Hybrid material for use as coating means in optoelectronic components

Abstract

The invention relates to the use of a hybrid material comprising a) an organopolysilazane material and b) at least one surface-modified nanoscale inorganic oxide
as coating material for producing transparent layers having a thickness of less than 500 m in optoelectronic components.

Claims

1. A method of applying a transparent layer having a thickness of <500 m in an optoelectronic component, wherein I) a hybrid material comprising a) an organopolysilazane material comprising repeat units of formula (I)
[SiRRNH](I) where R and R are the same or different and are each H, methyl, ethyl, straight-chain or branched C3-C8 alkyl, C3-C8 cycloalkyl, C2-C6 alkenyl or aryl with the proviso that R and R may not both be H; and b) at least one surface-modified nanoscale inorganic oxide is applied to a surface in the optoelectronic component, II) is dried, and III) is optionally cured, and wherein at least 20% of the repeat units of formula (I) have at least one intramolecular crosslink.

2. The method as claimed in claim 1, wherein in formula (I) R and R are the same or different and are each H, methyl, ethyl, straight-chain, branched or cyclic C.sub.3-C.sub.8alkyl, phenyl, vinyl or aryl.

3. The method as claimed in claim 2, wherein in formula (I) R and R are the same or different and are each H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, phenyl or vinyl.

4. The method as claimed in claim 3, wherein in formula (I) R and R are the same or different and are each H, methyl or vinyl.

5. The method as claimed in claim 1, wherein organopolysilazanes used were crosslinked by the catalytic action of fluoride ions.

6. The method as claimed in claim 1, wherein component b) of the hybrid material consists of one or more types of inorganic oxidic nanoparticles having an average diameter in the range from 1 to 30 nm.

7. The method as claimed in claim 6, wherein the nanoparticles are selected from the group consisting of Al.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2 and TiO.sub.2.

8. The method as claimed in claim 1, wherein the nanoparticles are surface modified with alkoxysilanes of formula (V)
R.sub.nSi(OR).sub.m(V) where n is 1, 2 or 3 and m is 4n; R is methyl, ethyl, linear, branched or cyclic alkyl, of 3-8 carbon atoms, phenyl, C.sub.2-C.sub.6 alkenyl; and R is methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl.

9. The method as claimed in claim 8, wherein in formula (V) n is 1 or 3 and m is 4n; R is methyl, ethyl, linear or branched C.sub.3-C.sub.8 alkyl, phenyl or vinyl; and Ris methyl or ethyl.

10. The method as claimed in claim 9, wherein in formula (V) n is 1 or 3 and m is 4n; R is methyl, ethyl or linear or branched C.sub.3-C.sub.8 alkyl; and R is methyl or ethyl.

11. The method as claimed in claim 1, wherein the amount of inorganic nanoparticles in the hybrid material is in the range from 1 to 85 wt %.

12. The method as claimed in claim 1, wherein the optoelectronic component is an LED or a display.

13. The method as claimed in claim 12, wherein the optoelectronic component is an LED and the coating comprises luminophores and/or converters.

14. The method as claimed in claim 1, wherein the hybrid material is obtained by provision of one or more organopolysilazanes of formula (I), crosslinking of the polysilazanes of formula (I) by treatment with a fluoride catalyst, and mixing with the surface-modified nanoscale inorganic oxide.

15. The method as claimed in claim 1, wherein in step III) the organopolysilazane material is partially or completely converted into an organopolysiloxane by hydrolysis at temperatures >150 C.

16. The method as claimed in claim 1, wherein step III) is carried out at a temperature >50 C.

17. An optoelectronic component comprising one or more layers obtained from a hybrid material as described in claim 1.

18. The method as claimed in claim 1, wherein step III) is carried out at a temperature >60 C. and at a relative humidity of 70% and the nanoparticles are TiO.sub.2 or ZrO.sub.2.

19. The method as claimed in claim 1, wherein component b) of the hybrid material consists of one or more types of inorganic oxidic nanoparticles having an average diameter in the range from 3 to 20 nm.

Description

EXAMPLES

(1) Preparation of Polysilazanes Employed According to the Invention, by Fluoride Ion Catalysed Crosslinking of DURAZANE 1033 and DURAZANE 1800

Example 1

(2) In a 250 ml flask, 50 g of DURAZANE 1033 and 50 g of n-heptane were mixed under nitrogen blanketing and careful exclusion of moisture. At room temperature 0.5 g of tetramethylammonium fluoride was added. The reaction solution was heated to 60 C. over 2 h and stirred at 60 C. until gas evolution ceased (after about 2 h). After cooling down to 0 C., 200 ml of n-heptane were added and precipitated salt was filtered off. The reaction solution was initially concentrated in a rotary evaporator down to a volume of about 100 ml and then filtered again. Thereafter, the reaction solution was concentrated to dryness in the rotary evaporator, leaving 48 g of a colourless viscid oil.

