Light-Emitting Device and Method for Producing a Light-Emitting Device

Abstract

A light-emitting device includes a light-emitting semiconductor component that emits first light in a first wavelength range during operation A wavelength conversion element converts the first light at least partly into second light in a second wavelength range is arranged in the beam path of the first light. The second wavelength range differs from the first wavelength range. The wavelength conversion element includes nanoparticles containing organic luminescent molecules in a basic material formed from an SiO2-based material. A method for producing a light-emitting device is furthermore specified.

Claims

1-20. (canceled)

21. A light-emitting device, comprising: a light-emitting semiconductor component that radiates first light in a first wavelength range during operation; and a wavelength conversion element arranged in a beam path of the first light, wherein the wavelength conversion element is configured to convert the first light at least partially into second light in a second wavelength range different from the first wavelength range, the wavelength conversion element comprising nanoparticles containing organic luminescent molecules in an SiO.sub.2-based basic material.

22. The device according to claim 21, wherein the nanoparticles comprise a coating on the basic material.

23. The device according to claim 22, wherein the coating has physical properties that prevent a particle aggregation, increase pourability of the particles, change a refractive index of the nanoparticles, or serve as a wavelength filter.

24. The device according to claim 21, wherein the wavelength conversion element comprises a matrix material, the nanoparticles being arranged in the matrix material.

25. The device according to claim 24, wherein the wavelength conversion element comprises, in the matrix material, fillers having physical properties that prevent a particle aggregation, increase pourability of the particles, change a refractive index of the nanoparticles, or serve as a wavelength filter.

26. The device according to claim 21, wherein the wavelength conversion element further comprises scattering particles.

27. The device according to claim 21, wherein at least some nanoparticles contain a plurality of different organic luminescent molecules.

28. The device according to claim 21, wherein multiple different particle groups are present in the wavelength conversion element, each particle group being formed by nanoparticles that contain the same organic luminescent molecules.

29. The device according to claim 28, wherein different particle groups are arranged spatially separated in the wavelength conversion element.

30. The device according to claim 21, wherein the organic luminescent molecules comprise one or more materials selected from the group consisting of: acridine dyes, acridinone dyes, anthraquino dyes, anthracene dyes, cyanine dyes, dansyl dyes, squaryllium dyes, spiropyrans, boron-dipyrromethenes, perylenes, pyrenes, naphthalenes, flavins, pyrroles, porphyrins and metal complexes thereof, diarylmethane dyes, triarylmethane dyes, nitro and nitroso dyes, phthalocyanine dyes and metal complexes of phthalocyanines, quinones, azo dyes, indophenol dyes, oxazines, oxazones, thiazines and thiazoles, fluorenes, flurones, pyronines, rhodamines, coumarins.

31. The device according to claim 21, wherein the organic luminescent molecules comprise transition metal complexes with organic ligands; the transition metals comprise metals selected from the group consisting of Rh, Os, Ru, Ir, Pd, and Pt; and the organic ligands comprise one or more materials derived from basic matrices selected from the group consisting of: porphyrins, porphines, 2,2-bipyridines, 2-phenylpyridines, 3-(thiazole-2-yl), 3-(benzothiazole-2-yl), 3-(imidazole-2-yl), 3-(benzimidazole-2-yl), pyridyl azolate.

32. The device according to claim 21, wherein the nanoparticles comprise anchor molecule chains so that the nanoparticles bind to preselected chemical surfaces in a chemical and selective manner.

33. The device according to claim 21, wherein the wavelength conversion element comprises further inorganic wavelength conversion substances in addition to the nanoparticles.

34. The device according to claim 21, wherein the light-emitting semiconductor component comprises an inorganic light-emitting diode.

35. The device according to claim 21, wherein the light-emitting semiconductor component comprises an organic light-emitting diode.

