WO2014006538A1 - Dispositif électroluminescent organique - Google Patents

Dispositif électroluminescent organique Download PDF

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Publication number
WO2014006538A1
WO2014006538A1 PCT/IB2013/055206 IB2013055206W WO2014006538A1 WO 2014006538 A1 WO2014006538 A1 WO 2014006538A1 IB 2013055206 W IB2013055206 W IB 2013055206W WO 2014006538 A1 WO2014006538 A1 WO 2014006538A1
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WO
WIPO (PCT)
Prior art keywords
substrate
area
light
areas
light extraction
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PCT/IB2013/055206
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English (en)
Inventor
Georg Friedrich Gaertner
Horst Greiner
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Koninklijke Philips N.V.
Philips Deutschland Gmbh
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Application filed by Koninklijke Philips N.V., Philips Deutschland Gmbh filed Critical Koninklijke Philips N.V.
Publication of WO2014006538A1 publication Critical patent/WO2014006538A1/fr

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/80—Constructional details
    • H10K59/875—Arrangements for extracting light from the devices
    • H10K59/879—Arrangements for extracting light from the devices comprising refractive means, e.g. lenses

Definitions

  • the invention relates to the field of organic electroluminescent devices with improved light out-coupling and to a method to manufacture such OLEDs.
  • OLEDs organic light- emitting diodes or organic electroluminescent devices
  • a typical OLED structure deposited on top of the subtrate consists of a thin transparent anode, a hole transport layer, a light emission layer (or layer stack), an electron transport layer and a cathode layer.
  • This portion of light emitted into air can be increased by a number of measures to about 36 % of the initially amount of light generated in the light emitting layer, which is still too low for an efficient use of the OLED.
  • One measure to increase the light coupled into the substrate to about 80%> is using e.g. a high index glass, where the refractory index n is about equal to the average n of the OLED layers.
  • a significant amount of the light is trapped within the transparent substrate and part of it is emitted through the side face of the substrate (side emission) and hence does not contribute to front emission. The amount of light emitted through the side faces will increase with increasing refractive index n of the substrate.
  • the side faces of the substrate are covered by a non transparent OLED housing. Therefore the light emitted through the side faces of the subtrate is lost for illumination purposes.
  • the incorporation of light scattering particles in the transparent substrate or the application of a suitably structured surface out- coupling layer can improve the light emission into air by statistically improving the escape chance.
  • a suitably structured surface out- coupling layer e.g. micro lens array
  • US 2012/0057100 Al discloses multiple examples of such additional light-outcouling layer structures comprising a transparent array of microlenses with concave, convex or pyramid-like shaped surfaces applied on one side of a transparent substrate carrying the OLED layer structure on the other side.
  • the light out-coupling has to be further increased.
  • an organic electroluminescent device comprising a transparent substrate with a thickness D with a first side and a second side opposite to the first side, wherein the substrate comprises at least one bowl shaped light extraction element, the light extraction element comprises an outwardly shaped first area and an inwardly shaped second area opposite to the first area, where the first side of the substrate comprise the outwardly curved first area of the light extraction element and the second side of the substrate comprises the inwardly curved second area of the light extraction element and a third area at least separating the second area from the first area, wherein an electro- luminescent layer stack comprising at least one organic light emitting layer stack arranged between a first and a second electrode is deposited on top of the first side of the substrate and the light emitted by the organic electroluminescent device is emitted through the second side of the substrate.
  • OLED organic electroluminescent device
  • the organic electroluminescent device strongly improves the light out- coupling through the second side of the substrate, which is the front side of the OLED used for illumination purposes.
  • OLEDs according to the present invention provide a higher overall brightness compared to OLEDs with planar substrates with parallel first and second sides having no light extraction elements when being operated at the same operating conditions.
  • the improvement is achieved by directing the formally non-desired side emission (loss of light inside the OLED housing) occurring in planar substrates according to state of the art to the light-emitting front side (second side) of the substrate, when being shaped in accordance to the present invention.
  • the third area as part of the second side of the substrate corresponds to the side of a planar substrate perpendicular to the light-emitting direction, but bended towards the light-emitting direction in the present invention. Therefore the side-emitted light of planar substrate is no longer lost for illumination purposes with the present invention due to the arrangement of the third areas as part of the light-emitting front side.
