TW201807856A - Organic light emitting display and sealing method thereof - Google Patents

Abstract

The present invention relates to an organic light emitting display device and a sealing method therefor. The organic light emitting display device according to an embodiment of the present invention comprises: a display substrate; an encapsulation substrate disposed to face the display substrate; a display unit formed on the display substrate and including an organic light emitting element; and a sealing member for bonding the display substrate and the encapsulation substrate with the display unit disposed therebetween. Here, the sealing member is made of crystallized glass so as to minimize a difference in thermal expansion coefficient between the sealing member and a glass substrate, thereby minimizing thermal stress at a bonding surface, and also prevents the progression of cracks with respect to external impact, thereby improving the impact resistance of a display.

Description

Organic light emitting display device and sealing method thereof

The present invention relates to an organic light emitting display device and a sealing method thereof, and more particularly, to an organic light emitting display device including a sealing member formed of glass-ceramic and a sealing method thereof.

Organic light-emitting display devices are self-luminous displays that emit light by electrically exciting organic compounds. They can be driven at low voltage, have faster response speed, wide viewing angle, high contrast, and can reduce thickness and weight. Therefore, they are currently being commercialized. And people continue to research and develop organic light-emitting display devices.

Generally, an organic light emitting display device has a form in which a display substrate of a display unit is attached to a sealing substrate opposite to the display substrate through an adhesive member, and the display unit includes an organic light emitting diode to serve as a display.

In such an organic light emitting display device, for example, various internal factors cause deterioration of the light emitting layer due to oxygen from a transparent conductive oxide or the like used to form a motor for a display unit, or deterioration due to a reaction between the light emitting layer and the interface. Degradation occurred. In addition, moisture, oxygen, ultraviolet rays from the outside, and external factors that occur during the manufacturing process of the device also cause deterioration. In particular, oxygen and moisture from the outside have a fatal effect on the life of the organic light emitting element. Therefore, when manufacturing an organic light emitting display device, sealing is important.

In general, an adhesive member for bonding substrates is used as a sealing member that seals from an external environment, and such a sealing member is easily broken due to external impact or pressure. Therefore, in order to completely seal the organic light emitting elements constituting the display unit to eliminate external influences, there is still a need for an improved solution for preventing breakage of the sealing member.

The present invention aims to solve the above-mentioned problems of the prior art, and an object thereof is to provide an organic light-emitting display device that improves the strength of a sealing member for bonding organic substrates between substrates and blocking the organic light-emitting elements from the outside to prevent cracks due to external impact. And its sealing method.

An organic light-emitting display device according to an embodiment of the present invention includes: a display substrate; a sealing substrate disposed opposite to the display substrate; a display unit formed on the display substrate and including an organic light-emitting element; and a sealing member configured to pass through the display unit. The display substrate and the sealing substrate are adhered. Among them, the sealing member is formed of glass-ceramic.

According to this embodiment, the display substrate may be formed of glass, and a chemical bond may be formed at the boundary between the display substrate and the sealing member with an oxygen atom as a medium.

In addition, the organic light emitting display device according to this embodiment may further include a polarizing plate on a side of the sealing substrate that is not opposite the display substrate, and the polarizing plate is attached to the sealing substrate.

In addition, according to the present embodiment, the glass-ceramics of the sealing member may include at least one of Zn ₂ V ₂ O ₇ and α-Zn ₂ V ₂ O ₇ .

A method of sealing an organic light emitting display device according to an embodiment of the present invention includes the steps of preparing a sealing substrate and a display substrate having a display unit including an organic light emitting element; The side of one side of the sealing substrate opposite to the display substrate is coated with a sealing paste containing glass; heating at a crystallization temperature so that the glass of the applied sealing paste becomes crystalline; Arranging the display substrate such that the sealing paste is aligned with the sealing substrate; and curing the sealing paste by irradiating the sealing paste with the laser so that the display substrate and the sealing substrate are adhered.

According to the present embodiment, a laser irradiated to cure the sealing paste can be irradiated to a region on the display substrate corresponding to an end portion of the sealing paste.

In addition, the method for sealing an organic light emitting display device according to this embodiment may further include a step of attaching a polarizing plate on a side of the sealing substrate that is not opposed to the display substrate.

