Organic electro luminescent display and method for fabricating the same

Abstract

An organic electro luminescent display with auxiliary layers on a cathode contact and an encapsulating junction region to easily remove polymer organic layers of the junction and a method for fabricating the same. The organic electro luminescent display has the first electrode formed on a lower insulating substrate, a pixel defining layer formed to make some portions of the first electrode opened over the entire surface of the lower insulating substrate, an organic emission layer formed on an opening of the first electrode, the second electrode formed on the organic emission layer, an upper substrate for encapsulating the first electrode, the organic emission layer and the second electrode, and auxiliary layers formed on the cathode contact and the encapsulating junction region of the lower insulating substrate.

Description

CLAIM OF PRIORITY

And ultraviolet rays or visible rays are then irradiated on the upper substrate 320 to cure the sealant 330. The optimal range for wavelength used to cure the sealant is from 200 nm to 700 nm. Another design consideration is that it is preferable to have at least 25% of the total surface area of the sealant 330 in contact with reflecting plate 267. As discussed earlier, it is preferable to form the reflecting plate 267 and the source/drain electrodes 261 and 265 at the same time to reduce the number of processing steps and to reduce manufacturing costs in the fourth embodiment. Alternatively, the reflecting plate 267 can be deposited and patterned at the same time as when the gate electrode 240 is formed. Alternatively, the reflecting plate 267 can be formed at the beginning of the process, before buffer layer 210 is formed on lower insulating substrate 200. Before forming the buffer layer 210, a material having good reflectivity, such as any one metal of Al, Mo, Ti, Ag and Mg, or an alloy containing at least one of these metals (i.e., Mo/Al/Mo, Ti/Al/Ti) may be deposited and patterned on the lower insulating substrate 200 to form the reflecting plate 267 in the encapsulating junction region of the display.

In another design consideration, the width of the reflecting plate 267 in FIG. 8 is illustrated to be larger than the contact area of the sealant 330, however, the width of the reflecting plate 267 may be formed to be smaller than the contact area contact area of the sealant 330. In such a scenario, the sealant 330 may contact lower insulating substrate 200.

The inclusion of the reflecting plate 267 in the design of the electro luminescent display attached to a light-cured sealant 330 in the edge or encapsulation junction region is advantageous for the following reason. Light used to cure the sealant 330 also exposes other portions of the electro luminescent display. This light used to cure the sealant 330 can damage other parts of the electro luminescent display. By placing a reflective plate in the encapsulation junction region of the display, less incident light energy is needed to cure the sealant because both the incident light and the reflected light can be used to cure the sealant. Therefore, the intensity of the incident light needed to cure the sealant is less if the reflecting plate is present. Therefore, because less incident light is needed to cure the sealant, less damage is sustained by the electro luminescent display during the curing process.

Turning now to FIGS. 9 and 10, FIGS. 9 and 10 illustrate top views of electro luminescent displays according to the fourth embodiment of the present invention. As is clearly illustrated in FIGS. 9 and 10, the width of the sealant 330 is greater than the width of the reflecting plate 267. Therefore, in the designs illustrated in FIGS. 9 and 10, the sealant 330 maybe in contact with lower insulating substrate 200.

In FIG. 9, the reflecting plate 267 is formed as one continuous piece in the form of a closed square. Alternatively, in FIG. 10, the reflecting plate 267 is formed of four discrete portions disconnected from each other. It is to be appreciated that the reflecting plate 267 does not serve to conduct electricity, and thus having four discrete segments in FIG. 10 works just as well as one continuous closed piece in FIG. 9.

