2022PF00494 - 1 – OPTOELECTRONIC COMPONENT DESCRIPTION The present invention relates to an optoelectronic component. This patent application claims the priority of German patent application 102022 120 659.9, the disclosure content of which is hereby incorporated by reference. It is known to provide optoelectronic components having light-emitting semiconductor chips with wavelength converting elements to convert parts of the light emitted by the light- emitting semiconductor chip into light having another wave- length. Light leaving such optoelectronic components can ex- hibit colour-over-angle non-uniformities having a higher fraction of converted light at larger angles. The article “Electromagnetic scattering by magnetic spheres”, Kerker et al., Journal of the Optical Society of America Vol. 73, 765 (1983), describes a number of unusual electromagnetic scattering effects for magnetic spheres. The article “A generalized Kerker condition for highly di- rective nanoantennas”, Alaee et al., Optics Letters Vol. 40, No. 11, 2645, describes a nanoantenna with balanced electric and magnetic dipole moments. The article “Toward Perfect Optical Diffusers: Dielectric Huygens’ Metasurfaces with Critical Positional Disorder”, Arslan et al., Adv. Mater. 2022, 34, 2105868, describes how dielectric Huygens’ metasurfaces can implement wavelength- selective diffusers with negligible absorption losses and nearly Lambertian scattering profiles that are largely inde- pendent of the angle and polarization of incident waves. It is an object of the present invention to provide an optoe- lectronic component. This object is achieved by an optoelec- 2022PF00494 - 2 – tronic component according to claim 1. Various refinements are specified in the dependent claims. An optoelectronic component comprises an optoelectronic semi- conductor chip, a wavelength converting element arranged on the optoelectronic semiconductor chip, and a diffusor element arranged on the wavelength converting element. The diffusor element comprises a plurality of dielectric nanoantennas ar- ranged in a planar configuration. The nanoantennas form a metasurface. The metasurface of this optoelectronic component may improve the colour-over-angle uniformity of the light emitted by this optoelectronic component by redistributing outgoing uncon- verted light. In particular, the dielectric nanoantenna of the diffusor element of this optoelectronic component may re- distribute unconverted light at a near perpendicular incident angle to larger angles of radiation. The diffusor element of this optoelectronic component may al- so help to outcouple light beyond the escape cone. This may improve the efficiency of the optoelectronic component. The diffusor element of this optoelectronic component may furthermore provide a gradual effective index transition for wavelengths larger than that of the light emitted by the op- toelectronic semiconductor chip which results in an anti- reflection effect that improves the efficiency of the optoe- lectronic component. In an embodiment of the optoelectronic component, each nano- antenna comprises a height of less than 500 nm, preferably less than 300 nm. Nanoantennas comprising such a height may be small enough to cause minimal scattering effects for long- er wavelengths but large enough to sustain a strong enough electric and magnetic dipole resonance for unconverted light at near perpendicular incident angles. 2022PF00494 - 3 – In an embodiment of the optoelectronic component, each nano- antenna comprises a diameter of less than 500 nm, preferably less than 300 nm. Nanoantennas comprising such a diameter may be small enough to cause minimal scattering effects for long- er wavelengths but large enough to sustain a strong enough electric and magnetic dipole resonance for unconverted light at near perpendicular incident angles. In an embodiment of the optoelectronic component, an average distance between the nanoantennas is below 600 nm, preferably below 450 nm. Advantageously, this may ensure that the metasurface formed by the nanoantennas scatters minimally at longer wavelengths but strongly for unconverted light. In an embodiment of the optoelectronic component, the nanoan- tennas are arranged in a non-periodical configuration. Advan- tageously, a non-periodical configuration may lead to a more homogeneous angular scattering distribution. In another embodiment of the optoelectronic component, the nanoantennas are arranged in a periodical configuration. Ad- vantageously, a periodical configuration may help to minimize backscattering. In an embodiment of the optoelectronic component, each nano- antenna comprises a shape that is asymmetric between a height direction and a lateral direction. Advantageously, nanoanten- nas having such an asymmetric shape may exhibit a dual re- sponse, fulfilling the Kerker condition. In an embodiment of the optoelectronic component, each nano- antenna comprises a conical shape or a pyramidal shape. Ad- vantageously, nanoantennas comprising a conical shape or a pyramidal shape may provide an improved gradual effective in- dex transition effect within the diffusor element of the op- toelectronic component. 