Substrate for device having an organic light-emitting diode

Abstract

A diffusing substrate for a device having an organic light-emitting diode including a sheet of glass coated on one of the surfaces thereof with a layer including a vitreous material, such that the vitreous material has a chemical composition including the following components, which vary within the weight limits defined below: TABLE-US-00001 Bi.sub.2O.sub.3 60-85% B.sub.2O.sub.3 5-12% SiO.sub.2 6-20% MgO + ZnO 0-9.5%.sup. Al.sub.2O.sub.3 0-7% Li.sub.2O + Na.sub.2O + K.sub.2O 0-5% CaO 0-5% BaO 0-20%.

Claims

1. A scattering substrate for a device having an organic light-emitting diode comprising a sheet of glass coated on one of the faces thereof with a layer comprising a vitreous material, such that said vitreous material has a chemical composition comprising the following constituents, which vary within the weight limits defined hereinafter: TABLE-US-00010 Bi.sub.2O.sub.3 60-85% B.sub.2O.sub.3 5-12% SiO.sub.2 6-10% MgO + ZnO 0-9.5% Al.sub.2O.sub.3 0-7 Li.sub.2O + Na.sub.2O + K.sub.2O 0.02-5% CaO 0-5% BaO 0-20%, wherein a glass transition temperature Tg of glass constituting the vitreous material is in a range from 440 to 480? C.

2. The scattering substrate as claimed in claim 1, wherein the weight content of Bi.sub.2O.sub.3 is included in a range of from 65% to 80%.

3. The scattering substrate as claimed in claim 2, wherein the weight content of Bi.sub.2O.sub.3 is included in a range of from 68% to 75%.

4. The scattering substrate as claimed in claim 1, wherein the weight content of ZnO is at most 8%.

5. The scattering substrate as claimed in claim 4, wherein the weight content of ZnO is less than 5%.

6. The scattering substrate as claimed in claim 1, wherein the weight content of SiO.sub.2 is included in a range of from 7% to 9%.

7. The scattering substrate as claimed in claim 1, wherein the sum of the weight contents of MgO and ZnO is included in a range of from 2% to 9%.

8. The scattering substrate as claimed in claim 1, wherein the sum of the weight contents of CaO and MgO is included in a range of from 0.5% to 4%.

9. The scattering substrate as claimed in claim 1, wherein the chemical composition of the vitreous material comprises the oxides TiO.sub.2 and/or SnO.sub.2.

10. The scattering substrate as claimed in claim 9, wherein the TiO.sub.2 content is at least 0.5% or 1% and at most 5%.

11. The scattering substrate as claimed in claim 10, wherein the TiO.sub.2 content is at most 2%.

12. The scattering substrate as claimed in claim 9, wherein the SnO.sub.2 content is at least 0.2% or 0.5% and at most 5%.

13. The scattering substrate as claimed in claim 12, wherein the SnO.sub.2 content is at most 3%.

14. The scattering substrate as claimed in claim 1, wherein the layer comprising a vitreous material also comprises scattering elements chosen from particles and cavities.

15. The substrate as claimed in claim 14, wherein the particles are chosen from aluminum particles, zirconia particles, silica particles, titanium dioxide particles, calcium carbonate particles and barium sulfate particles.

16. The substrate as claimed in claim 1, wherein the layer comprising a vitreous material consists of said vitreous material, and wherein the sheet of glass scatters light or a scattering layer is placed under the layer comprising a vitreous material.

17. The scattering substrate as claimed in claim 1, wherein an electrically conductive layer is placed on the layer comprising a vitreous material.

18. A device having an organic light-emitting diode, comprising a scattering substrate as claimed in claim 17.

19. The scattering substrate as claimed in claim 1, wherein the sum Li.sub.2O+Na.sub.2O+K.sub.2O is 0.05-5%.

20. The scattering substrate as claimed in claim 1, wherein the weight content of Al.sub.2O.sub.3 is 1-4%.

21. The scattering substrate as claimed in claim 19, wherein the only alkali metal oxide present in the chemical composition is Na.sub.2O.