Fifth Embodiment

FIG. 11 is a cross-sectional view showing the encapsulating junction region of the organic electro luminescent display in accordance with a fifth embodiment of the invention. The organic electro luminescent display according to the fifth embodiment has a similar structure as that of the fourth embodiment except the location of the reflecting plate 267. The reflecting plate 267 in the fifth embodiment of the present invention is in an inside surface of upper substrate 320 instead of being on the inside surface of lower insulating substrate 200. In order to form the structure of FIG. 11, after forming the TFT and the light emitting element LE on the lower insulating substrate 200 as illustrated in FIG. 7, a metal thin layer is then deposited and patterned on the inner side of the upper substrate 320 to form the reflecting plate 267 in the encapsulating junction region. As in the fourth embodiment, the upper substrate 320 is bonded to the lower insulating substrate 200 by using the sealant 330 in the encapsulating junction region.

Sixth Embodiment

FIG. 12 is a cross sectional view showing an encapsulating junction region of the organic electro luminescent display in accordance with a sixth embodiment of the invention. The organic electro luminescent display according to the sixth embodiment has a similar structure as that of the fourth and fifth embodiments except for the location of the reflecting plate 267. In the sixth embodiment, the reflecting plate 267 is located on the outer side of lower insulating plate 200. In the sixth embodiment as in the fourth and the fifth embodiments, the reflecting plate is located only in the encapsulated junction region at the edges of the electro luminescent display.

In order to make the structure of FIG. 12, after forming the TFT and the light emitting element on the lower insulating substrate 200 as illustrated in FIG. 7, the upper substrate 320 is bonded to the lower insulating substrate 200 by using the sealant 330 in the encapsulating junction region. After encapsulating the upper substrate 320 to the lower insulating substrate 200, a metal thin layer is deposited and patterned on an outer side of the lower insulating substrate 200 to form the reflecting plate 267 in the encapsulating junction region.

Seventh Embodiment

FIG. 13 is a cross sectional view showing an encapsulating junction region of the organic electro luminescent display in accordance with a seventh embodiment of the invention. The organic electro luminescent display according to the seventh embodiment has a similar structure as that of the fourth embodiment but that the reflecting plate 267 is formed on an outer side of the upper insulating plate 320 as opposed to an inner side of lower insulating substrate 200.

In order to form the structure of FIG. 13, after forming the TFT and the light emitting element on the lower insulating substrate 200 as illustrated in FIG. 7, a thin metal layer is deposited and patterned on the outer side of the upper substrate 320 to form the reflecting plate 267 in the encapsulating junction region. After forming the reflecting plate 267 in the encapsulating junction region on the outer side of the upper substrate 320, the upper substrate 320 is then bonded to the lower insulating substrate 200 by using the sealant 330 in the encapsulating junction region.

Eighth Embodiment

FIG. 14A and FIG. 14B are a cross sectional view showing an encapsulating junction region of the organic electro luminescent display in accordance with an eighth embodiment of the invention. The organic electro luminescent display according to the eighth embodiment has a similar structure as that of the fourth embodiment except that a waveguide 217 is formed on the inner side of lower insulating substrate instead of the reflecting plate 267. Preferably the wave guide is unevenness or a convex lens. FIG. 14A illustrates the wave guide 217 as unevenness. FIG. 14B illustrates wave guide 217 as a convex lens.

Referring to FIG. 14A and FIG. 14B, the wave guide 217 of the organic electro luminescent display according to the eighth embodiment is formed on the inner side of the encapsulating junction region of the lower insulating substrate 200 during the process of forming the TFT having the structure illustrated in FIG. 7 in the pixel portion. After depositing and patterning the buffer layer 210, the wave guide 217 is formed in a position corresponding to the encapsulating junction region of the lower insulating substrate 200.

Alternatively, the wave guide 217 may be formed simultaneous to the patterning the gate insulating layer 230 and after depositing the gate insulating layer 230. Alternatively, wave guide 217 can be formed simultaneous to the etching of the interlayer insulating layer 250 to form the contact holes 251 and 255. Alternatively, the wave guide 217 may be formed simultaneous to the etching of the passivation layer 270 to form the via-hole 275.