36. A method for producing a light-emitting device, the method comprising: providing a light-emitting semiconductor component that radiates first light in a first wavelength range during operation; and applying a wavelength conversion element in adjacent a beam path of the first light; wherein the wavelength conversion element is configured to convert the first light at least partially into second light in a second wavelength range different from the first wavelength range; wherein the wavelength conversion element comprises nanoparticles containing organic luminescent molecules in an SiO.sub.2-based basic material; and wherein the nanoparticles are applied by at least one or a combination of the following application methods: dispensing, spraying, printing, electrophoresis, electro-spraying, and applying a pre-manufactured wavelength conversion element with the nanoparticles.

37. The method according to claim 36, wherein applying the wavelength conversion element comprises applying the nanoparticles in a solvent, the method further comprising removing the solvent after applying the nanoparticles.

38. The method according to claim 36, wherein applying the wavelength conversion element comprises applying the nanoparticles together with a matrix material.

39. The method according to claim 36, further comprising applying a matrix material to the nanoparticles after applying the wavelength conversion element.

40. The method according to claim 36, wherein the wavelength conversion element having the nanoparticles is pre-manufactured by a printing process or a molding process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Other advantages, advantageous embodiments and further developments are indicated in the exemplary embodiments described in conjunction with the figures.

[0069] The figures show:

[0070] FIG. 1 a light-emitting device according to an exemplary embodiment;

[0071] FIGS. 2 to 4 nanoparticles according to further exemplary embodiments; and

[0072] FIGS. 5 and 6 light-emitting devices according to further exemplary embodiments.

[0073] Throughout the exemplary embodiments, same, similar or equivalent elements may in each case be indicated with the same reference numerals. The elements shown and their size ratios are not to be considered as true to scale, rather, individual elements such as layers, components, elements and areas may be illustrated in an exaggerated size for the purpose of a better understanding.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0074] FIG. 1 shows a light-emitting device 100 which comprises a light-emitting semiconductor component 1 radiating first light in a first wavelength range during operation. A wavelength conversion element 2 is arranged in the beam path of the first light, which converts the first light at least partially into a second light in a second wavelength range different from the first wavelength range.

[0075] The light-emitting semiconductor component 1 may be a semiconductor component emitting inorganic light, for example. For example, the semiconductor component emitting inorganic light may comprise or consist of an inorganic light-emitting diode. The inorganic light-emitting diode may comprise a light-emitting semiconductor chip comprising at least one active layer for generating the first light. Depending on the desired wavelength to be radiated, the light-emitting semiconductor chip may be produced on the basis of different semiconductor material systems. For visible short-wave light, i.e. in particular blue or green light and/or ultraviolet light, a semiconductor layer sequence on the basis of In.sub.xGa.sub.yAl.sub.1-x-yN is particularly suitable, with 0x1 and 0y1. For green to red light, the semiconductor layer sequence may for example comprise In.sub.xAl.sub.yGa.sub.1-x-yP with 0x1, 0y1 and x+y1, while AlGsAs-based semiconductor material is suitable to produce light in a red to infrared wavelength range, for example.

[0076] The light-emitting semiconductor component may particularly comprise or consist of a semiconductor layer sequence, particularly preferably an epitaxially-grown semiconductor layer sequence. To that end, the semiconductor layer sequence may be grown on the growth substrate by means of an epitaxy method, metalorganic vapor phase deposition (MOVPE) or molecular beam epitaxy (MBE) and be provided with electric contacts. By singulating the growth substrate having the semiconductor layer sequence grown thereon, a plurality of light-emitting semiconductor chips can be provided. Furthermore, the semiconductor layer sequence can be transferred to the substrate prior to singularization and the growth substrate may be thinned or completely removed. Such semiconductor chips, comprising a carrier substrate instead of the growth substrate, may also be referred to as so-called thin-film semiconductor chips.