  • a transparent substrate denotes any substrate which provides a sufficient transparency at least in the visible spectrum enabling to illuminate objects, areas or volumes such as rooms with the OLED.
  • the transparency should be at least 90% or more.
  • the size of the light extraction element depends on the desired performance of the OLED.
  • the OLED comprises the entire substrate as one light extraction element.
  • the one or more light extraction elements of the substrate have a bowl shape, which denotes any three dimensional shape suitable to enhance the light out-coupling through the second side, where one side of the bowl is outwardly shaped (first area) and the opposite side of the bowl is inwardly shaped (second area). Therefore, a bowl shape light extraction element comprises a deepening surrounded by a third area facing towards the light-emission direction of the OLED.
  • the inwardly shaped second area might be established by flat sub-sections arranged in a certain angle between adjacent flat sub-section to establish the inwardly shaped second area using multiple sub-section or might be shaped according to a certain curvature.
  • the cross section of the bowl shape might be a U-like cross section, a cross section of a half sphere or any other cross section, where the legs around the deepening in the middle of the bowl shape are directed towards the light emission direction of the OLED.
  • an OLED with one bowl shaped light extraction element might by an OLED, where the electroluminescent layer stack is deposited on the outer side (outwardly shaped first area) of a substrate having the shape of a half-sphere, where the OLED housing is attached to the outer area of the first side of the substrate establishing a rim around the third area of the second side without covering the third area.
  • the emission of light from an OLED in general has an angular distribution depending on the properties of the substrate and the structure of the OLED, where the light-emission direction of the OLED corresponds to the direction, where the angular dependent intensity of the emitted light has a maximum (average light- emission direction).
  • Different examples of light extraction elements with bowl shapes according to the present invention are illustrated in details in the figures.
  • the lateral size of the substrate is defined by the extension of the substrate perpendicular to the light-emission direction.
  • the lateral size of the OLED may vary for different applications. Very large lateral sizes of light emitting front sides of OLEDs can be achieved by using large substrate sizes or by using a large light source established by a large number of smaller OLED tiles arranged adjacent to each other.
  • the substrate material might be any suitable material transparent at least in the visible spectrum, e.g. glass, plastic, or PMMA.
  • the organic light emitting device comprising at least one organic light emitting layer within the electroluminescent layer stack.
  • the organic light emitting device may utilize organic small molecules or polymers to produce light.
  • OLEDs may be referred to as small molecule organic light emitting devices (SMOLEDs) or polymer light emitting devices (PLEDs).
  • SMOLEDs are preferred because of their better light emission performance.
  • the substrate might be made of a transparent material, e.g. glass or plastic.
  • the first side of the substrate facing towards the electroluminescent layer stack is also denoted as the backside of the substrate.
  • the second side of the substrate opposite to the back side is the light emitting side.
  • the first and second electrodes act as anode and cathode (or vice versa) to provide the operational voltage to the organic light emitting layer.
  • the electroluminescent layer stack may comprise a plurality of organic layers (organic layer stack) arranged between the electrodes (anode and cathode), such as hole transport layer, electron transport layer, hole blocking layers, electron blocking layers, one or more light emitting layers or one more light emitting layer stacks, e.g.
  • the electrode deposited on top of the substrate is a transparent anode, e.g. made of indium-tin-oxide (ITO).
  • the second electrode typically the cathode, is made of a reflective metal, e.g. Al.
  • the ITO-anode is sputtered while the organic layer stack and the second electrode (AL-cathode) are evaporated to prepare the electroluminescent layer stack of the organic light emitting device.
  • the electroluminescent layer stack may comprise in addition to the organic layer stack one or more organic layers arranged on top of the second electrode acting as organic index matching layer to adapt the optical properties of the electroluminescent layer stack such as refractive index and reflectivity in order to enhance the light out-coupling out of the OLED.
  • the OLED may further comprise a cover lid sealed to the substrate in order to establish an encapsulation around the electroluminescent layer stack to prevent moisture or oxygen penetrating to the organic layers within the electroluminescent layer stack.
  • a suitable sealing material to provide a gastight seal is glass frit.
  • the material of the cover lid might be metal, ceramic material or glass.