2022PF00494 - 4 – In another embodiment of the optoelectronic component, each nanoantenna comprises a cylindrical shape. Advantageously, a cylindrical shape comprises an asymmetry between the height direction and the lateral direction. Another advantage of a cylindrical shape is that it can be produced easily. In an embodiment of the optoelectronic component, the nanoan- tennas comprise a material having a refractive index of at least 2. Advantageously, nanoantennas comprising such a re- fractive index may provide a strong scattering response. In an embodiment of the optoelectronic component, the nanoan- tennas comprise TiOx or NbOx. Advantageously, these materials provide a sufficiently large refractive index. In an embodiment of the optoelectronic component, the nanoan- tennas are distanced from the wavelength converting element by less than 200 nm, preferably by less than 100 nm. Advanta- geously, the nanoantennas are placed in the near-field range of the surface of the wavelength converting element in this case. This may help the diffusor element to improve outcou- pling of light from the wavelength converting element by ex- tracting light outside of the escape cone via scattering. In an embodiment of the optoelectronic component, the nanoan- tennas are embedded in a dielectric multilayer stack. A die- lectric multilayer stack may form a distributed Bragg reflec- tor (DBR). The dielectric multilayer stack may help to fur- ther improve outcoupling of converted light from the wave- length converting element. In an embodiment of the optoelectronic component, the dielec- tric multilayer stack is designed to cause constructive in- terference in the region of the nanoantennas for unconverted light striking at a perpendicular incident angle. This may help to provide a stronger scattering effect for unconverted light by enhancing the field in the region of the metasurface formed by the nanoantennas. 2022PF00494 - 5 – In an embodiment of the optoelectronic component, the nanoan- tennas are embedded in a dielectric layer having a refractive index different from that of the material of the nanoanten- nas. Advantageously, this results in an index contrast be- tween the nanoantennas and the embedding dielectric layer which allow the nanoantennas to provide a scattering effect. In an embodiment of the optoelectronic component, the nanoan- tennas are embedded in a dielectric layer comprising SiO2, AlOx, NbOx, or MgF2. Advantageously, a dielectric layer com- prising these materials may comprise a refractive index dif- ferent from that of the nanoantennas. In an embodiment of the optoelectronic component, the optoe- lectronic semiconductor chip is designed to emit light in the blue spectral range. Advantageously, light in the blue spec- tral range can be converted to other visible wavelengths which may allow the optoelectronic component to create white light. The above-described properties, features and advantages of this invention, and the way in which they are achieved, will become more clearly and readily comprehensible in conjunction with the following description of the exemplary embodiments, which will be explained in more detail in connection with the drawings, in which, respectively in a schematized representa- tion, Fig. 1 shows a sectional drawing of a first variant of an op- toelectronic component; Fig. 2 shows a nanoantenna comprising a cylindrical shape; Fig. 3 shows a nanoantenna comprising a conical shape; Fig. 4 shows a nanoantenna comprising a pyramidal shape; 2022PF00494 - 6 – Fig. 5 shows a non-periodical configuration of nanoantennas; Fig. 6 shows a periodical configuration of nanoantennas; Fig. 7 shows a sectional view of a second variant of an opto- electronic component; and Fig. 8 shows a sectional drawing of a third variant of an op- toelectronic component. Fig. 1 shows a schematic sectional view of a first variant of an optoelectronic component 10. The optoelectronic component 10 is designed to emit light, for example visible light hav- ing a white colour. The optoelectronic component 10 comprises an optoelectronic semiconductor chip 100 having an upper side 101 and a lower side 102 which is opposed to the upper side 101. The optoe- lectronic semiconductor chip 100 may