Moreover, according to this embodiment, the glassy crystals of the sealing paste may include at least one of Zn ₂ V ₂ O ₇ and α-Zn ₂ V ₂ O ₇ .

According to an embodiment of the present invention, by using glass-ceramic glass as a sealing member for sealing an organic light-emitting element between substrates of an organic light-emitting display device, crack progression due to external impact can be blocked to prevent damage. In addition, the crystallization of the sealing member can increase the adhesion strength between the substrate and the sealing member.

100‧‧‧Organic light-emitting display device

110‧‧‧display board

120‧‧‧Sealed substrate

130‧‧‧display unit

131‧‧‧ buffer layer

132‧‧‧Drive semiconductor layer

132c‧‧‧channel area

132d‧‧‧missing area

132s‧‧‧source area

133‧‧‧Gate insulating film

134‧‧‧Interlayer insulation film

135‧‧‧driven thin film transistor

135d‧‧‧driven drain electrode

135s‧‧‧drive source electrode

136d‧‧‧data cable

136c‧‧‧common power cord

137‧‧‧flattening film

138‧‧‧Organic light-emitting element

138c‧‧‧Common electrode

138e‧‧‧Organic light emitting layer

138p‧‧‧Element electrode

139‧‧‧Element definition film

140‧‧‧polarizing plate

150‧‧‧sealing member

151‧‧‧ Crystal

153‧‧‧Glass

FIG. 1 is a side sectional view of an organic light emitting display device according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a display unit of an organic light emitting display device according to an embodiment of the present invention.

FIG. 3 is a diagram sequentially illustrating a process of sealing an organic light emitting display device according to an embodiment of the present invention.

Figures 4 to 6 show the X-ray diffraction (X- Graph of ray Diffraction (XRD) measurement results.

FIG. 7 is an enlarged view of a boundary of a sealing member in an organic light emitting display device according to an embodiment of the present invention.

FIG. 8 is a schematic view showing a state where cracks are formed in a sealing member in a comparative example and an embodiment of the present invention.

Hereinafter, referring to the drawings, preferred embodiments of the present invention will be described in detail, so that the present invention can be easily implemented by those skilled in the art. For brevity of description, parts that are not related to the description are omitted, and the same reference numerals denote the same parts throughout the entire text.

It will be understood that when a component is referred to as being "on" another component, the component may be "directly on" the other component or intervening components may also be present therebetween. In addition, for convenience of explanation, the size and thickness of each structure shown in the drawings are arbitrarily represented, so the present invention is not limited to the parts shown in the drawings.

That is, without departing from the spirit and scope of the present invention, one embodiment of the specific shape, structure, and characteristics described in this specification can be changed and implemented in other embodiments. In addition, it should be understood that the position or arrangement of individual constituent elements of each embodiment can be changed without departing from the spirit and scope of the present invention. Therefore, the invention described below is not intended to be limited, and the scope of the invention includes the scope claimed in the claims and all scopes equivalent thereto.

FIG. 1 is a side sectional view of an organic light emitting display device according to an embodiment of the present invention. Referring to FIG. 1, the organic light emitting display device 100 according to this embodiment includes an opposite display substrate 110 and a sealing substrate 120, a display unit 130 formed on the display substrate, a polarizing plate 140 formed on the sealing substrate, and a display substrate. 110 is a sealing member 150 bonded to the sealing substrate 120.

In an embodiment of the present invention, the display substrate 110 may be formed as an insulating substrate made of glass or the like. Furthermore, in an embodiment of the present invention, the sealing substrate 120 is disposed opposite to the display substrate 110 via the display unit 130 to protect the display unit 130. In this embodiment, the sealing substrate 120 may be formed as an insulating substrate made of a transparent material such as glass, so that light generated in the display unit 130 is emitted through the sealing substrate 120.

In one embodiment of the present invention, the display unit 130 includes an organic light emitting element for emitting light when a voltage is applied.

FIG. 2 is an enlarged cross-sectional view illustrating a display unit of an organic light emitting display device according to an embodiment of the present invention. Referring to FIG. 2, in the display unit 130 according to this embodiment, a buffer may be sequentially provided on the display substrate 110. The layer 131, the driving semiconductor layer 132, the gate insulating film 133, the interlayer insulating film 134, the driving thin film transistor 135, and the planarizing film 137, and the organic light emitting element 138 may be formed on the planarizing film 137.