  • the encapsulation might be provided as thin film encapsulation on top of the topmost layer of the electroluminescent layer stack.
  • an array of the bowl shaped light extraction elements are arranged adjacent to each other, where the first side of the substrate comprise the outwardly curved first areas of the array of light extraction elements and the second side comprises the inwardly curved second areas of the array of light extraction elements and the third area separates the second areas from each other, wherein the electroluminescent layer stack at least partly covers the outwardly shaped first areas of the array of light extraction elements.
  • the electroluminescent layer stack may cover each first area separately or may cover the first areas completely with one contiguous electroluminescent layer.
  • the second area of such OLED provides a lower brightness, while the third area provides a high brightness.
  • a more homogeneous brightness is preferred.
  • the OLED provides a homogeneous brightness impression for human eyes.
  • Using an array of bowl shaped light extraction elements enables to use multiple bowl shaped light extraction elements each having a small lateral extension. For each small light extraction element, one obtains the same brightness distribution as described previously for the one big bowl shaped light extraction element.
  • the overall brightness impression for human eyes is a homogeneous brightness impression.
  • the manufacturing depth of bowl shaped light extraction elements scales with the lateral size of the light extraction elements.
  • an OLED with a substrate comprising an array of bowl shaped light extraction elements can be manufactured with a significantly decrease manufacturing depth compared to the case of an OLED arranged on one single spherical shaped substrate.
  • the third area is a flat area facing into a direction, where an angular dependent intensity of light emitted by the organic electroluminescent device has a maximum, also denoted a light emission direction of the OLED.
  • the light generated within the light emitting organic layer is out-coupled from the electroluminescent layer stack into the substrate. Since the light emission within the electroluminescent layer stack occurs in any direction, the light within the substrate reaches the interface between substrate and air in a random angle of incidence. Depending on the angle of incidence and the refractive index of the transparent substrate, the light will be (out-coupled) emitted into air via the second area or be totally reflected from the interface to be trapped inside the substrate traveling towards the third areas.
  • the third areas are facing towards the light emission direction of the OLED, the light trapped within the substrate by light-guiding between first and second areas of the substrate will arrive at the interface between third area and air in an angle of incidence, which is smaller than the angle of total reflection. Therefore the amount of light initially trapped inside the substrate will be out-coupled to air via the third areas. This effect is independently from the exact shape of the bowl shaped light extraction elements, the number of present bowl shaped elements, even in case of the entire substrate just forming one single bowl shaped light extraction element.
  • an average distance between the first and second areas of the substrate defines the thickness D of the substrate with D ⁇ 1.0 mm, preferable D ⁇ 1.4 mm, more preferably D ⁇ 2.0 mm.
  • the side emission can be increased by using thicker substrates and by suitably bending these substrates to redirect the light also to the front side leading to an increased light out-coupling and therefore increased brightness of the OLED.
  • an index matching layer made of a high index material is arranged between the first side of the substrate and the electroluminescent layer stack.
  • the index matching layer is typically arranged in contact to the ITO anode.
  • the light out-coupling of light generated within the electroluminescent layer stack into the substrate can be further improved by applying additional measures such as light scattering structures (e.g. a layer with a rough interface structure) or a micro-lens array arranged between electroluminescent layer stack and substrate. Also scattering particles might be embedded in the index matching layer.
  • additional measures such as light scattering structures (e.g. a layer with a rough interface structure) or a micro-lens array arranged between electroluminescent layer stack and substrate.
  • scattering particles might be embedded in the index matching layer.
  • the total amount of light reflected by the two interfaces of electroluminescent layer stack-to-index matching layer and index matching layer-to-substrate is reduced compared to the OLED having no index matching layer between the electroluminescent layer stack and the substrate. Therefore more light will out-coupled from the electroluminescent layer stack into the substrate when using an index matching layer in between. Accordingly, the increased amount of light out-coupled to the substrate leads to an increased the amount of light coupled out from the substrate to air, since the angle of incidence of the light at the interface between second area and air does not influence the total amount of light coupled out to air, but only the local area, where the light is coupled out to air.