be a light-emitting di- ode chip, for example. The optoelectronic semiconductor chip 100 is designed to emit light at its upper side 101. The op- toelectronic semiconductor chip 100 may be designed to emit light in the blue spectral range, for example. The optoelectronic component 10 furthermore comprises a wave- length converting element 200 having an upper side 201 and a lower side 202 which is opposed to the upper side 201. The wavelength converting element 200 is arranged on the upper side 101 of the optoelectronic semiconductor chip 100 such that the lower side 202 of the wavelength converting element 200 faces the upper side 101 of the optoelectronic semicon- ductor chip 100. The wavelength converting element 200 is de- signed to convert parts of the light emitted by the optoelec- tronic semiconductor chip 100 into light having another wave- length. The wavelength converting element 200 may be designed to convert blue light emitted by the optoelectronic semicon- ductor chip 100 into yellow or red light, for example. The wavelength converting element 200 may be designed such that a 2022PF00494 - 7 – mixture of unconverted light emitted by the optoelectronic semiconductor chip 100 and light converted by the wavelength converting element 200 gives the impression of having a white colour. The optoelectronic component 10 furthermore comprises a dif- fusor element 300 having an upper side 301 and a lower side 202 which is opposed to the upper side 201. The diffusor ele- ment 300 is arranged on the upper side 201 of the wavelength converting element 200 such that the lower side 302 of the diffusor element 300 faces the upper side 201 of the wave- length converting element 200. The diffusor element 300 comprises a plurality of dielectric nanoantennas 400. The dielectric nanoantennas 400 are ar- ranged next to each other in a planar configuration in a plane 320 that is parallel to the upper side 201 of the wave- length converting element 200. Together, the dielectric nano- antennas 400 form a metasurface 310. Each nanoantenna 400 comprises a height 410 measured in a height direction 330 that is perpendicular to the plane 320 and a diameter 420 measured in a lateral direction 340 that is parallel to the plane 320. Neighbouring nanoantennas 400 comprise a distance 430 which may vary over different parts of the metasurface 310 formed by the nanoantennas 400. The diffusor element 300 having the metasurface 310 formed by the plurality of nanoantennas 400 may help to improve a col- our-over-angle uniformity of the light radiated by the optoe- lectronic component 10. To this end, the metasurface 310 may scatter unconverted light emitted by the optoelectronic semi- conductor chip 100 which reaches the upper side 201 of the wavelength converting element 200 at a small (near perpendic- ular) incident angle 120 to a broader range of radiation an- gles 110 in the forward direction. The metasurface thus re- distributes the unconverted light having a small incident an- gle 120 to have a more favourable angular distribution. Un- 2022PF00494 - 8 – converted light reaching the metasurface 310 at small inci- dent angles 120 undergoes only minimal backscattering. Light converted by the wavelength converting element 200 un- dergoes only minimal scattering in the metasurface 310. The diffusor element 300 may have a high transmittance for a broad range of incident angles 120. For example, the diffusor element 300 may have a transmittance of larger than 80% or a transmittance of larger than 90% or a transmittance of close to 100% for all incident angles 120. The diffusor element 300 may have a high transmittance for a broad range of wavelengths. For example, the diffusor element 300 may have a transmittance of larger than 80% or a trans- mittance of larger than 90% or a transmittance of close to 100% for both the wavelengths of unconverted light and con- verted light. In order to scatter unconverted light but cause a minimal scattering for converted light, the nanoantennas 400 have to be small enough to cause minimal scattering effects for wave- lengths larger than those of the unconverted light but large enough to sustain a strong enough electric and magnetic di- pole resonance for unconverted light at near normal incident angles 120. When the unconverted light is in the blue spec- tral range, it is convenient if the height 410 of each nano- antenna 400 is less than 500 nm or even less than 300 nm. It is also convenient if the diameter 420 of each nanoantenna 400 is less than 500 nm or even less than 300 nm. The average distance 430 between neighbouring nanoantennas 400 may be be- low 600 nm or even below 450 nm to ensure that the metasur- face 310 scatters minimally