Another alternative is to form a multi-layered wave guide 217 that is formed simultaneous to the formation of the buffer layer 210, gate insulating layer 230, interlayer insulating layer 250, and passivation layer 270. Alternatively, wave guide 217 made out of material having the optical transmissivity may be formed in a separate process step separate from the process of forming the other layers in FIG. 7.

The wave guide 217 is formed by adjusting an angle in consideration of a refraction index of the incident light, and makes the incident light focused on the sealant 330 of the encapsulating junction region to be formed later by the refraction.

Ninth Embodiment

FIG. 15A and FIG. 15B are a cross-sectional view showing an encapsulating junction region of the organic electro luminescent display in accordance with a ninth embodiment of the invention. The organic electro luminescent display according to the ninth embodiment has the same structure in the pixel portion as that of the eighth embodiment except that the wave guide 217 is formed on an inner surface of the upper substrate 320 instead of on the inner surface of the lower insulating substrate. FIG. 15A illustrates wave guide 217 as unevenness and FIG. 15B illustrates wave guide 217 as a convex lens.

The method of forming the structure if FIG. 15A and FIG. 15B is as follows. After forming the TFT and the light emitting element on the lower insulating substrate 200, a material having optical transmissivity is deposited on the inner side of the upper substrate 320. The material having the optical transmissivity is then patterned to form the wave guide 217 on the inner of the upper substrate 320 in the encapsulation junction region. After forming the wave guide 217 on the inner side of the encapsulating junction region in the upper substrate 320, the lower electrode 280, the organic layer 300, and the upper electrode 310 are then formed on the upper substrate 320.

Tenth Embodiment

FIG. 16A and FIG. 16B are a cross-sectional view illustrating an encapsulating junction region of the organic electro luminescent display in accordance with a tenth embodiment of the invention. The organic electro luminescent display according to the tenth embodiment has the TFT and the light emitting element shown in FIG. 7 in the pixel portion, and has two wave guides 217, one formed on the inner surface of the upper substrate 320 and one formed on the inner surface of the lower insulating substrate 200. FIG. 16A illustrates wave guide 217 as unevenness while FIG. 16B illustrates wave guide 217 as a convex lens.

The wave guide 217 is formed on the inner side lower insulating substrate 200 is formed according to the same processes as that described in the eighth embodiment of FIG. 14A and FIG. 14B. The wave guide 217 formed on the inner side upper substrate 320 is made according to a process described in the formation of the wave guide 217 in the discussion of FIGS. 15A and 15B (the ninth embodiment). That is, the lower electrode 280, the organic layer 300, and the upper electrode 310 are then formed on an inner surface of upper substrate 320 after waveguide 217 is formed in the inner surface of upper substrate 320.

In addition, in the above-mentioned embodiments of the invention, an organic electro luminescent display having enhanced curing efficiency is disclosed by using both a reflecting plate and a wave guide formed in the upper substrate 320 or the lower insulating substrate 200 either respectively or anti respectively. Alternatively, two reflecting plates may be used, one attached to a surface of the upper substrate 320 and one attached to a surface of lower insulating substrate 200. The reflecting plates formed on both sides of the organic electro luminescent display are preferably formed to have a mirror attached to.

According to the invention, auxiliary layers are formed to remove organic layers on the encapsulating junction region, so that the invention can provide an organic electro luminescent display capable of easily removing the organic layers formed on the encapsulating junction region during the process of forming organic layers. In addition, the invention can provide a method for fabricating the organic electro luminescent display with reduced damage in the pixel portion by removing the organic layers disposed on auxiliary layers by a laser instead of removing the organic layers directly formed on the substrate.

Furthermore, according to the invention, a reflecting plate is disposed in the encapsulating junction region, so that the light emitted from the light source is reflected by the reflecting plate for curing the sealant, thereby enhancing the curing state of the sealant and putting the encapsulation of the substrates in better condition. In addition, with the reflective plate, the curing time is reduced, resulting in less damage sustained in the pixel regions of the display.