22. A glass frit of which the chemical composition comprises the following constituents, which vary within the weight limits defined hereinafter: TABLE-US-00011 Bi.sub.2O.sub.3 65-85% B.sub.2O.sub.3 5-12% SiO.sub.2 6-10% MgO + ZnO 0-9.5%.sup. Al.sub.2O.sub.3 0-5% Li.sub.2O + Na.sub.2O + K.sub.2O 0.02-5% CaO 0-5% CaO + MgO ?0.5 BaO 0-20%, wherein a glass transition temperature Tg of glass constituting the vitreous material is in a range from 440 to 480? C.

23. The glass frit as claimed in claim 22, wherein the sum Li.sub.2O+Na.sub.2O+K.sub.2O is 0.05-5%.

24. The glass frit as claimed in claim 23, wherein the only alkali metal oxide present in the chemical composition is Na.sub.2O.

25. The glass frit as claimed in claim 22, wherein the weight content of SiO.sub.2 is included in a range of from 7% to 9%.

Description

FIRST SERIES OF EXAMPLES

(1) Various glass frits were obtained by melting starting materials. To do this, the starting materials sufficient to obtain 300 g of glass were brought to a temperature of 1000? C. for 1 h 30 in crucibles, heated by Joule effect, of 400 cm.sup.3.

(2) Tables 3, 4 and 5 summarize the results obtained. The following are indicated in these tables: the chemical composition of the frit (as weight percentage of oxide), the glass transition temperature, denoted Tg and expressed in ? C., the crystallization temperature, denoted T.sub.x and expressed in ? C., the linear thermal expansion coefficient, denoted ? and expressed in 10.sup.?7/K, the refractive index for a wavelength of 550 nm, denoted n, measured by ellipsometry, the light absorption for a thickness of 3 mm, denoted AL, measured by spectrophotometry, the leaching of bismuth in acidic medium, denoted L and expressed in mg/l.

(3) Like the Tg, the T.sub.x is measured by differential scanning calorimetry.

(4) The bismuth leaching was measured by immersing glass substrates coated with a layer of the vitreous material studied in an acidic solution. To do this, layers 10 ?m thick were deposited by screen printing on soda-lime-silica glass substrates, using frits having a d90 of 3.4 ?m and a d50 of 1.7 ?m. The acidic solution is an acetic acid-based solution sold under the reference Neutrax by the company Franklab, diluted to 1.3% by volume in deionized water in order to achieve a pH of 3. The samples were immersed in this solution at a temperature of 50? C. for one hour, and a small amount of solution was removed every 10 minutes and then analyzed in order to deduce therefrom the amount of Bi.sub.2O.sub.3 having passed into solution. The number indicated in the tables corresponds to the concentration of Bi.sub.2O.sub.3 in the attack solution after 10 minutes.

(5) Examples 1 to 10 (tables 3 and 4) are examples according to the invention, while examples C1 to C6 are comparative examples.

(6) TABLE-US-00006 TABLE 3 1 2 3 4 5 Bi.sub.2O.sub.3 73.1 74.5 73.7 72.3 72.4 ZnO 5.54 5.31 5.39 9.34 7.9 SiO.sub.2 7.9 7.7 7.9 7.6 9.4 B.sub.2O.sub.3 7.71 7.8 7.74 6.31 6.86 Al.sub.2O.sub.3 2.5 2.5 2.4 2.4 2.5 Na.sub.2O 0.1 0.11 0.11 0.1 0.08 CaO 3.1 0 1.7 1.9 0.04 MgO 0 2 1 0 0 MgO + ZnO 5.54 7.31 6.39 9.34 7.9 MgO + CaO 3.1 2 2.7 1.9 0.04 Tg(? C.) 460 468 464 456 455 T.sub.x (? C.) 693 678 668 ?(10.sup.?7/K) 88.7 82.2 84.2 84.9 77.5 n 1.91 1.93 1.93 1.92 1.90 AL (%) 9.4 7.3 10.3 11.1 7.4 L (mg/l) 1.6 1.5 1.56 1.62 1.72