at longer wavelengths but strong- ly for unconverted light. The individual nanoantennas 400 may fulfil the Kerker condi- tion and provides a close to dual response with a spectral overlap of electric and magnetic dipolar or even multipolar 2022PF00494 - 9 – resonances. To this end, the nanoantennas 400 may each com- prise a shape that is asymmetric between the height direction 330 and the lateral direction 340. Fig. 2 shows a schematic perspective view of a nanoantenna 400 having a cylindrical shape 500 with a longitudinal axis that is parallel to the height direction 330. Fig. 3 shows a schematic perspective view of a nanoantenna 400 having a con- ical shape 510 with a longitudinal axis that is parallel to the height direction 330. In the examples of Fig. 2 and 3, the base shape of the cylindrical shape 500 and the conical shape 510 is a circle. However, other shapes may be used as the base as well. Fig. 4 shows a schematic perspective view of a nanoantenna 400 comprising a pyramidal shape 520 with a height axis that is parallel to the height direction 330. The pyramidal shape 520 comprises a square base in the example of Fig. 4 but may also comprise a different polygonal shape as its base. The nanoantennas 400 of the diffusor element 300 of the opto- electronic component 10 may comprise cylindrical shapes 500, conical shapes 510, pyramidal shapes 520 or other shapes. It is convenient if all nanoantennas 400 forming the metasurface 310 of the diffusor element 300 comprise similar shapes or the same shape. In the lateral direction 340 of the plane 320, the nanoanten- nas 400 may be arranged in a non-periodical configuration 600 as schematically shown in Fig. 5 or in a periodical configu- ration 610 as schematically shown in Fig. 6. The non- periodical configuration 600 may be a perturbed configura- tion, a soft-core uniform configuration, a hard-core uniform configuration or another non-periodical configuration. A soft-core uniform or a hard-core uniform configuration may allow for a more homogeneous or Lambertian-like angular scat- tering distribution. A periodical configuration 610 or a per- turbed configuration may lead to reduced backscattering. 2022PF00494 - 10 – It is convenient if the nanoantennas 400 comprise a material having a high refractive index, in particular a refractive index of at least 2. The nanoantennas 400 may comprise TiOx or NbOx, for example. The diffusor element 300 of the optoelectronic component 10 may also support outcoupling of unconverted light at large incident angles 120 which are beyond the escape cone and which would normally not be able to leave the wavelength con- verting element 200 at its upper side 201. Due to an in- creased prominence of first order diffraction scattering, such light may be outcoupled at oblique radiation angles 110 in the angular region around the edge of the escape cone. In order to achieve this effect, the plane 320 of the metasurface 310 should be placed close to the upper side 201 of the wavelength converting element 200 such that the metasurface 310 is placed within the wave-optical near-field region of the upper side 201 of the wavelength converting el- ement 200. This may be the case in the variant of the optoe- lectronic component 10 depicted in Fig. 1, where the nanoan- tennas 400 are placed directly on the upper side 201 of the wavelength converting element 200 such that the plane 320 of the metasurface 310 is very close or identical to the upper side 201 of the wavelength converting element 200. In gen- eral, in order to achieve said effect, it is convenient if the nanoantennas 400 are distanced from the wavelength con- verting element 200 by less than 200 nm or even by less than 100 nm. A third effect that may be achieved by the diffusor element 300 of the optoelectronic component 10 is an improved outcou- pling of converted light at the upper side 201 of the wave- length converting element 200 due to anti-reflection effects caused by the metasurface 310 formed by the nanoantennas 400 acting as a gradual effective index transition region. A gradual effective index transition may for example be 2022PF00494 - 11 – achieved if the nanoantennas 400 comprise a conical shape 510 or a pyramidal shape 520 as illustrated in Figs. 3 and 4. Fig. 7 shows a schematic sectional drawing of a second vari- ant of the optoelectronic component 10. The variant depicted in Fig. 7 is similar to that of Fig. 1. In the following, on- ly the differences between the variant of Fig. 7 and that of Fig. 1 will be explained. Otherwise, the preceding descrip- tion of the variant of Fig. 1 is also valid for the variant of the optoelectronic component 10 depicted in Fig. 7. In Fig. 7, the diffusor element 