Organic el display

Abstract

An object of the present invention is to provide an organic EL display that has a reduced optical loss and high efficiency, and can be manufactured by an inexpensive method. The organic EL display of the present invention is formed by bonding an organic EL element substrate including a substrate, reflective electrode, organic EL layer, separation wall, barrier layer, transparent electrode, and color conversion layer; and a sealing substrate together, wherein: the reflective electrode includes a plurality of partial electrodes; the organic EL layer is formed on the reflective electrode and includes a plurality of parts separated by the separation wall; the transparent electrode is formed on the organic EL layer; the barrier layer covers the separation wall and the transparent electrode, and has a recessed part in a location corresponding to the reflective electrode; and the color conversion layer is formed in the recessed part.

Description

REFERENCE TO RELATED APPLICATIONS[0001]This application is a national stage application under 35 USC 371 of International Application No. PCT / JP2009 / 006171, filed Nov. 17, 2009, the entire contents of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention mainly relates to an organic EL display.BACKGROUND OF THE INVENTION[0003]A panel unit of an organic EL display having a top emission structure typically has a configuration in which an organic EL element substrate (a TFT substrate) and a color filter substrate are bonded together.[0004]An organic EL element substrate having a conventional structure includes, for example, a glass substrate, a TFT structure, planarizing resin, an inorganic passivation film that may be optionally provided, an underlying layer for enhancing adhesiveness, reflective electrodes, an insulating film that has openings in locations serving as light emitting parts, an organic EL layer, a transparent electrode (including s...

AI Technical Summary

Benefits of technology

[0017]Therefore, an object of the present invention is to provide an organic EL display that has a reduced optical loss and high efficiency and is inexpensive, in the field of a top emission type organic EL display based on a color conversion system. Also, another object of the present invention is to provide a large screen organic EL display that has increased bonding strength in a display area, and exhibits high resistance to heat shock and impact. Further, still another object of the present invention is to provide an organic EL display that enables selectivity of filler included in a bonding gap to be expand and can be manufactured by a simple method. An organic EL display of the present invention is formed by bonding together: an organic EL element substrate comprising a substrate, a reflective electrode, an organic EL layer, a separation wall, a barrier layer, a transparent electrode, and a color conversion layer; and a sealing substrate, wherein: the reflective electrode is constituted of a plurality of partial electrodes; the organic EL layer is formed on the reflective electrode and is constituted of a plurality of parts that are separated by the separation wall; the transparent electrode is formed on the organic EL layer; the barrier layer covers the separation wall and the transparent electrode, and has recessed parts in a location corresponding to the reflective electrode; and the color conversion layer is formed in the recessed parts. Here, a refractive index of the color conversion layer is desirably equal to or more than a refractive index of the barrier layer. Also, the sealing substrate may further comprise a color filter.

[0020]The organic EL display of the present invention can achieve significant improvement of color conversion efficiency. This working effect arises from the facts that (a) in the present invention, formation of the color conversion layer on the barrier layer of the organic EL element substrate to discreate a distance between the barrier layer and the color conversion layer corresponds to making all of light exited from the barrier layer reach a surface of the color conversion layer of an intended sub pixel in the conventional structure, and that (b) the absence of a low refractive index layer between the barrier layer and the color conversion layer, i.e., in a path from the light emitting layer to the color conversion layer reduces reflection losses at interfaces between the respective layers.

[0022]Further, in the organic EL display of the present invention, no bonding gap is present in a light path from the organic EL layer to the color conversion layer, and therefore a conventional material such as a typical adhesive can be used as a material to be filled at the time of bonding. To increase the number of options for the filling material enables a manufacturing method to be simplified and / or manufacturing cost to be reduced due to a reduction in material cost. Also, in the organic EL display of the present invention, without newly forming the separation wall, it is possible to form a structure (such as the auxiliary wiring or transparent electrode separated wiring), in which a separation wall on the organic EL element substrate side is necessary to manufacture. Even if such a structure is formed, the color conversion layer can be formed by an application method. This is also advantageous to reduction of the manufacturing cost of the organic EL display.

[0023]In addition, in the organic EL display of the present invention, the bonded parts, in which the organic EL element substrate is adhered with the sealing substrate without interposition of the organic EL layer, are present throughout a whole of the display area, and therefore mechanical strength of the bonding is increased to improve mechanical reliability. Besides, acquisition of the mechanical strength in the display area leads to a possibility of production of a display having an extremely narrow circumferential frame in future, by eliminating necessity of an outer circumferential seal part.

Problems solved by technology

If the bonding gap is too wide, a crosstalk problem that light penetrates into an adjacent pixel is concerned.

In particular, in the case of enclosing the filler in the bonding gap, if the bonding gap is too narrow, the included filler may distribute unevenly.

In addition, in the case where the transversely deviated light enters an adjacent different color sub pixel, the color conversion layer of the adjacent sub pixel may emit converted light and the emitted light may produce undesired hue.

Further, the thin-film organic EL layer has extremely low mechanical strength.

Therefore in the organic EL display employing the bonding structure as described above, mechanical bonding strength in the display area can not be expected at all.

Also, a structure involving a hollow bonding gap has been proposed by many institutions from the start time of the organic EL display; however, it goes without saying that such a structure is not advantageous to manufacturing of the large screen display.

However, in the case where the structure in which the filler is enclosed in the bonding gap is adopted and the filler has a lower refractive index than that of the barrier layer, total reflection occurs at an interface between the barrier layer and the filler, preventing sufficient amount of light from being transmitted, and therefore resulting in an optical loss.

In addition, such filler is a special and expensive material, and therefore becomes a factor for increasing manufacturing cost.

Further, Japanese Patent Laid-Open No. 2006-32010 does not disclose sealing based on substrate bonding; however, the sealing is practically required.

Therefore, as described above, there is a concern on insufficient mechanical strength due to the thin film organic EL layer.

Even if taking countermeasures against the insulating film used as the bank (more stringent heat treatment condition at the time of forming the insulating film, or the formation of the insulating film with an inorganic material), continuity of the organic EL layer over the whole display area, per se, may cause broad area transmission of the outgas that penetrates through the protective layer.

In particular, in the case of applying a color converting material on the protective layer to form the color conversion layer by a wet process such as an inkjet method, the organic EL layer is significantly damaged by a component penetrating through the protective layer.

This is because it is necessary to dilute the color converting material down to 1 to a few % with an organic solvent that significantly damages the organic EL layer in the formation of the color conversion layer by the wet process.

This situation is tantamount to applying the solvent on the organic EL layer and protective layer, therefore dramatically increasing a possibility that the component damaging the organic EL layer penetrates from defects such as pinholes, which are sparsely present in the protective layer, to give rise to dark areas in a wide region of the display area.

However, in such an organic EL display in which the organic EL element substrate is bonded to the color filter substrate having the color conversion layer, it is easily inferred that a height of the separation wall on the color filter side and a height of the separation wall on the organic EL element substrate side are simply summed, which further increases an optical loss.

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