[0077] A thin-film semiconductor chip is in particular characterized by the following characteristic features:

[0078] a reflective layer is applied or formed on a first main surface of a radiation-generating epitaxial layer sequence facing the carrier substrate, the layer reflecting at least part of the electromagnetic radiation generated in the epitaxial layer sequence back into the epitaxial layer sequence,

[0079] the epitaxial layer sequence has a thickness of approximately 20 m or less, in particular between 4 m and 10 m; and

[0080] the epitaxial layer sequence includes at least one semiconductor layer with at least one surface having an intermixing structure, which in the ideal case leads to an approximately even ergodic distribution of the light in the epitaxial epitaxial layer sequence, i.e. it presents a possible ergodic, stochastic scattering behavior.

[0081] A thin film semiconductor chip in good approximation is a Lambert surface radiator. The basic principle of a thin film light diode chip is, for example, described in document I. Schnitzer et al., Appl. Phys. Lett. 63 (16) 18 Oct. 1993, 2174-2176.

[0082] The semiconductor layer sequence may comprise a conventional p-n-junction, a double hetero-structure, a single quantum well (SQW) structure or a multi-quantum well (MQW) structure. Besides the active region, the semiconductor layer sequence may comprise further functional layers and functional regions, such as p- and/or n-junction-doped functional charge carrier transport layers, i.e. electron or hole transport layers, un-doped or n-doped or p-doped confinement, cladding and waveguide layers, barrier layers, planarization layers, buffer layers, protection layers and/or electrodes as well as combinations thereof.

[0083] Additionally, or as an alternative, the light-emitting semiconductor component 1 may as well comprise or consist of an organic light-emitting semiconductor component, such an organic light-emitting diode (OLED). Referring to the principle structure of an organic light-emitting semiconductor component, reference is made to WO 2010/066245 A1, which is expressively incorporated herein by reference as concerning the structure of an organic light-emitting semiconductor component.

[0084] The wavelength conversion element 2 comprises a plurality of nanoparticles 3. In the exemplary embodiment shown, the nanoparticles 3 are arranged in a matrix material 4. As an alternative thereto, the nanoparticles 3 may as well form the wavelength conversion element 2 without the matrix material 4 and be arranged in the beam path of the first light of the light-emitting semiconductor component 1. As an alternative to the shown uniform distribution of nanoparticles 3 in the matrix material 4, these nanoparticles may as well be arranged in the matrix material 4 in a spatial manner.

[0085] As shown in FIG. 1, the wavelength conversion element 2 may be arranged directly on the light-emitting semiconductor component 1. The wavelength conversion element 2 may be arranged directly on one or more of the surfaces of the light-emitting semiconductor component 1 to that end. As an alternative, a so-called remote arrangement is possible as well, in which the wavelength conversion element 2 may be arranged at a distance of the light-emitting semiconductor component 1. To this end, other materials, in the form of layers or a potting of the light-emitting semiconductor component 1, for example, may be arranged between the light-emitting semiconductor component 1 and the wavelength conversion element 2. Furthermore, it is possible for a gas such as light to be present between the light-emitting semiconductor component 1 and the wavelength conversion element 2. The light-emitting device 100 may further comprise a housing, for example, in which the light-emitting semiconductor component 1 and the wavelength conversion element 2 are arranged (not shown).

[0086] The matrix material 4 may be a silicone or epoxy resin intermixed with nanoparticles 3, for example. As an alternative, the matrix material 4 may also comprise one or more of the materials mentioned above in the general section.

[0087] The nanoparticles 3 are explained in detail, here and in the following, in conjunction with FIGS. 2 to 4, in which exemplary embodiments for nanoparticles are shown.