300 of the optoelectronic component 10 comprises a dielectric multilayer stack 700. The dielectric multilayer stack comprises several layers of dif- ferent dielectric materials arranged on top of each other. The dielectric multilayer stack 700 may form a distributed Bragg reflector (DBR). The nanoantennas 400 forming the metasurface 310 of the dif- fusor element 300 are embedded in an embedding layer 710 of the dielectric multilayer stack 700. It is convenient if the material of the embedding layer 710 is chosen such that there is a large difference between the refractive index of the nanoantennas 400 and that of the material of the embedding layer 710. The embedding layer 710 may comprise SiO2, AlOx, NbOx, or MgF2, for example. The dielectric multilayer stack 700 may act as a resonant cavity that produces constructive interference in the region of the metasurface 310 when unconverted light impinges on the diffusor element 300 at a small incident angle 120. This may improve the angular redistribution of the unconverted light achieved by the metasurface 310 of the diffusor element 300. The dielectric multilayer stack 700 of the diffusor element 300 may cause the metasurface 310 to be placed at a distance 350 from the upper side 201 of the wavelength converting ele- ment 200. The distance 350 may be less than 200 nm or even 2022PF00494 - 12 – less than 100 nm such that the metasurface 310 is placed in the near-field range of the upper side 201 of the wavelength converting element 200. In other variants, the distance 350 is larger than 200 nm. Fig. 8 shows a schematic sectional view of a third variant of the optoelectronic component 10. The variant of Fig. 8 is similar to that of Fig. 1. In the following, only the differ- ences between the variant of Fig. 10 and the variant of Fig. 1 will be explained. Otherwise, the description of the vari- ant of the optoelectronic component 10 depicted in Fig. 1 is also valid for the variant shown in Fig. 8. In Fig. 8, the optoelectronic component 10 comprises a spacer 800 arranged between the upper side 201 of the wavelength converting element 200 and the lower side 302 of the diffusor element 300. Due to the spacer 800, the metasurface 310 is separated from the upper side 201 of the wavelength convert- ing element 200 by the distance 350. The distance 350 may be smaller than 200 nm or even smaller than 100 nm such that the metasurface 310 is placed in the near-field range of the up- per side 201 of the wavelength converting element 200. The distance 350 may be larger than 200 nm in other variants. The spacer 800 may comprise a glass for example. In Fig. 8, the nanoantennas 400 are embedded in an embedding material 810 arranged on the spacer 800. The embedding mate- rial 810 may protect the nanoantennas 400 from external in- fluences. It is convenient if the embedding material 810 has a refractive index different from that of the material of the nanoantennas 400. The embedding material 810 may comprise SiO2, AlOx, NbOx, or MgF2, for example. The embedding material 810 may be omitted such that the nanoantennas 400 are exposed to air as in the variant shown in Fig. 1. In another variant of the optoelectronic component 10, the nanoantennas 400 forming the metasurface 310 are arranged on the upper side 201 of the wavelength converting element 200 2022PF00494 - 13 – as in the variant shown in Fig. 1, but are embedded in an em- bedding material 810 as in the variant of Fig. 8. In another variant of the optoelectronic component 10, the diffusor element 300 comprises a dielectric multilayer stack 700 as in the variant of Fig. 7. The nanoantennas 400 are em- bedded in the dielectric multilayer stack 700. A spacer 800 is arranged between the upper side 201 of the wavelength con- verting element 200 and the lower side 302 of the diffusor element 300 as in the variant shown in Fig. 8. The invention has been illustrated and described in greater detail on the basis of the preferred exemplary embodiments. However, other variations may be derived therefrom by a per- son skilled in the art.

2022PF00494 - 14 – REFERENCE SYMBOLS 10 optoelectronic component 100 optoelectronic semiconductor chip 101 upper side 102 lower side 110 radiation angle 120 incident angle 200 wavelength converting element 201 upper side 202 lower side 300 diffusor element 301 upper side 302 lower side 310 metasurface 320 plane 330 height direction 340 lateral direction 350 distance 400 nanoantenna 410 height 420 diameter 430 distance 500 cylindrical shape 510 conical shape 520 pyramidal shape 600 non-periodical configuration 610 periodical configuration 700 dielectric multilayer stack 2022PF00494 - 15 – 710 embedding layer 800 spacer 810 embedding layer