  • the amount of light being totally reflected at the interface between second area and air will be coupled out to air via the third areas.
  • light totally reflected by the second areas in planar substrates will lead to emission through the sides of the substrate covered by the OLED housing and therefore will not contribute to the OLED brightness.
  • the introduced index matching layer allows to apply cheap substrate materials such as float glass.
  • Substrates made of high index material enable an improved light out-coupling from the electroluminescent layer stack into the substrate until nearly 100%. Accordingly the index matching layer might be avoided.
  • the outwardly shaped first areas and the inwardly shaped second area are shaped like a part of a sphere with a first radius of the sphere of the outwardly shaped first areas and a second radius of the sphere of the inwardly shaped second areas, where the first radius is larger than the second radius.
  • the light guiding of light being totally reflected from the interface between second area and air towards the third areas for coupling out the guided light into air is improved when using transparent spherical shapes as bowl shaped light extraction elements, especially half-spheres as first and second areas.
  • the improvement relates to the overall reduced number of total reflection inside the substrate until the guided light reaches the third area of the second side of the substrate.
  • the amount of material needed for preparing the bowl shaped light extraction elements is minimized in case of half spheres.
  • the second radius ranges between 2 mm and 6 mm and a ratio between first radius and second radius ranges between 1.5 and 2.0.
  • the thickness D equals the difference between first and second radius.
  • the first side of the substrate comprises rounded edges as boundary between adjacent first areas and/or the second side comprises rounded edges as boundary between second and third areas. A second side comprising rounded edges is easier to be manufactured. A first side with rounded edges between the outwardly shaped first areas makes it easier to deposit a continuous and non-disturbed electroluminescent layer stack across adjacent bowl shaped light extraction elements.
  • a metal grid with a high electrical conductivity is applied on the first side in contact to the first electrode of the electroluminescent layer stack, where the metal grid is arranged at a boundary between adjacent first areas.
  • the first electrode is made of ITO material exhibiting a medium electrical conductivity, which may result in a voltage drop leading to an mhomogeneous current distribution across the first electrode in case of large sizes of the first electrode. Any inhomogeneous current distribution may lead to inhomogeneous light generation, which should be avoided.
  • a metal grid with a high electrical conductivity is able to distribute the current across the entire grid area without any inhomogeneity.
  • the grid is in contact to each of the first areas of each light extraction element of the array of light extraction elements, therefore the remaining ITO areas are limited to the size of a single first area, which is small enough to be able to neglect current distribution effects within each first area.
  • the metal grid may consist of aluminum or copper and might be manufactured on top of the first side by evaporating or sputtering or any other suitable technique for providing a structured layer.
  • the arrangement of the metal grid at the boundaries of adjacent light extraction elements is advantageous, because the metal grid is not visible at this position since the light emission through the third areas directly above the boundaries of adjacent light extraction elements does not originate from areas close to the boundaries of adjacent light extraction elements.
  • the substrate of the present invention allows applying a metal grid on top of the first side for current distribution purposes, which is invisible.
  • the electrode of the electroluminescent layer stack arranged on the side of the electroluminescent layer stack facing away from the substrate is made of reflective material. Therefore all light generated inside the electroluminescent layer stack will be reflected towards the substrate and subsequently coupled out to air further improving the brightness of the OLED with the substrate as the light emitting side of the OLED.
  • the invention further relates to a method to manufacture an organic electroluminescent device according to the present invention with a substrate comprising an array of the bowl shaped light extraction elements arranged adjacent to each other, comprising the step of
  • the supporting grid has a honeycomb-like structure
  • the supporting grid might be made of any suitable material being sufficient temperature resistant, e.g. a support grid made of metal or ceramic material. Suitable temperature to deform a glass substrate are above the respective glass transition temperature and can be in the order of 700 -900°C or higher, depending on the type of glass.
  • the heating might be executed in a corresponding oven large enough for placing the supporting grid and the substrate inside and suitable of being heated at least up to the temperature suitable to deform the transparent substrate.