[0088] FIG. 2 shows a nanoparticle 3 which comprises a basic substrate 30 containing organic luminescent molecules 31. In particular, the organic luminescent molecules 31 are enclosed by the basic material 30 so that nanoparticle 3 comprises the molecules 31 inside thereof. The basic material 30 is preferably formed of photo-physically inert material, particularly preferably a glass-like material. In the exemplary embodiment shown, the basic material 30 is formed by a SiO2-based material containing the organic luminescent molecules 31. The SiO2-based material thus forms a matrix, in which the organic luminescent molecules 31 are enclosed and contained. By this, the organic luminescent molecules 31 are encapsulated from the environment and protected against degradation processes, the reaction with surrounding gas or the matrix material.

[0089] The organic luminescent molecules 31 may comprise pure organic molecules as well as organic molecules having metal atoms, in particular transition metal complexes with organic ligands. Without limiting the subject-matter described herein, reference is made to the following particularly preferred materials. [0090] perylene imides [0091] parylene carboxylates [0092] transition metal complexes having transition metals, selected from Os(III), Ru(III), Ir(III), Pt(III), and organic ligands, selected from one or more of the following materials, which are derived from the following basic matrices: porphyrins, porphines, 2,2-bipyridines, 2-phenylpyridines, 3-(thiazole-2-yl), 3-(Benzothiazole-2-yl), 3-(Imidazole-2-yl), 3-(benzimidazole-2-yl), pyridyl azolates.

[0093] The organic luminescent molecules 31 may additionally or alternatively comprise one or more of the further materials mentioned above in the general section.

[0094] In addition to the organic luminescent molecules 31, further materials may be contained in the basic material 30, for example one or more selected from the following materials: alkaline metals, alkaline earth-metals, halogens, Al, Zr, Hf, Ge, Sn, Pb, B, In, Ga, N, C, P, Ti, Sc, Y, As, Sb, S, Se, H, deuterium. The additional materials and elements, respectively, preferably have a content of less than 5% and particularly preferred of less than 1% in the basic material 30, i.e. in particular in the SiO.sub.2-based material, concerning the weight of the nanoparticles 3. Furthermore, semiconductor nanoparticles can be introduced in the SiO.sub.2 material 30, for example.

[0095] In the light-emitting device 100 shown in FIG. 1, for example, the nanoparticles 3 may be present in a specially-selected size distribution in the wavelength conversion element 2. For example, the nanoparticles 3 may have a size ranging from greater than or equal to 1 nm and less than or equal to 1000 nm. In particular, the sizes range from greater than or equal to 1 nm or less than or equal to 100 nm or greater than or equal to 10 nm or greater than or equal to 50 nm are preferred. As an alternative, the nanoparticles 3 may also have other sizes mentioned above in the general section.

[0096] Depending on the application, the nanoparticles 3 may include only one sort of organic luminescent materials 31. Furthermore, it is as well possible for the nanoparticles 3 to contain a mix of multiple of the organic luminescent materials 31. The organic luminescent molecules may in particular be formed as described above in the general section and accordingly comprise the above-described features.

[0097] FIG. 3 shows another exemplary embodiment for a nanoparticle 3, which additionally comprises a coating 32 around the SiO.sub.2-based material 30, enclosing the nanoparticle 3. The coating 32 may be formed of an inorganic material, such as Al.sub.2O.sub.3, for example. Furthermore, it is also possible, to use an organic coating 32. The organic coating 32 may in particular have the following features: It can prevent a particle aggregation, for example, in a matrix material. Furthermore, the coating may lead to a change of the refractive index of the wavelength conversion element or may as well serve as a wavelength filter. This enables filtering short-wave excitation light, i.e. first light of the light-emitting component, in order to prevent a chemical decomposition of the organic luminescent molecules and/or absorb certain emission areas of the wavelength conversion substance in order to make the spectrum of the second light more narrow-banded.