The organic light emitting element 138 may include a picture element electrode 138p, an organic light emitting layer 138e formed on the picture element electrode 138p, and a common electrode 138c formed on the organic light emitting layer 138e. Here, the picture element electrode 138p may be a positive (+) electrode which is a hole injection electrode, and in this case, the common electrode 138c may be a negative (-) electrode which is an electron injection electrode. Alternatively, according to the driving method of the organic light emitting display device, the picture element electrode may become a cathode and the common electrode may become an anode. Holes and electrons are injected into the organic light-emitting layer 138e from the picture element electrode 138p and the common electrode 138c, respectively. Then, when an exciton formed by combining the injected holes and electrons falls from the excited state to the ground state, Emit light. The organic light-emitting layer 138e may include a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer, so as to achieve full color of the organic light-emitting display device. For example, it is possible to form a light emitting layer of the same color in the column direction and sequentially form a red light emitting layer, a green light emitting layer, and a blue light emitting layer in the row direction. Now, or can be implemented in various other ways.

In the organic light-emitting display device 100 according to the present embodiment, the display unit 130 may be configured as a top-emission type that emits light in the direction of the sealing substrate 120. To this end, the picture element electrode 138p may use a reflective electrode and the common electrode 138c may use Transmissive or semi-transparent electrodes. However, the present invention is not limited to this, and the organic light emitting display device may be configured as a bottom emission type or a double-sided emission type.

On the other hand, the buffer layer 131 is used to prevent penetration of impurity elements and planarize the surface. One of a silicon nitride (SiNx) film, a silicon oxide (SiOx) film, and a silicon oxynitride (SiOxNy) film can be used. The driving semiconductor layer 132 formed on the buffer layer 131 may be formed as a polycrystalline silicon film, and may include a channel region 132c, a source region 132s, and a drain region 132d. The channel region 132c is not doped with impurities, and, for example, the The source region 132s and the drain region 132d are formed on both sides of the channel region 132c and are P + doped. The gate insulating film 133 may be formed of silicon nitride (SiNx), silicon oxide (SiOx), or the like, and a gate line including a driving gate (not shown) may be formed on the gate insulating film 133. An interlayer insulating film 134 that can be formed of silicon nitride (SiNx), silicon oxide (SiOx), or the like can be formed on the gate insulating film 133 in the same manner as the gate insulating film 133. The gate insulating film 133 and the interlayer insulating film 134 may be formed with a plurality of through holes exposing the source region 132s and the drain region 132d of the driving semiconductor layer 132. In addition, a data wiring including a driving source electrode 135s and a driving drain electrode 135d is formed on the interlayer insulating film 134, so that the driving source electrode 135s and the driving drain electrode 135d can pass through a plurality of through holes with the source region 132s and The drain regions 132d are connected. As described above, the driving thin film transistor 135 including the driving semiconductor layer 132, the driving gate, the driving source electrode 135s, and the driving drain electrode 135d can be formed. On the other hand, the data wiring may further include a data line 136d, a common power line 136c, and the like.

The planarizing film 137 is formed on the interlayer insulating film 134 to eliminate the step and perform planarization, so as to improve the light emitting efficiency of the organic light emitting element 138 to be formed on the planarizing film 137. level The passivation film 137 may be formed to cover the data wiring on the interlayer insulating film 134, and a contact hole 137h that exposes a part of the drain electrode 135d may be formed, and may be made of polyacrylates resin, epoxy resin ), Phenolic resin, polyamides resin, polyimides rein, unsaturated polyester resin, poly phenylenethers resin, polyphenylene ether resin It is made of at least one of polyphenylenesulfides resin and benzocyclobutene (BCB). An element definition film 139 including a plurality of openings exposing each of the element electrodes 138p may be formed on the planarization film 137. Thus, a portion where the element definition film 139 is formed may actually be a non-light emitting region and be formed. The portion having the openings of the picture element defining film 139 may actually become a light emitting region.