While the invention has been described with reference to a particular embodiment, it is understood that the disclosure has been made for purpose of illustrating the invention by way of examples and is not limited to limit the scope of the invention. And one skilled in the art can make amend and change the invention without departing from the scope and spirit of the invention.

Claims

1. An organic electro luminescent display, comprising:

a lower insulating substrate on which TFTs and light emitting elements are formed;

an upper substrate attached to the lower insulating substrate;

an encapsulating junction region adapted to encapsulate and attach the upper substrate to the lower insulating substrate via a sealant; and

a reflecting plate arranged only in the encapsulating junction region at any one an inner side of any one of the upper substrate and the lower insulating substrate, the reflecting plate being arranged between the inner side and the sealant.

2. The display of claim 1, the reflecting plate being formed on an the inner side of one of the upper substrate and the lower insulating substrate, the reflecting plate facing the other of the upper substrate and the lower insulating substrate.

3. The display of claim 1, the reflecting plate being formed on an outer side of one of the upper substrate and the lower insulating substrate.

4. The display of claim 1, the sealant being an optical curing sealant.

5. The display of claim 4, the sealant being an optical curable sealant cured by exposure to light in either a visible ray range or an ultraviolet ray range.

6. The display of claim 1, the reflecting plate comprising a metal thin layer deposited on any one the inner side of the upper substrate and the lower insulating substrate.

7. The display of claim 1, the reflecting plate comprising a mirror attached to the outer side of one of the upper substrate and the lower insulating substrate.

8. The display of claim 1, wherein a distance from the reflecting plate to a nearest surface of a substrate opposing the reflecting plate is designed so that curing light reflected off the reflective plate constructively interferes with curing light incident to the reflective plate.

9. The display of claim 1, the reflecting plate being a mirror.

10. An organic electro luminescent display, comprising:

a lower insulating substrate on which a pixel portion is arranged;

an upper substrate arranged over the lower insulating substrate; and

a sealing material arranged between the upper substrate and the lower insulating substrate and adapted to seal the upper substrate to the lower insulating substrate, wherein a metal layer is arranged between the lower insulating substrate and the sealing material, wherein the sealing material is formed along the peripheries of the substrates and not in the pixel portion of the display, and wherein the metal layer is formed coextensively along with the sealing material and is of the shape of a closed polygon.

11. The display of claim 10, wherein the metal layer is formed discontinuously in separate unconnected pieces around a perimeter of the display and along the sealing material.

12. The display of claim 10, the metal layer comprising a material being selected from the group consisting of Al, Mo, Ti, Ag, Mg and an alloy containing at least one of Al, Mo, Ti, Ag and Mg.

13. The display of claim 10, wherein at least 25% of the total surface area of the sealing material is in contact with said metal layer.

14. An organic electro luminescent display, comprising:

a lower insulating substrate on which a pixel portion is formed;

an upper substrate arranged on the lower insulating substrate; and

a sealing material arranged between the upper substrate and the lower insulating substrate, the sealing material being adapted to attach the upper substrate to the lower insulating substrate, the sealing material being arranged along peripheries of the substrates and outside of the pixel portion; and

a reflecting plate arranged between the lower insulating substrate and the sealing material, wherein the reflecting plate is arranged to be coextensive with the sealing material and is in the shape of a closed polygon.

15. The display of claim 14, the reflecting plate being a plurality of separate unconnected segments arranged essentially along the sealing material.

16. The display of claim 14, wherein at least 25% of an outer surface of the sealing material is in contact with the reflecting plate.

17. The display of claim 14, the reflecting plate being a mirror.

18. The display of claim 17, the metal 14, a material for the reflecting plate being selected from a the group consisting of Al, Mo, Ti, Ag, Mg and an alloy containing at least one metal of Al, Mo, Ti, Ag and Mg.

19. The display of claim 10, wherein the metal layer is formed continuously around a perimeter of the display and along the sealing material.

