lee; Min Jiao; Hoang Yan Lin; Guo-Dong Su - Web page: https://patentgrep.com/patent/US10483496B2 ## CPC - H10K 59/879: {comprising refractive means, e.g. lenses} - H10H 20/856: Reflecting means - H10K 59/122: Pixel-defining structures or layers, e.g. banks - H10K 59/80: Constructional details - H10K 59/877: {comprising scattering means} - H10K 2102/351: {Thickness} - H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES - H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS ## Abstract An electroluminescent (EL) device is disclosed. An optically reflective concave structure includes a first surface and a second surface that lies at an angle relative to the first surface, wherein at least the first and second surfaces are optically reflective. One or more functional layers include a light emitting layer, disposed over the surfaces of the optically reflective concave structure, wherein at least one electroluminescent area of the light emitting layer is defined on the first surface. Especially, the ratio between the diameter of the first surface and the thickness of the one or more functional layers in the optically reflective concave structure is smaller than a constant value. ## Claims ### Claim 1 An organic electroluminescent device, comprising: an optically reflective concave structure, comprising: a first optically reflective surface; and a second optically reflective surface, intersecting said first optically reflective surface at an obtuse angle; a first light propagation layer in direct contact with said first optically reflective surface and said second optically reflective surface, comprising: a first refractive surface, parallel to and separated from said first optically reflective surface; a second refractive surface, parallel to and separated from said second optically reflective surface; and an electroluminescent area, disposed entirely within said first light propagation layer, between said first optically reflective surface and said first refractive surface, without directly contacting any of said first optically reflective surface, said second optically reflective surface, said first refractive surface and said second refractive surface; and a second light propagation layer, disposed on the first light propagation layer, wherein said second light propagation layer has a greater refractive index than said electroluminescent area minus 0.2. ### Claim 2 (depends on 1) The organic electroluminescent device of claim 1, wherein said electroluminescent area is defined by a patterned interlayer. ### Claim 3 (depends on 1) The organic electroluminescent device of claim 1, wherein said first light propagation layer further comprises a bend at the obtuse angle, and light emitted from the electroluminescent area propagating through said first light propagation layer is re-directed and out-coupled to air by the bend. ### Claim 4 (depends on 1) The organic electroluminescent device of claim 1, wherein said first light propagation layer further comprises: a first portion, having a first thickness, and disposed over the first optically reflective surface; and a second portion, having a second thickness less than said first thickness, and disposed over the second optically reflective surface, wherein light emitted from the electroluminescent area propagating from the first portion to the second portion is re-directed and out-coupled to air by the decrease in thickness from the first thickness to the second thickness. ### Claim 5 (depends on 1) The organic electroluminescent device of claim 1, wherein the ratio between a diameter of the first optically reflective surface and a thickness of the first light propagation layer is smaller than 200. ### Claim 6 (depends on 1) The organic electroluminescent device of claim 1, wherein the ratio between a diameter of the first optically reflective surface and a combined thickness of the first light propagation layer and the second light propagation layer is smaller than 60. ### Claim 7 (depends on 1) The organic electroluminescent device of claim 1, wherein the light emitted from the electroluminescent area is re-directed and out-coupled to air, and the number of reflection of the reflected or total internal reflected light and corresponding optical loss is reduced before being re-directed and out-coupled, when propagating in the first light propagation layer and second light propagation layer. ### Claim 8 (depends on 1) The organic electroluminescent device of claim 1, wherein the first light propagation layer and the second light propagation layer have a transparency of more than 75% in the wavelength range of the light emitted from the electroluminescent area. ### Claim 9 (depends on 1) The organic electroluminescent device of claim 1, wherein the exposed surface of the second light propagation layer is flat or curved. ### Claim 10 (depends on 1) The organic electroluminescent device of claim 1, wherein the optically reflective concave structure consists of a material selected from the group consisting of metal and scattering reflector. ### Claim 11 (depends on 1) The organic electroluminescent device of claim 1, wherein the optically reflective concave structure is made of a material selected from the group consisting of metal, transparent conductive metal-oxide, transparent dielectric, scattering reflector, distributed Bragg reflector formed by alternate stacking of high-index/low-index materials, their stacking and their combinations. ### Claim 12 (depends on 1) The organic electroluminescent device of claim 1, wherein a material of the first optically reflective surface is same as a material of the second optically reflective surface. ### Claim 13 (depends on 1) The organic electroluminescent device of claim 1, wherein a material of the first optically reflective surface is different from a material of the second optically reflective surface. ### Claim 14 (depends on 1) The organic electroluminescent device of claim 1, wherein the optically reflective concave structure further comprises a third surface adjoining said second optically reflective surface and parallel to said first optically reflective surface, and the electroluminescent area is extended to the intersection of the second and third surfaces. ### Claim 15 (depends on 1) The organic electroluminescent device of claim 1, wherein the first optically reflective surface and the second optically reflective surface have an optical reflectance greater than 80% in the wavelength range of the light emitted from the electroluminescent area. ### Claim 16 (depends on 1) A display including said organic electroluminescent device of claim 1, comprising: a substrate; a thin-film transistor, formed on the substrate; and an interconnection conductor, electrically connected to the thin-film transistor, wherein said electroluminescent device electrically connects to the interconnection conductor via the first optically reflective surface. ### Claim 17 (depends on 16) The display of claim 16, wherein the interconnection conductor also serves as the first optically reflective surface. ### Claim 18 (depends on 16) The display of claim 16, wherein said first optically reflective surface and said second optically reflective surface are non-conductive, and said first light propagation layer includes a first electrode electrically connected to the interconnection conductor. ### Claim 19 (depends on 1) A display including said organic electroluminescent device of claim 1, comprising: a substrate; a thin-film transistor formed on the substrate; and an interconnection conductor, electrically connected to the thin-film transistor, wherein said electroluminescent device electrically connects to the interconnection conductor via a third surface of the optically reflective concave structure adjoining said second optically reflective surface and parallel to said first optically reflective surface. ### Claim 20 (depends on 19) The display of claim 19, wherein the interconnection conductor also serves as the first optically reflective surface and the second optically reflective surface. ### Claim 21 (depends on 1) The organic electroluminescent device of claim 1, wherein the electroluminescent area emits light directly to said first optically reflective surface as bottom-emitting, and emits light directly to said first refractive surface as top-emitting. ### Claim 22 (depends on 1) The organic electroluminescent device of claim 1, further comprising a waveguide for directing light.