The above-mentioned structure of the display unit 130 including the organic light-emitting element 138 is merely exemplary, and the present invention is not limited to the above description, and its structure may be changed by those skilled in the art in a known manner. For example, any one of the planarizing film and the interlayer insulating film may be omitted, or the material constituting each layer may be changed to another known material.

Referring again to FIG. 1, in an embodiment of the present invention, the polarizing plate 140 may be formed on the sealing substrate 120 to improve the visibility of the organic light emitting display device 100. For example, the polarizing plate 140 may be configured to include a phase retardation film on the sealing substrate 120 and a polarizing film on the phase retardation film.

In an embodiment of the present invention, the sealing member 150 is used for adhering the display unit 110 between the display substrate 110 and the sealing substrate 120 and sealing the display unit 130 including an organic light emitting element therebetween, so as to prevent the display unit 130 from being exposed to moisture from the outside, Influence of oxygen, ultraviolet rays, etc. In FIG. 1, referring to a schematic enlarged cross-sectional view of the sealing member 150, the sealing member 150 according to the present embodiment may be formed by a knot Crystalline glass is formed. That is, the sealing member 150 may be formed in a shape including crystals 151 in the glassy (amorphous) 153.

In this embodiment, the sealing member is made of glass-ceramic, so that even if an impact is applied from the outside, breakage of the 151 sealing member can be suppressed and the bonding strength between the substrates can be improved. This will be described in detail later.

3 is a diagram sequentially illustrating a process of sealing an organic light emitting display device according to an embodiment of the present invention. Hereinafter, a method for sealing an organic light emitting display device will be described in detail with reference to the accompanying drawings.

First, referring to part (a) of FIG. 3, after preparing the sealing substrate 120 to which the polarizing plate 140 is attached on one side, the sealing paste is applied along the edge of the side to which the polarizing plate 140 is not attached. As described above, the sealing substrate 120 may be formed of a transparent insulating substrate such as glass, and the polarizing plate 140 may include a phase retardation film and a polarizing film sequentially attached to the sealing substrate 120. In this embodiment, although the sealing substrate 120 to which the polarizing plate 140 is attached is used, the polarizing plate 140 may be attached after the sealing substrate 120 and the display substrate 110 are adhered, or the polarizing plate 140 may not be attached.

The sealing slurry may be a slurry in which glass frit is dispersed in an organic vehicle. The organic vehicle may have a form in which an organic solvent is contained in an organic binder that imparts liquid properties to the slurry composition. As the organic binder, in addition to the acrylic polymer, one or two or more cellulose polymers can be mixed and used, and the organic solvent can be a glycol ether series, but as long as it is compatible with the organic binder, it can be used Generally known materials without limitation. The glass frit for the sealing paste may include, for example, zinc oxide (ZnO), vanadium pentoxide (V ₂ O ₅ ), tellurium dioxide (TeO ₂ ), and the like. However, the components of the above-mentioned sealing slurry are not limited to those shown in the examples, but may be changed by those skilled in the art without departing from the spirit of the present invention.

After the sealing slurry is applied and dried, as shown in part (b) of FIG. 3, the drying is performed after the drying. Firing (first heating) to crystallize the glass frit. That is, the glass frit of the slurry for sealing is dried and then made into glass-ceramic by first heating. Among them, during the drying and the first heating, the organic binder, the organic solvent and the like contained in the sealing slurry can be removed by heat volatilization.

The following Table 1 schematically shows the constituent elements contained in the glass frit, and the heating temperature required for crystallization of the glass frit may depend on the constituent elements.

FIG. 4 is a graph showing X-ray Diffraction (XRD) measurement results of glass frit of sample 2 at different first heating temperatures. Specifically, part (a) of FIG. 4 to ( Part c) shows the XRD results at the first heating temperature of 400 ° C, 430 ° C and 450 ° C, respectively.

As can be seen from FIG. 4, when the first heating was performed at a temperature of 400 ° C. (part (a) of FIG. 4), no peak point appeared in the X-ray diffraction measurement result because crystallization was not achieved, In contrast, when the first heating was performed at 430 ° C and 450 ° C (parts (b) and (c) of Fig. 4), a peak appeared in the X-ray diffraction measurement result due to the crystallization. point. That is, whether or not to crystallize is determined by the first heating temperature.