[0098] FIG. 4 shows another exemplary embodiment for a nanoparticle 3, comprising anchor molecule chains 33 on its surface. The molecule chains may be provided to bind the nanoparticles 3 to certain chemical surfaces in a chemical and selective manner. If suitable anchor molecule chains 33 and surfaces are used, for example in the light-emitting semiconductor component, monolayers of nanoparticles can be produced on the respective surfaces in a self-limiting process. Anchor molecule chains with methoxy or ethoxy groups may be used, for example, as described above in the general section. As an alternative or in addition, other anchor molecule chains, described above in the general section, can be used, which may allow binding to the surface materials described in the general section above.

[0099] For producing the light-emitting device 100 according to FIG. 1, the nanoparticles 3 may, for example, be applied in a formulation with the matrix material 4 into the light path of the light-emitting semiconductor component 1 by a dispensing method, by spraying, or a printing method. Furthermore, it is as well possible to introduce the nanoparticles 3 in an electrical voltage field by electrophoresis or electro spray-coating into the light path of the light-emitting semiconductor component 1. After application of the nanoparticles 3, the particles can optionally be provided with another matrix material, provided that they have already been applied together with a matrix material 4. Furthermore, it is as well possible to apply the nanoparticles 3 in a volatile solvent which is subsequently removed by means of evaporation, for example. By means of application in an electric voltage field or by use of a solvent, it may in particular just as well be possible to apply the nanoparticles without a matrix material.

[0100] Furthermore, it is also possible to pre-manufacture the wavelength conversion element 2, for example, and then apply it in the light path of the light-emitting semiconductor component 1 as a pre-manufactured conversion element. A pre-manufactured wavelength conversion element may for example be produced by a printing process or a forming process, for example by injection molding, compression molding, transfer molding or foil-assisted transfer molding.

[0101] FIG. 5 shows a light-emitting device 101 according to another exemplary embodiment, which, when compared to the light-emitting device 100, comprises scattering particles 5 in addition to the nanoparticles 5. The particles may for example be formed by a colorless, i.e. only light-scattering material as for example TiO2, Al2O3, or glass particles. By adding additional scattering particles 5, the radiation profile and the conversion degree of the wavelength conversion element 2 can be adjusted and optimized independent from another.

[0102] Alternatively or additionally, the wavelength conversion element 2 may contain other fillers which, for example, prevent aggregation of the nanoparticles 3, change the refractive index or serve as a wavelength filter.

[0103] Alternatively or additionally, it is as well possible for the wavelength conversion element 2 to contain other materials as conversion materials besides the nanoparticles 3 as a material for light conversion. For example, inorganic wavelength conversion substances such as the phosphors described above in the general section can be included in the wavelength conversion element 2 in addition to the nanoparticles 3.

[0104] FIG. 6 shows a light-emitting device 102 according to a further exemplary embodiment which, compared to the light-emitting devices 100 and 101 of FIGS. 1 and 5, comprises a light-emitting semiconductor component 1 comprising separately controllable segments 11, 12, 13. The segment may be configured as segments of a semiconductor structure produced in a monolithic way and can be electrically contacted separately from one another, for example. Accordingly, the wavelength conversion element 2 is divided into segments 21, 22, 23 arranged on the segments 11, 12, 13 of the light-emitting semiconductor component 1. The segments 21, 22, 23 contain in each case a particle group with nanoparticles 3, being identical within the groups, while the particle groups are configured differently to one another and comprise nanoparticles 3 with different organic luminescent materials. By this is allowed for the segments 21, 22, 23 to radiate second light differently from one another, such that together with the segmented light-emitting component 102, a multicolored display, for example a RGB-micro display, can be realized.

[0105] According to other exemplary embodiments, the features described in the exemplary embodiments can be combined with one another even if such combinations are not explicitly shown in the figures. Furthermore, the exemplary embodiments described in the figures may comprise additional or alternative features according to the general description.

[0106] The invention is not limited by the description with reference to the exemplary embodiments. The invention rather comprises any new feature as well as any combination of features, particularly including any combination of features in the patent claims, even if the feature or the combination per se is not explicitly indicated in the patent claims or the exemplary embodiments.