(7) TABLE-US-00007 TABLE 4 6 7 8 9 10 Bi.sub.2O.sub.3 72 74.8 75.9 77.2 77 ZnO 4.87 2.68 0.08 4.51 2.51 SiO.sub.2 11.4 9.2 8.4 7.8 7.6 B.sub.2O.sub.3 8.37 8.36 10.4 6.18 9.46 Al.sub.2O.sub.3 2.7 2.7 2.6 2.3 2.4 Na.sub.2O 0.09 0.08 0.09 0.09 0.09 CaO 0 0 0 0 0 MgO 0 2.1 2.1 1.9 1 MgO + ZnO 4.87 4.78 2.18 6.41 3.51 MgO + CaO 0 2.1 2.1 1.9 1 Tg(? C.) 457 475 478 475 458 T.sub.x (? C.) 682 678 683 677 668 ?(10.sup.?7/K) 76.9 77.1 86.4 77.2 82.9 AL (%) 8.3 10.5 8.5 7.3 8.1 n 1.89 1.91 1.89 1.96 1.92 L (mg/l) 1.48 1.52 1.42 1.76 1.7

(8) TABLE-US-00008 TABLE 5 C1 C2 C3 C4 C5 C6 Bi.sub.2O.sub.3 71.9 72.7 72.5 72.2 72.3 70 ZnO 10.7 10.7 10.4 9.87 9.23 10 SiO.sub.2 7.8 7.6 7.6 7.6 7.8 7 B.sub.2O.sub.3 5.62 5.7 5.8 6.58 6.29 9 Al.sub.2O.sub.3 2.5 2.4 2.4 2.5 2.6 3 Na.sub.2O 0.1 0.09 0.11 0.1 0.1 1 CaO 1.4 0 0.7 0 1 0 MgO 0 0.9 0.4 1.2 0.6 0 MgO + ZnO 10.7 11.6 10.8 11.07 9.83 10 MgO + CaO 1.4 0.9 1.1 1.2 1.6 0 AL (%) 24.5 28.6 22.4 22.9 15.8 L (mg/l) 1.9

(9) Comparative examples C1 to C5 devitrify too easily to be able to be formed into vitreous material, hence their very high light absorption. The examples according to the invention all exhibit a resistance to acids that is significantly better than that of comparative example C6.

Second Series of Examples

(10) Other glasses according to the invention were obtained by melting, as in the case of the first series of examples. The chemical composition thereof is indicated in table 6 hereinafter.

(11) The resistance to acids of these glasses was evaluated on the bulk glass samples. The samples, all having the same surface area, were immersed in the same attack solution as that described previously, for a period of 18 hours. The loss of mass of the sample, expressed in mg/cm.sup.2 is called Ma in table 6. The loss of mass in the case of the comparative glass C6 is 15 mg/cm.sup.2.

(12) The resistance to bases was also evaluated by measuring the loss of mass (denoted Mb) obtained having immersed the samples in a solution at pH 11 (solution, diluted to 1%, of the concentrate sold by the company Borer under the brand Deconex? PV 110) for 18 h at 50? C.

(13) TABLE-US-00009 TABLE 6 11 12 13 14 15 Bi.sub.2O.sub.3 77.8 74.0 75.1 70.6 78.6 ZnO 0 0 0 0 0 SiO.sub.2 10.5 11.0 10.2 10.8 10.1 B.sub.2O.sub.3 9.5 7.4 6.8 10.4 7.7 Al.sub.2O.sub.3 2.0 5.4 5.0 3.4 2.7 Na.sub.2O 0 0.1 0.1 0.1 0.1 CaO 0 0 0 4.7 0 TiO.sub.2 0 2.1 0 0 0 SnO.sub.2 0 0 0 0 0.8 Sb.sub.2O.sub.3 0 0 2.9 0 0 Ma (mg/cm.sup.2) 9 3.8 8 14 11.6 Mb (mg/cm.sup.2) 4 1 4 8 4