5 and 6 are graphs showing the results of X-ray diffraction measurement when the glass frit of Sample 2 is heated at 430 ° C and 450 ° C for the first time, respectively, as in FIG. 4. First, referring to FIG. 5, When the glass frit of sample 2 was heated at 430 ° C, crystals of Zn2V2O7 were mainly formed (see part (b) of FIG. 5), and therefore, the result of the X-ray diffraction measurement shown in part (a) of FIG. 5 was caused. Also, referring to FIG. 6, when the glass frit of sample 2 is heated at a temperature of 430 ° C., excluding crystallization of Zn2V2O7 (see FIG. 6) In addition to part (c)), crystals of α-Zn2V2O7 are formed (see part (b) of FIG. 6), which results in X-ray diffraction measurement results as shown in part (a) of FIG. 6.

As described above, it can be confirmed that the degree of crystallization progress and the crystal phase also change depending on the first heating temperature.

Table 2 shows values obtained by measuring the coefficient of thermal expansion (CTE) before and after crystallization. From this, it can be confirmed that the coefficient of thermal expansion after crystallization is lower than that before crystallization.

As described above, when the glass frit is crystallized by the first heating, the densification, that is, the density becomes high, and thus the thermal expansion coefficient decreases. Thus, the display substrate 110 can be made: the thermal expansion coefficient (thermal expansion coefficient of 40x10- ⁷ / ℃) glass frit bonding a thermal expansion coefficient approximating a display substrate 110, when the seal, and the stress between the display substrate 110 becomes low, Can improve the bonding strength.

Table 3 shows the results of a drop test to determine whether or not a breakage occurred in the process of increasing the drop height by testing the strength before and after crystallization of Sample 2. Specifically, the drop test before crystallization refers to two drop tests performed when the first heating is performed at a temperature of 400 ° C, and the drop test after crystallization refers to when the temperature is 430 ° C and 450 ° C, respectively. A drop test was performed on the first heating. As can be seen from Table 3, before crystallization, breakage occurred when dropped from a height of 95 cm or 87 cm. On the contrary, when it was crystallized by heating at 430 ° C for the first time, it was at a height of 118 cm. Breakage in case of falling, when carried out at 450 ℃ When it was crystallized by the first heating, it was broken only when dropped from a height of 162 cm. That is, it can be confirmed from this that the strength is increased after crystallization, and the strength varies depending on the degree of crystallization and the crystalline phase.

Next, referring to part (c) of FIG. 3, after the sealing paste is heated for the first time, the display substrate 110 on which the display unit 130 is formed is prepared and arranged so that the display substrate 110 is adhered to the sealing substrate 120. As described above, the display substrate 110 may be made of an insulating substrate such as glass, and the display unit 130 may include an organic light emitting element so that it can emit light by an electric signal.

Referring to part (d) of FIG. 3, after the display substrate 110 and the sealing substrate 120 are lined up through the crystallized glass frit for the sealing paste, the glass frit is softened and flows by irradiating laser light. Thus, the display substrate 110 and the sealing substrate 120 are adhered by the sealing member 150 to seal the two substrates so as to prevent the display unit 130 from being affected by the external environment.

In this embodiment, as shown in part (d) of FIG. 3, a region corresponding to an end portion of the applied sealing paste in the upper portion of the display substrate 110 is irradiated with laser light, thereby directly directing its energy source. It is transmitted to the glass frit so that the glass frit is melted and then cooled, so that the glass-ceramic can be maintained. Alternatively, the sealing substrate 120 may be irradiated with laser light by the same method to be cured.

In this embodiment, when a laser is irradiated, an infrared laser may be used, for example, infrared rays in a wavelength range of 800 to 820 nm. The glass frit crystallized by irradiating with laser light as described above is melted and then solidified, so that it adheres between the display substrate 110 and the sealing substrate 120. Specifically, in illuminating thunder During the shooting process, the crystals 151 in the glass powder formed by the first heating remain unchanged, but only the glassy 153 undergoes softening flow, and then remains attached to the display substrate 110 in a crystallized state.

As described above, in this embodiment, sealing is achieved by low-temperature local heating using infrared laser, and therefore, the organic light-emitting element separated from the sealed portion is subjected to a small thermal influence, so that deterioration of the element can be prevented.