  • the supporting grid will provide enough empty space underneath the grid to let the bowls being developed without any disturbance.
  • the grid has a height larger than the vertical extension of the bowl shaped light extraction elements. Such a grid can be placed e.g. directly on top of a table and still providing enough empty space underneath the grid to let the bowls being developed without any disturbance.
  • the supporting grid is a conductive metal grid and the metal grid is heated electrically to heat the substrate.
  • any oven and the related infrastructure can be avoided.
  • a simple power supply is required. The heating can be executed at any suitable location without requiring any additional measures or technical infrastructure.
  • the preparation process of the electroluminescent layer stack and the preparation process and preparation location of the substrate can be totally decoupled.
  • the depositing machines and processes suitable for depositing the electroluminescent layer stacks on flat substrates can be further applied even for manufacturing OLEDs with substrates comprising bowl shaped light extraction elements.
  • the gluing is executed with a transparent material with a suitable refractive index n > 1.6, preferably n > 1.7, more preferably n > 1.8, in order to act as an index matching glue. With such an index matching glue the same effects as provided by index matching layers can be achieved.
  • Fig. 1 prior art OLEDs with planar substrates in a side view
  • Fig. 2 an embodiment of an OLED according to the present invention with only one light extraction element extending over the entire substrate in a side view.
  • Fig. 3 another embodiment of an OLED according to the present invention with an array of spherical shaped light extraction elements in a side view.
  • Fig. 4 two embodiments of an OLED according to the present invention with an array of (a) V-shaped light extraction elements, and (b) U-shaped light extraction elements comprising rounded edges in a side view.
  • Fig. 5 an embodiment of an OLED according to fig.3 additionally comprising an index matching layer.
  • Fig. 6 an embodiment of an OLED according to the present invention with an array of circular-shaped light extraction elements in a top view.
  • Fig. l shows an OLED 1-PA according to prior art comprising a planar substrate 2F arranged in a housing 6, where the electroluminescent layer stack 4 is deposited on the backside BS of the substrate 2F generating light 51, 53.
  • the sizes of the shown components are not true to scale for ease of understanding.
  • the light 51 (dashed arrow) is out-coupled through the front side FS of the substrate 2F.
  • generated light 53 (closed arrow) will be totally reflected at this interface, if the angle of incidence is larger than the critical angle depending on the refractive index of the substrate 2F. This reflected light will reach the interface at the side S of the substrate.
  • the light 53 will emitted through the side S of the substrate 2F into the housing of the OLED 1-PA and will therefore not contribute to the light 5 emitted from the OLED 1-PA.
  • the light 5 indicates the average light emitting direction of the light emitted from an OLED.
  • Light emission 5 has an angular distribution, where several light paths emitted from the interface substrate - air are shown here. The maximum intensity is emitted in a direction perpendicular to the surface of the front side FS. Typically 20 - 25% of the light generated in the electroluminescent layer 4 is emitted in air (light 5).
  • Fig. 2 shows an embodiment of an OLED 1 according to the present invention with only one light extraction element 3 extending over the entire substrate 2 in a side view.
  • the sizes of the shown components are not true to scale for ease of understanding.
  • the organic electroluminescent device 1 is arranged in a housing 6 and comprises a transparent substrate 2 with a thickness D having a first side 21 and a second side 22 opposite to the first side 21. Any suitable transparent material can be used as a substrate, e.g. glass, plastic or PMMA.
  • the first side 21 corresponds to the back side BS of fig.1.
  • An electroluminescent layer stack 4 comprising at least one organic light emitting layer arranged between a first and a second electrode is deposited on top of the first side 21 of the substrate 2.
  • the light generated in the electroluminescent layer stack 4 is coupled into the substrate 2 and finally emitted as light 5 through the second side 22 of the substrate 2.
  • the substrate 2 comprises in this embodiment one bowl shaped light extraction element 3 extending over the entire substrate 2.
  • the bowl shape corresponds to a spherical shape.
  • the light extraction element 3 comprises an outwardly shaped first area 31 corresponding to the entire first side 21 of the substrate 2 and an inwardly shaped second area 32 opposite to the first area 31.
  • the second side 22 of the substrate 2 comprises the inwardly curved second area 32 of the light extraction element 3 and a third area 33 separating the second area 32 from the first area 31 as a surrounding rim around the second area 32.
  • the third area 33 is arranged as a flat area facing into a direction, where an angular dependent intensity of light 5 emitted by the organic electroluminescent device 1 has a maximum.
  • the third area 33 might be shaped differently, e.g. having a rough surface or being outwardly curved and/or having round edges.
