Hybrid material for optoelectronic applications

1. A hybrid material for light emitting diodes, comprising

a) an organopolysilazane material, comprising repeating units of formulae (I) and (II)

wherein the symbols and indices have the following meanings:

R 1 is C 2 -C 6 -alkenyl or C 4 -C 6 -alkadienyl;

R 2 is H or an organic group;

R 3 is H or an organic group;

R 4 is H or an organic group;

R 5 is H or an organic group;

x is 0.001 to 0.2; and

y is 2x to (1−x),

with the proviso that x+y≤1 and that y can be 0 if R 2 is H, and

(b) inorganic nanoparticles having a mean diameter in the range of from 1 to 30 nm, which are surface modified with a capping agent comprising a C 1 -C 18 -alkyl and/or C 1 -C 18 -alkenyl group.

2. The material according to claim 1 , wherein

R 1 is (C 2 -C 6 )-alkenyl or (C 4 -C 6 )-alkadienyl;

R 2 is (C 1 -C 8 )-alkyl, (C 2 -C 6 )-alkenyl, (C 3 -C 6 )-cycloalkyl, (C 6 -C 10 )-aryl or H;

R 3 is H or (C 1 -C 8 )-alkyl, (C 2 -C 6 )-alkenyl, (C 3 -C 6 )-cycloalkyl or (C 6 -C 10 )-aryl;

R 4 is H or (C 1 -C 8 )-alkyl, (C 2 -C 6 )-alkenyl, (C 3 -C 6 )-cycloalkyl or (C 6 -C 10 )-aryl;

R 5 is H or (C 1 -C 8 )-alkyl, (C 2 -C 6 )-alkenyl, (C 3 -C 6 )-cycloalkyl or (C 8 -C 10 )-aryl;

x is 0.02 to 0.1 and

y is preferably 2*x to 0.98.

3. The material according to claim 1 wherein

R 1 is vinyl or allyl;

R 2 is (C 1 -C 4 )-alkyl, phenyl or H;

R 3 is H;

R 4 is (C 1 -C 4 )-alkyl, phenyl or H;

R 5 is H;

x is 0.03 to 0.075 and

y is 2*x to 0.97.

4. The material according to claim 1 , wherein

R 1 is vinyl;

R 2 is methyl, ethyl, propyl or phenyl;

R 3 is H and

R 4 is methyl, ethyl, propyl or phenyl;

R 5 is H;

x is 0.03 to 0.06 and

y is 2*x to 0.97.

5. The material according to claim 1 , wherein the organopolysilazane comprises one or more organopolysilazane comprising a repeating unit of formula (I) and/or formula (II) and one or more repeating units of formula (III) and/or (IV),

wherein

R 6 , R 7 , and R 9 are independently an organic group;

R 10 is H or an organic group, and

R 8 and R 11 are independently H or an organic group.

6. The material according to claim 5 , wherein the symbols in formulae (III) and (IV) have the following meanings:

R 6 , R 7 and R 9 are independently (C 1 -C 8 )-alkyl, (C 3 -C 6 )-cycloalkyl or (C 6 -C 10 )-aryl;

R 10 is independently (C 1 -C 8 )-alkyl, (C 3 -C 6 )-cycloalkyl or (C 6 -C 10 )-aryl, (C 2 -C 6 )-alkenyl, (C 4 -C 6 )-alkadienyl or H and

R 8 and R 11 are H, (C 1 -C 8 )-alkyl, (C 3 -C 6 )-cycloalkyl or (C 8 -C 10 )-aryl.

7. The material according to claim 1 , wherein the molecular weight M w of the organopolysilazanes is in the range of 2000-150.000.

8. The material of claim 1 , wherein the organopolysilazane material has a viscosity of 100-100.000 mPas at 25° C.

9. The material according to claim 1 , wherein the amount of low molecular material with M w <500 g/mol in the organopolysilazane material is below 15 wt.-%.

10. The material according to claim 1 , wherein the inorganic nanoparticles have an average mean diameter in the range of from 3 to 20 nm.

11. The material according to claim 1 , wherein the inorganic nanoparticles are selected from the group consisting of semiconductor nanoparticles, metal nanoparticles, metal oxide nanoparticles and a combination comprising at least one of the foregoing.

12. The material according to claim 11 , wherein the inorganic nanoparticles are selected from the group consisting of ZrO 2 , BaTiO 3 and TiO 2 .

13. The material according to claim 1 , wherein the inorganic nanoparticles are surface modified with a alkoxysilane or chlorosilane capping agent.

14. The material according to claim 13 , wherein the capping agent is selected from methyltrimethoxysilane, trimethylmethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-octyltrimethoxysilane, n-octyltriethoysilane, phenyltrimethoxysilane, 2-[methoxy(polyethyleneoxy)propyl]-trimethoxy-silane, methoxy(triethyleneoxy)propyltrimethoxysilane, 3-aminopropyltri-methoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropyl-trimethoxysilane and glycidoxypropyltrimethoxysilane.

15. The material according to claim 13 , wherein the capping agent is selected from alkoxysilanes of formula (V)

R″ n Si(OR′″) m    (V)

wherein

n is 1, 2 or 3 and m is 4-n;

R″ is methyl, ethyl, linear, branched or cyclic alkyl with 3-8 carbon atoms, phenyl, (C 2 -C 6 )-alkenyl; and

R′″ is methyl, ethyl, n- or iso-propyl, n- or isobutyl.

16. The material according to claim 1 , wherein the amount of inorganic nanoparticles is in the range of from 1 to 85% by weight, based on the whole material.

17. The material according to claim 1 , wherein the refractive index of the material is in the range of from 1.35 to 2.50.

18. A process for producing an LED, comprising the steps of

I) encapsulating the light emitting material of the LED with a hybrid material according to claim 1 , by dispensing the material and

II) curing the organopolysilazane of the invention optionally adding curing catalyst for 1 min to 6 h at a temperature of from 80° C. to 220° C. in an inert atmosphere or air.

19. The process of claim 18 , comprising the steps

Ia) providing a material according to claim 1 by mixing the organopolysilazane in solution with a nanoparticle dispersion, removing the solvent and

Ib) applying the material to the LED as an encapsulation material.

20. An encapsulation material for LEDs, obtainable by

a) providing a material according to claim 1 ,

b) optionally subjecting the material to crosslinking by treatment with a base, and

c) curing the material optionally adding curing catalyst by treating the material to a temperature in the range of from 80 to 220° C. for a period of from 1 min to 6 h in an inert atmosphere or air.

21. An LED, comprising the material according to claim 1 as an encapsulation material.