Example 2

(3) In a 250 ml flask, 50 g of DURAZANE 1033 and 50 g of THF were mixed under nitrogen blanketing and careful exclusion of moisture. At 0 C. 0.5 g of tetramethylammonium fluoride was added. Spontaneous evolution of gas was observed. The reaction solution was heated to 40 C. over 4 h and stirred at 40 C. until gas evolution ceased (about 2 h). After cooling down to 0 C., 200 ml of n-heptane were added and precipitated salt was filtered off. The reaction solution was initially concentrated in a rotary evaporator down to a volume of about 100 ml and then filtered again. Thereafter, the reaction solution was concentrated to dryness in the rotary evaporator, leaving 45 g of a colourless glassy solid.

Example 3

(4) In a 250 ml flask, 50 g of DURAZANE 1800 and 50 g of acetonitrile were mixed under nitrogen blanketing and careful exclusion of moisture. At room temperature 0.5 g of caesium fluoride was added. The reaction solution was heated to 60 C. over 2 h and stirred at 60 C. until gas evolution ceased (about 2 h). After cooling down to 0 C., 200 ml of di-n-butyl ether were added and the precipitated salt was filtered off. The reaction solution was initially concentrated in a rotary evaporator down to a volume of about 100 ml and then filtered again. Thereafter, the reaction solution was concentrated to dryness in the rotary evaporator, leaving 47 g of a colourless to slightly pale yellow glassy solid.

Example 4

(5) In a 250 ml flask, 50 g of DURAZANE 1800 and 50 g of THF were mixed under nitrogen blanketing and careful exclusion of moisture. At 0 C. 0.5 g of tetraethylammonium fluoride was added. Spontaneous evolution of gas was observed. The reaction solution was heated to 20 C. over 2 h and stirred at 20 C. until gas evolution ceased (about 4 h). After cooling down to 0 C., 200 ml of n-heptane were added and precipitated salt was filtered off. The reaction solution was initially concentrated in a rotary evaporator down to a volume of about 100 ml and then filtered again. Thereafter, the reaction solution was concentrated to dryness in the rotary evaporator, leaving 46 g of a colourless glassy solid.

(6) TABLE-US-00001 TABLE 1 Summary of examples Example Raw material Solvent Catalyst Temperature Molar weight* Consistency [mPas] 1.sup.st DURAZANE n-heptane NMe.sub.4F 60 C. 5200 liquid/oil ca. 5000 1033 2.sup.nd DURAZANE THF NMe.sub.4F 40 C. 10300 solid 1033 3.sup.rd DURAZANE acetonitrile CsF 60 C. 12700 solid 1800 4.sup.th DURAZANE THF NEt.sub.4F 20 C. 13900 solid 1800 DURAZANE 2500 liquid 19 1033 DURAZANE 2800 liquid 80 1800 *the molar weight was determined by GPC (gel permeation chromatography) against polystyrene standards

(7) Comparison of Example 1 with Example 2 shows that the extent of the crosslinking reaction can be intentionally controlled via the choice of reagents. A deliberately low degree of crosslinking provides a product of medium molar weight and liquid, viscid to oily consistency (Ex. 1.sup.st), while a high degree of crosslinking provides a product that is obtained in the form of a solid (Ex. 2.sup.nd).

(8) DURAZANE 1033 and the crosslinked product of Ex. 2.sup.nd were subjected to a thermogravimetric analysis (TGA: loss of weight on heating). DURAZANE 1800 and the crosslinked product of Ex. 3.sup.rd were likewise subjected to the recording of a TGA.

(9) Comparing the low molecular weight starting materials with the corresponding crosslinked products shows a distinct decrease in the vaporizable fractions of the crosslinked products.

(10) Comparing the GPC spectra of DURAZANE 1033, DURAZANE 1800 and the corresponding crosslinked-solid products of Example 2 and Example 3 is clear in showing the higher molar weight coupled with the reduced fraction of oligomers.

(11) A solution of DURAZANE 1033 in dibutyl ether and a dibutyl ether solution of the crosslinked product of Example 2 were used to spin coat a 3 inch wafer with a layer 1.0 m in thickness. The wafer was then baked on a hotplate at 200 C. for 1 hour. After cooling down to room temperature, a Dektak profilometer (mechanical layer-thickness measuring instrument) was used to measure the variation in layer thickness across the wafer. The same comparison was carried out with DURAZANE 1800 and the crosslinked product of Example 3.

(12) A comparison of the low molecular weight starting materials with the corresponding crosslinked products shows a distinct reduced variation in layer thickness for the wafers coated with crosslinked products. This result suggests that the products crosslinked according to the invention have significantly improved coating properties.