  • the advantage of the organic electroluminescent device 1 according to the present invention is, that the side emission of planar substrate occurs via the third area 33, which is arranged in an upwards direction now being part of the light 5 emitting front side of the substrate 2.
  • the light 51 (dashed arrow) is directly through the second area 32, because the angle of incidence at the interface between second area 32 and air is smaller than the critical angle for total reflection.
  • the light 52 (closed arrow) traveling along a light path having an angle of incidence, which leads to a total reflection at the interface between second area 32 and air will impinge on the third area 33 at a more perpendicular angle and will therefore being coupled out to air through the third area 33 in order to contribute to the light 5 emitted from the OLED.
  • the substrate as shown in fig.1 nearly all light present in the substrate can be out-coupled into air independently from the refractive index of the substrate.
  • the emission through the second area 32 has a larger contribution to light 5 emitted from the OLED 1.
  • the emission through the third area 33 has a larger contribution to light 5 emitted from the OLED 1.
  • the overall brightness of the OLED 1 will be increased, because more light can be out-coupled from the electroluminescent layer stack 4 into the substrate 2, which will leave the substrate either through second are 32 or through third area 33.
  • the lateral extension LE of the bowl shaped light extraction element 3 (here bowl shape corresponds to a half-sphere-shape) corresponds to the extension of the substrate perpendicular to the emission direction of light 5.
  • Electroluminescent layer stacks 4 are deposited by deposition techniques suitable to coat curved surfaces, e.g. thermal evaporation or sputtering from differently arranged sources or certain in-line coating machines.
  • the electrode of the electroluminescent layer stack 4 arranged on the side of the electroluminescent layer stack 4 facing away from the substrate 2 is made of reflective material, e.g. Al or Ag. Skilled people will contact the electroluminescent layer stack suitably to a power supply in order to apply the operating voltage to the electroluminescent layer stack.
  • the contacting can be executed by well known techniques from OLEDs and is therefore not shown here. People skilled in the art will chose required encapsulation of the electroluminescent layer stack, which are also not shown here.
  • Fig. 3 shows another embodiment of an OLED 1 according to the present invention with an array A of spherical shaped light extraction elements 3 in a side view.
  • the bowl shape corresponds to a spherical shape.
  • the substrate 2 comprises an array A of the bowl shaped light extraction elements 3 arranged adjacent to each other, where the first side 21 of the substrate 2 comprise the outwardly curved first areas 31 of the array A of light extraction elements 3 and the second side 22 comprises the inwardly curved second areas 32 of the array A of light extraction elements 3 and the third area 33 separates the second areas 32 from each other, wherein the electroluminescent layer stack 4 at least partly covers the outwardly shaped first areas 31 of the array A of light extraction elements 3 extending across several adjacent first areas 31 as a contiguous layer.
  • the average distance between the first and second areas 31, 32 of the substrate 2 defines the thickness D of the substrate 2 with D ⁇ 1.0 mm, preferable D ⁇ 1.4 mm, more preferably D ⁇ 2.0 mm.
  • the outwardly shaped first areas 31 and the inwardly shaped second area 32 are shaped like a part of a sphere with a first radius Rl of the sphere of the outwardly shaped first areas 31 and a second radius R2 of the sphere of the inwardly shaped second areas 32, where the first radius Rl is larger than the second radius R2.
  • the second radius R2 may range between 2 mm and 6 mm and a ratio between first radius Rl and second radius R2 ranges between 1.5 and 2.0.
  • the thickness D equals the difference between first and second radius Rl, R2.
  • the substrate 2 can be made of material with a refractory index n > 1.6, preferably n > 1.7, more preferably n > 1.8 (high index material).
  • the light 51 (dashed arrow) is directly through the second area 32, because the angle of incidence at the interface between second area 32 and air is smaller than the critical angle for total reflection.
  • the light 52 (closed arrow) traveling along a light path having an angle of incidence, which leads to a total reflection at the interface between second area 32 and air will impinge on the third area 33 at a more perpendicular angle and will therefore being coupled out to air through the third area 33 in order to contribute to the light 5 emitted from the OLED.
  • An OLED layer according to priot art has typically a luminous efficacy of 35 lm/W achieved on a blank float glass substrate, about 49 lm/W are achieved with an additional out-coupling foil.
  • a luminous efficacy of about 56 lm/W is achieved.
  • high index glass or a high index intermediate layer (index matching layer) below the anode and a substarte with the array of light extraction elements as shown in fig. 3 a luminous efficacy of 74 lm/W can be obtained.
  • the blank light emission can be improved by a factor of about 1,6 in the low n case and by a factor of about 2,1 in the high n case.
