Multicolor display apparatus

1. A display apparatus, comprising:

a backlight unit; and

at least one color conversion layer,

said at least one color conversion layer comprising at least one light emitting material comprising at least one composite particle surrounded partially or totally by at least one surrounding medium,

wherein said at least one light emitting material is configured to emit a secondary light in response to an excitation and the at least one composite particle comprises a plurality of nanoparticles encapsulated in an inorganic material,

wherein said inorganic material has a difference of refractive index compared to the at least one surrounding medium superior or equal to 0.02 at 450 nm,

wherein the plurality of nanoparticles comprises at least 1% of semiconductor nanoplatelets,

wherein a loading charge of the nanoparticles in the at least one composite particle is at least 10%, said loading charge being a mass ratio between a mass of the nanoparticles comprised in the at least one composite particle and a mass of the at least one composite particle, and

wherein the backlight unit comprises a light source configured to provide an excitation to the at least one light emitting material.

2. The display apparatus according to claim 1 , wherein the at least one color conversion layer comprises an array of light emitting material forming an array of pixels.

3. The display apparatus according to claim 1 , wherein the inorganic material limits or prevents the diffusion of outer molecular species or fluids into said inorganic material.

4. The display apparatus according to claim 1 , wherein the at least one composite particle in the at least one surrounding medium is configured to scatter light.

5. The display apparatus according to claim 1 , wherein the color conversion layer absorbs at least 70% of incident light on a thickness less or equal to 5 μm, wherein the incident light has a wavelength ranging from 370 to 470 nm.

6. The display apparatus according to claim 1 , wherein the nanoparticles comprised in the at least one composite particle are semiconductor nanocrystals comprising a material of formula MxNyEzAw, wherein: M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; N is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; E is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; A is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; and x, y, z and w are independently a decimal number from 0 to 5; x, y, z and w are not simultaneously equal to 0; x and y are not simultaneously equal to 0; z and w may not be simultaneously equal to 0.

7. The display apparatus according to claim 1 , wherein the at least one surrounding medium is optically transparent.

8. The display apparatus according to claim 1 , wherein the at least one surrounding medium has a thermal conductivity at standard conditions of at least 0.1 W/(m·K).

9. The display apparatus according to claim 6 , wherein the semiconductor nanocrystals comprise at least one shell comprising a material of formula MxNyEzAw, wherein: M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; N is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; E is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; A is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; and x, y, z and w are independently a decimal number from 0 to 5; x, y, z and w are not simultaneously equal to 0; x and y are not simultaneously equal to 0; z and w may not be simultaneously equal to 0.

10. The display apparatus according to claim 6 , wherein the semiconductor nanocrystals comprise at least one crown comprising a material of formula MxNyEzAw, wherein: M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; N is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; E is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; A is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; and x, y, z and w are independently a decimal number from 0 to 5; x, y, z and w are not simultaneously equal to 0; x and y are not simultaneously equal to 0; z and w may not be simultaneously equal to 0.

11. The display apparatus according to claim 6 , wherein the semiconductor nanocrystals comprise 100% of semiconductor nanoplatelets.

12. A display apparatus, comprising:

an array of light sources; and

at least one color conversion layer,

said at least one color conversion layer comprising at least one light emitting material comprising at least one composite particle surrounded partially or totally by at least one surrounding medium,

wherein said at least one light emitting material is configured to emit a secondary light in response to an excitation and the at least one composite particle comprises a plurality of nanoparticles encapsulated in an inorganic material,

wherein said inorganic material has a difference of refractive index compared to the at least one surrounding medium superior or equal to 0.02 at 450 nm,

wherein the plurality of nanoparticles comprises at least 1% of semiconductor nanoplatelets,

wherein a loading charge of the nanoparticles in the at least one composite particle is at least 10%, said loading charge being a mass ratio between a mass of the nanoparticles comprised in the at least one composite particle and a mass of the at least one composite particle, and

wherein the light sources are configured to provide an excitation to the at least one light emitting material.

13. The display apparatus according to claim 12 , wherein each light source of the array of light sources is configured to illuminate and/or excite at least one light emitting material.

14. A display apparatus, comprising:

at least one laser source; and

at least one color conversion layer,

said at least one color conversion layer comprising an array of light emitting material comprising at least one composite particle surrounded partially or totally by at least one surrounding medium,

wherein said light emitting material is configured to emit a secondary light in response to an excitation and the at least one composite particle comprises a plurality of nanoparticles encapsulated in an inorganic material,

wherein said inorganic material has a difference of refractive index compared to the at least one surrounding medium superior or equal to 0.02 at 450 nm,

wherein the plurality of nanoparticles comprises at least 1% of semiconductor nanoplatelets,

wherein a loading charge of the nanoparticles in the at least one composite particle is at least 10%, said loading charge being a mass ratio between a mass of the nanoparticles comprised in the at least one composite particle and a mass of the at least one composite particle, and

wherein said laser source is configured to provide an excitation for the at least one light emitting material.

15. A display apparatus, comprising:

at least one laser source; and

at least one color conversion layer,

said at least one color conversion layer comprising at least one light emitting material comprising at least one composite particle surrounded partially or totally by at least one surrounding medium,

wherein said at least one light emitting material is configured to emit a secondary light in response to an excitation and the at least one composite particle comprises a plurality of nanoparticles encapsulated in an inorganic material,

wherein said inorganic material has a difference of refractive index compared to the at least one surrounding medium superior or equal to 0.02 at 450 nm,

wherein the plurality of nanoparticles comprises at least 1% of semiconductor nanoplatelets,

wherein a loading charge of the nanoparticles in the at least one composite particle is at least 10%, said loading charge being a mass ratio between a mass of the nanoparticles comprised in the at least one composite particle and a mass of the at least one composite particle, and

wherein the at least one color conversion layer is deposited onto a solid support to produce images by reflection or backscattering when excited by the at least one laser source.