20. The display of claim 10, wherein the metal layer is located at corners of the shape of the closed polygon.

21. The display of claim 10, wherein the metal layer does not serve to conduct electricity.

22. An organic electro luminescent display, comprising:

a lower insulating substrate on which a pixel portion is arranged, the pixel portion comprising a plurality of light emitting elements;

an upper substrate arranged over the lower insulating substrate; and

a sealing material arranged between the upper substrate and the lower insulating substrate and adapted to seal the upper substrate to the lower insulating substrate,

wherein a metal layer is arranged between the lower insulating substrate and the sealing material,

wherein the sealing material is formed along the peripheries of the substrates and not in the pixel portion of the display, and

wherein the metal layer is formed coextensively along with the sealing material and is formed discontinuously in separate unconnected pieces around a perimeter of the display along the shape of a closed polygon.

23. The display of claim 22, wherein the metal layer does not serve to conduct electricity.

24. The display of claim 22, wherein the closed polygon has a shape of a rectangle.

25. The display of claim 22, further comprising a plurality of thin film transistors in the pixel portion, each of the thin film transistors comprising an active layer, a gate electrode, a drain electrode, and a source electrode.

26. The display of claim 25, wherein the metal layer comprises the same material as at least one of the gate electrode, the drain electrode, and the source electrode.

27. The display of claim 26, wherein the metal layer comprises the same material as the gate electrode.

28. The display of claim 25, wherein the metal layer is on a same layer as at least one of the gate electrode, the drain electrode, and the source electrode.

29. The display of claim 25, wherein each of the light emitting elements comprises:

an anode on the lower insulating substrate;

an organic layer on the anode; and

a cathode on the organic layer.

30. The display of claim 29, wherein the organic layer comprises a multi-layered structure comprising an emission layer and at least one of a hole injection layer, a hole transporting layer, an electron transporting layer, and an electron injection layer.

31. The display of claim 29, further comprising a pixel defining layer on the thin film transistors, the pixel defining layer exposing a portion of each of the anodes.

32. The display of claim 31, wherein the anodes are electrically connected to ones of the thin film transistors,

wherein the organic layers are on the exposed portions of the anodes, and

wherein the organic layers are electrically connected to the ones of the thin film transistors and are configured to emit light.

33. The display of claim 22, wherein at least 25% of a total surface area of the sealing material contacts the metal layer.

34. The display of claim 22, wherein the metal layer comprises a reflecting plate.

35. The display of claim 22, wherein the metal layer comprises at least four unconnected pieces.

36. The display of claim 22, wherein the metal layer is entirely outside of the pixel portion.

37. The display of claim 22, wherein an encapsulating junction region surrounds the pixel portion, and

wherein the metal layer is only in the encapsulating junction region.

38. The display of claim 22, wherein the sealing material comprises a light-cured material.

39. An organic electro luminescent display, comprising:

a lower insulating substrate on which a pixel portion is arranged, the pixel portion comprising a plurality of thin film transistors, each of the thin film transistors comprising

an active layer, a gate electrode, a drain electrode, and a source electrode;

an upper substrate arranged over the lower insulating substrate; and

a sealing material arranged between the upper substrate and the lower insulating substrate and adapted to seal the upper substrate to the lower insulating substrate,

wherein a metal layer is arranged between the lower insulating substrate and the sealing material,

wherein the sealing material is formed along the peripheries of the substrates and not in the pixel portion of the display, and

wherein the metal layer is formed coextensively along with the sealing material and is formed discontinuously of separate unconnected pieces around a perimeter of the display along the shape of a closed polygon.

40. The display of claim 39, wherein the metal layer does not serve to conduct electricity.

41. The display of claim 39, wherein the closed polygon has a shape of a rectangle.

42. The display of claim 39, further comprising:

an anode electrically connected to one of the thin film transistors and on the lower insulating substrate;

a pixel defining layer on the one of thin film transistors, the pixel defining layer exposing a portion of the anode;

an organic layer on the exposed portion of the anode, the organic layer being configured to emit light and being electrically connected to the one of thin film transistors; and

a cathode on the organic layer.