  • a further advantage of applying an array of light extraction elements as shown here, is the homogeneous brightness impression when lokking at the second side 22 of the subtrate 2. For each light extraction element 3, there will still be a brighter rim of emission coming from the third area 33 around an emission through the second areas 32 being not as bright as the emission from third areas 33. However, in case of small light extraction elements, people looking at the second side 22 of the substrate 2 will see light 5 with a homogeneous brightness, since the brightness deviation cannot be resolved by the human eye.
  • the electrode of the electroluminescent layer stack 4 arranged on the side of the electroluminescent layer stack 4 facing away from the substrate 2 is made of reflective material, e.g. Al or Ag.
  • the other electrode facing towards the substrate is made of indium-tin-oxide (ITO). Some parts of the anode might remain uncoated for anode contacting. Additional conducting lines made of a highly conductive material may be added to the ITO-electrode to improve the current distribution across the ITO electrode, preferably arranged at the boundaries between adjacent light extraction elements 3 on top of the first area 31. Skilled people will contact the electroluminescent layer stack suitably to a power supply in order to apply the operating voltage to the electroluminescent layer stack. The contacting can be executed by well known techniques from OLEDs and is therefore not shown here. People skilled in the art will chose required encapsulation of the ITO-electrode to improve the current distribution across the ITO electrode, preferably arranged at the boundaries between adjacent light extraction elements 3 on top of the first area 31. Skilled people will contact the electroluminescent layer stack suitably to a power supply in order to apply the operating voltage to the electroluminescent layer stack. The contacting can be executed by well known techniques from O
  • electroluminescent layer stack which are also not shown here.
  • Fig. 4 shows two other embodiments of an OLED according to the present invention with an array of (a) V-shaped light extraction elements, and (b) U-shaped light extraction elements comprising rounded edges in a side view as an alternative to spherically shaped light extraction elements 3.
  • the bowl shape corresponds to a V- or U shape.
  • the effects achieved by the V- or U-shaped light extraction elements 3 are very similar to the effects as being obtained with the substrate 2 as shown in fig.3. All remarks made for fig.3 are also valid for the substrates shown in fig.4.
  • the light 51 (dashed arrow) is directly through the second area 32, because the angle of incidence at the interface between second area 32 and air is smaller than the critical angle for total reflection.
  • the light 52 (closed arrow) traveling along a light path having an angle of incidence, which leads to a total reflection at the interface between second area 32 and air will impinge on the third area 33 at a more perpendicular angle and will therefore being coupled out to air through the third area 33 in order to contribute to the light 5 emitted from the OLED.
  • the U-shaped light extraction elements as shown in fig.4b have the advantage of the presence of rounded edges.
  • the first side 21 of the substrate 2 comprises rounded edges 34 as boundary between adjacent first areas 31 to further improve the ease substrate manufacturing and light out-coupling efficiency and/or the second side 22 comprises rounded edges 34 as boundary between second and third areas 32, 33 improving the deposition quality by avoiding sharp edges.
  • Fig. 5 shows an embodiment of an OLED 1 according to fig.3 additionally comprising an index matching layer 7 (gray).
  • the index matching layer 7 made of a high index material is arranged between the first side 21 of the substrate 2 and the electro lumi- nescent layer stack 4.
  • the index matching layer can be used in case of using substrates with low refractive index and can be used in addition to high index substrates to further improve the refractive index matching between electroluminescent layer stack 4 and substrate 2.
  • Fig. 6 shows an embodiment of an OLED according to the present invention with an array A of circular-shaped light extraction elements 3 in a top view on top of the second side 22 of the substrate 2.
  • the light extraction elements 3 are indicated by dashed squares to indicate the extension of the light extraction elements 3 in an array A.
  • the second areas 32 are circularly shaped as an example. Other shaped are also possible, see previous figures.
  • the third area 33 as one contiguous area separates the second areas 32 from each other.
  • the dashed lines indicating the array A of the extension of the light extraction elements 3 represent a metal grid 8 arranged on the first side 21 of the substrate 2 (here the backside) in electrical contact to the first electrode of the electroluminescent layer stack 4 to distribute the driving current across the entire first side 21 of the substrate 2.
  • the current distribution across a ITO layer as the first electrode may lead to a voltage drop across the ITO layer in case of large sizes of the first electrode.
  • OLEDs with a metal grid 8 provide a higher and more homogeneous brightness.

