Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B33/00—Electroluminescent light sources
  • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
  • H05B33/22—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/80—Constructional details
  • H10K50/85—Arrangements for extracting light from the devices
  • H10K50/854—Arrangements for extracting light from the devices comprising scattering means
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/80—Constructional details
  • H10K50/85—Arrangements for extracting light from the devices
  • H10K50/856—Arrangements for extracting light from the devices comprising reflective means
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/81—Bodies
  • H10H20/819—Bodies characterised by their shape, e.g. curved or truncated substrates
  • H10H20/82—Roughened surfaces, e.g. at the interface between epitaxial layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/83—Electrodes
  • H10H20/832—Electrodes characterised by their material
  • H10H20/835—Reflective materials

Definitions

• the structure of the second light outcoupling layer must be adapted to the distribution of the angles of incidence.
• the distribution of the angles of incidence on the boundary surface between substrate andair depends very essentially on whether an additional first light outcoupling layer is present between a transparent electrode and a transparent substrate, which layer influences the angular distribution (angle between direction of propagation of the rays of light and the layer normal) of the light.
• a better luminous efficiency (number of light quanta outcoupled from the EL light source relative to the number of light quanta produced in the EL layer) is achieved than in EL light sources with one or more light outcoupling layers not tuned to each other.
• a first light outcoupling layer can improve the light incoupling into the substrate, without an improved light outcoupling from the EL light source being obtained.
• the non-uniform angular distribution has a maximum and an angle range of ⁇ 15 degrees around said maximum comprises more than 70% of the light, preferably more than 80% of the light, particularly preferably more than 90% of the light.
• the more light is coupled into the substrate, whose angles of incidence vary essentially only in a narrow range, the more optimally the second light outcoupling layer can be adapted to the angular distribution.
• the light outcoupling into the substrate can be additionally increased by this specific deviation from the strict periodicity in an ideal grid.
• surface structures of the second light outcoupling layer comprising square pyramidal structures, triangular pyramidal structures, hexagonal pyramidal structures, ellipsoidal dome structures or cone structures are particularly preferable.
• the second light outcoupling layer has a refractive index larger than or equal to that of the substrate, whereby total reflection at the boundary surface between substrate and second light outcoupling layer during light emergence from the substrate is avoided.
• the transparent electrode 4 can comprise, for example, p-doped silicon, Indium-doped Tin Oxide (ITO) or Antimony-doped Tin Oxide (ATO). It is also possible to produce the transparent electrode from an organic material with particularly high electrical conductivity, for example, Poly (3,4 ethylene dioxythiophene) in polystyrene sulfonic acid (PEDT/PSS, Baytron P from the company HC Starck). Preferably, the electrode 4 comprises ITO with a refractive index between 1.6 and 2.0.
• the reflecting electrode 6 itself can be reflecting, for example of a material like aluminum, copper, silver or gold, or can additionally have a reflecting layer structure.
• a further second light outcoupling layer 1 arranged on the substrate 2 at the boundary surface to air and having a surface structure 8 specially adapted to the special angular distribution n( ⁇ ) produced by the first light outcoupling layer 2 leads to an improvement of the outcoupled quantity of light in comparison to an EL light source without light outcoupling layers 3 and 1 or to an EL light source with one or more light outcoupling layers not matched to each other.
• First light outcoupling layers for producing a non-uniform angular distribution of the light outcoupled into the substrate can comprise layers with a local variation of the refractive index or layers of a matrix material with regularly or irregularly arranged centers in the matrix material for the refraction of light, light scattering or light reflection at these centers.
• Such centers can be, for example, air inclusions, defects or phase boundaries in the matrix material or particles in the matrix material or structures of materials having a higher and/or lower refractive index than the matrix material or having a reflecting surface or other centers with similar effect.
• First light outcoupling layers can be produced, for example, by thin film processes like vapor deposition or sputtering, also in combination with masking, lithography and/or etching processes for structuring the first and/or second material or by wet-chemical methods, such as so-termedspin coating with a suspension having statistically distributed particles.
• the first light outcoupling layer 3 can also comprise two or more sub-layers with different material properties. It is favorable if the thickness H 2 of the second light outcoupling layer ranges between 100 nm and 10 ⁇ m.
• the light outcoupling from an electroluminescence light source is optimized, which light source comprises a light outcoupling layer 3 as a scattering layer of a second material 10 with statistically distributed light-reflecting or refractive particles of at least one first material 9, and a second light outcoupling layer 1, which, as a surface structure 8, has an essentially planar surface with channels having steep side walls.
• Effective outcoupling of the part of the light having propagation angles larger than the critical angle is brought about by the channels between the planar areas, the side faces of the channels having a suitable depth and including an angle with the layer normal of the substrate in the range between 20 and 30 degrees.
• a suitable depth of such channels is obtained if the projected surface of all side faces, viewed in the direction of propagation of the rays of light with a large propagation angle ⁇ , is clearly larger than the projected surface of the planar areas.
• the first light outcoupling layer 3 comprises a first material 9, which is arranged in the second material, essentially in a periodic structure of a multiplicity of structural elements, in a plane parallel to the surface of the second light outcoupling layer 3, the structural elements being designed as spatial bodies, see Fig. 2.
• the structural elements can be arranged, as shown in Fig. 2, in a grid-like manner at the boundary surface between first light outcoupling layer 3 and substrate 2 or within the first light outcoupling layer 3.
• the periodic structure represents an optical grid, whose properties can be adapted, by a person skilled in the art varying the periodic structure, to the wavelength of the light emitted by the EL layer, to the layer structure and to the optical properties of the substrate.
• An example of embodiment of the electroluminescence light source in accordance with the invention comprises a first light outcoupling layer for producing a nonuniform angular distribution of the light when the light enters into the substrate, wherein the thickness H 2 of the first light outcoupling layer amounts to 700 nm, the refractive indices U 1 and n 2 of the first and second materials of the first light outcoupling layer amount to 1.42 and 1.94, respectively, the height H 1 of the structural elements in the first light outcoupling layer amounts to 220 nm and the average distance a0 between the structural elements amounts to 650 nm.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Electroluminescent Light Sources (AREA)
• Details Of Measuring Devices (AREA)

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• 2006
  • 2006-05-03 CN CNA2006800162832A patent/CN101176214A/zh active Pending
  • 2006-05-03 WO PCT/IB2006/051385 patent/WO2006120610A1/en not_active Ceased
  • 2006-05-03 US US11/913,876 patent/US20080197764A1/en not_active Abandoned
  • 2006-05-03 EP EP06744859A patent/EP1883977A1/en not_active Withdrawn
  • 2006-05-03 JP JP2008510691A patent/JP2008541368A/ja active Pending
  • 2006-05-03 KR KR1020077028947A patent/KR20080010458A/ko not_active Ceased
  • 2006-05-09 TW TW095116436A patent/TW200713640A/zh unknown

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