43. The display of claim 42, wherein the organic layer comprises a multi-layered structure comprising an emission layer and at least one of a hole injection layer, a hole transporting layer, an electron transporting layer, and an electron injection layer.

44. The display of claim 39, wherein the metal layer comprises the same material as at least one of the gate electrode, the drain electrode, and the source electrode.

45. The display of claim 44, wherein the metal layer comprises the same material as the gate electrode.

46. The display of claim 39, wherein the metal layer is on a same layer as at least one of the gate electrode, the drain electrode, and the source electrode.

47. The display of claim 39, wherein at least 25% of a total surface area of the sealing material contacts the metal layer.

48. The display of claim 39, wherein the metal layer comprises at least four unconnected pieces.

49. The display of claim 39, wherein the metal layer is entirely outside of the pixel portion.

50. The display of claim 39, wherein an encapsulating junction region surrounds the pixel portion, and

wherein the metal layer is only in the encapsulating junction region.

51. The display of claim 39, wherein the metal layer comprises a reflecting plate.

52. An organic electro luminescent display, comprising:

a lower insulating substrate on which a pixel portion is arranged;

an upper substrate arranged over the lower insulating substrate; and

a sealing material arranged between the upper substrate and the lower insulating substrate and adapted to seal the upper substrate to the lower insulating substrate,

wherein a metal layer is arranged between the lower insulating substrate and the sealing material, the metal layer not being configured to conduct electricity,

wherein the sealing material is formed along the peripheries of the substrates and not in the pixel portion of the display,

wherein the metal layer is formed coextensively along with the sealing material and is formed discontinuously in separate unconnected pieces around a perimeter of the display along the shape of a closed polygon, and

wherein the metal layer has unconnected portions at corners of the shape of the closed polygon.

53. An organic electro luminescent display, comprising:

a lower insulating substrate on which a pixel portion is arranged;

an upper substrate arranged over the lower insulating substrate; and

a sealing material arranged between the upper substrate and the lower insulating substrate and adapted to seal the upper substrate to the lower insulating substrate,

wherein a metal layer is arranged between the lower insulating substrate and the sealing material,

wherein the sealing material is formed along the peripheries of the substrates and not in the pixel portion of the display,

wherein the metal layer is formed coextensively along with the sealing material and is formed discontinuously of separate unconnected pieces around a perimeter of the display along the shape of a closed polygon, the closed polygon having a rectangular shape, and

wherein the metal layer does not serve to conduct electricity.

54. An organic electro luminescent display, comprising:

a lower insulating substrate on which a pixel portion is arranged;

a thin film transistor including an active layer, a gate electrode, a drain electrode and a source electrode disposed on the lower insulating substrate in the pixel portion;

an anode formed on the lower insulating substrate;

an organic layer formed on the anode;

a cathode formed on the organic layer;

an upper substrate arranged over the cathode; and

a sealing material arranged between the upper substrate and the lower insulating substrate and adapted to seal the upper substrate to the lower insulating substrate,

wherein a metal layer is arranged between the lower insulating substrate and the sealing material,

wherein the sealing material is formed along the peripheries of the substrates and not in the pixel portion of the display,

wherein the metal layer is formed coextensively along with the sealing material and is of the shape of a closed polygon,

wherein the metal layer is formed in unconnected pieces around a perimeter of the display and along the sealing material,

wherein the metal layer is formed of the same material and same layer as at least one of the gate electrode, the drain electrode and the source electrode,

wherein the organic layer has a multi-layered structure made up of an emission layer (EML), and at least one of a hole injection layer (HIL), a hole transporting layer (HTL), an electron transporting layer (ETL), and an electron injection layer (EIL), and

wherein the sealing material comprises light-cured material.