Landscapes

  • Electroluminescent Light Sources (AREA)

Abstract

L'invention concerne le champ technique des dispositifs électroluminescents organiques avec un couplage en sortie amélioré et un procédé de fabrication de tels DELO. Le dispositif électroluminescent organique (1) comprend un substrat (2) transparent ayant une épaisseur D et comportant un premier côté (21) et un second côté (22) opposé au premier côté (21), le substrat (2) comprenant au moins un élément d'extraction de lumière (3) en forme de cuvette, l'élément d'extraction de lumière (3) comprenant une première zone (31) formée vers l'extérieur et une deuxième zone (32) formée vers l'intérieur opposée à la première zone (31), le premier côté (21) du substrat (2) comprenant la première zone (31) courbée vers l'extérieur de l'élément d'extraction de lumière (3) et le second côté (22) du substrat (2) comprenant la deuxième zone (32) courbée vers l'intérieur de l'élément d'extraction de lumière (3) et une troisième zone (33) séparant au moins la deuxième zone (32) de la première zone (31), un empilement de couches électroluminescentes (4) comprenant au moins une couche électroluminescente organique agencée entre une première et une seconde électrodes étant déposée en haut du premier côté (21) du substrat (2) et la lumière (5) émise par le dispositif électroluminescent organique (1) étant émise à travers le second côté (22) du substrat (2). Dans le cas où on utilise une matrice (A) d'éléments d'extraction de lumière (3), une impression de luminosité homogène peut être obtenue.
PCT/IB2013/055206 2012-07-05 2013-06-25 Dispositif électroluminescent organique WO2014006538A1 (fr)

Applications Claiming Priority (2)

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US201261668109P 2012-07-05 2012-07-05
US61/668,109 2012-07-05

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WO2014006538A1 true WO2014006538A1 (fr) 2014-01-09

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113193135A (zh) * 2020-01-29 2021-07-30 夏普株式会社 发光器件

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1768463A1 (fr) * 2004-05-17 2007-03-28 Zeon Corporation Élément électroluminescent, équipement d'éclairage et dispositif d'affichage
US20100293782A1 (en) * 2009-05-21 2010-11-25 Semiconductor Energy Laboratory Co., Ltd. Method for manufacturing light-emitting device
US20100308359A1 (en) * 2009-06-09 2010-12-09 Sinmat, Inc. High light extraction efficiency solid state light sources
US20120057100A1 (en) 2009-05-18 2012-03-08 Shoichi Masuda Optical members and devices employing the same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1768463A1 (fr) * 2004-05-17 2007-03-28 Zeon Corporation Élément électroluminescent, équipement d'éclairage et dispositif d'affichage
US20120057100A1 (en) 2009-05-18 2012-03-08 Shoichi Masuda Optical members and devices employing the same
US20100293782A1 (en) * 2009-05-21 2010-11-25 Semiconductor Energy Laboratory Co., Ltd. Method for manufacturing light-emitting device
US20100308359A1 (en) * 2009-06-09 2010-12-09 Sinmat, Inc. High light extraction efficiency solid state light sources

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113193135A (zh) * 2020-01-29 2021-07-30 夏普株式会社 发光器件

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