On the other hand, in the process where the glass frit adheres to the display substrate 110 by irradiating a laser, a chemical bond may be formed at a boundary portion.

FIG. 7 is an enlarged view showing a state of a sealing member in an organic light emitting display device according to an embodiment of the present invention. Referring to FIG. The glass 153 of the sealing member 150 can be chemically bonded during the melting and solidification process. For example, if the glass frit includes ZnO and the display substrate 110 includes SiO ₂ , they may be chemically bonded using an oxygen atom as a medium. As described above, when the laser is irradiated, chemical bonding may occur at the boundary interface between the display substrate 110 and the sealing member 150, and thus the adhesion strength between the display substrate 110 and the sealing member 150 can be expected to be improved.

As described above, in one embodiment of the present invention, the sealing member 150 that adheres the display substrate 110 and the sealing substrate 120 of the organic light-emitting display device 100 and seals the display unit 130 including the organic light-emitting element is formed of glass-ceramic. Thereby, the adhesion strength between the substrates can be improved. Also, according to the present embodiment, the presence of crystals in the sealing member 150 can suppress breakage due to external impact.

FIG. 8 is a schematic diagram of a state where cracks are formed in a sealing member in Comparative Example (a) and Example (b) of the present invention. Referring to the drawings, as shown in part (a) of FIG. 8, in a case where the sealing member is formed in an amorphous state, when an external force above a critical point is applied, the defective portion may be easily centered. crack. In contrast, as shown in part (b) of FIG. 8, when the sealing member is formed of crystalline glass, even if an external force above the critical point is applied and the crack progresses around the defective portion as a center, the crystalline portion stops when it reaches the crystalline portion. Crack propagation.

As described above, the presence of crystals in the seal member minimizes cracks and suppresses damage even when an external force above a critical point is applied due to an external impact.

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but those with ordinary knowledge in the field to which the present invention belongs should know that other specific embodiments may occur without changing the technical idea or necessary features of the present invention. Therefore, the above-mentioned embodiments are merely illustrative and not restrictive in all respects.

100‧‧‧Organic light-emitting display device

110‧‧‧display board

120‧‧‧Sealed substrate

130‧‧‧display unit

140‧‧‧polarizing plate

150‧‧‧sealing member

151‧‧‧ Crystal

153‧‧‧Glass

Claims (8)

An organic light-emitting display device includes: a display substrate; a sealing substrate disposed opposite to the display substrate; a display unit formed on the display substrate and including an organic light-emitting element; and a sealing member using the display unit The display substrate is bonded to the sealing substrate, wherein the sealing member is formed of glass-ceramic. The organic light-emitting display device according to claim 1, wherein the display substrate is formed of glass, and a chemical bond is formed between the display substrate and the sealing member using an oxygen atom as a medium. The organic light emitting display device according to claim 1, further comprising a polarizing plate on a side of the sealing substrate that is not opposed to the display substrate, and the polarizing plate is attached to the sealing substrate. The organic light emitting display device according to claim 1, wherein the glass-ceramics of the sealing member includes at least one of Zn ₂ V ₂ O ₇ and α-Zn ₂ V ₂ O ₇ . A method for sealing an organic light-emitting display device includes the steps of preparing a sealing substrate and a display substrate having a display unit including an organic light-emitting element; Glassy sealing paste; heating at a crystallization temperature so that the glassy substance of the applied sealing paste becomes crystalline; Arranging the display substrate such that the sealing paste is aligned with the sealing substrate; and curing the sealing paste by irradiating the sealing paste with a laser so that the display substrate and the sealing substrate are cured. Phases stick together. The method for sealing an organic light emitting display device according to claim 5, wherein a laser irradiated to cure the sealing paste is irradiated onto the display substrate with the sealing paste. The area corresponding to the end. The method for sealing an organic light emitting display device according to claim 5, further comprising the step of attaching a polarizing plate on a side of the sealing substrate that is not opposite to the display substrate. The method for sealing an organic light emitting display device according to claim 5, wherein the glassy crystals of the sealing paste include at least one of Zn ₂ V ₂ O ₇ and α-Zn ₂ V ₂ O ₇ .