TWI549332B - Organic light-emitting devices and fabrication method thereof - Google Patents

Description

Organic light-emitting element and its preparation method

The present invention relates to an organic light-emitting element, and more particularly to an organic light-emitting element which improves the light-emitting lifetime.

In recent years, organic light-emitting devices (OLEDs) have attracted attention due to high brightness, fast refresh rate, and wide color gamut, and this feature makes OLEDs more suitable for portable electronic components.

In general, the organic light-emitting element includes an anode, a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode which are sequentially deposited by a vacuum deposition method or a coating method. When the organic light emitting element conducts a voltage, the anode is injected into the hole, and the cathode injects electrons into the (plural) organic layer, and the injected hole enters the light emitting layer through the hole transport layer, and the electron migrates into the light emitting layer through the electron transport layer. In the luminescent layer, electrons and holes are combined to produce excitons. The excitons emit light by being relaxed by the illuminating mechanism.

However, the OLEDs studied today are multi-layered structures. Since electrons and holes are conducted in the components, they are susceptible to the difference in energy barrier between the layers and the interface, resulting in a large number of carriers accumulating at the interface between the organic semiconductor layers. In turn, loss and recombination rate are reduced, resulting in a decrease in component operating life.

Therefore, there is an urgent need to develop an OLED that can improve the luminescence lifetime.

The present invention provides an organic light emitting device comprising: a first electrode; a flat layer formed on the first electrode; a light emitting layer formed on the flat layer, the flat layer being sandwiched between the first electrode and the light emitting layer And a second electrode formed on the light-emitting layer, the light-emitting layer being sandwiched between the flat layer and the second electrode; wherein the light-emitting layer comprises a double-host material and a light-emitting material.

The organic light-emitting element of the present invention includes only one light-emitting layer in addition to the most commonly used flat layer (PEDOT:PSS) on the current OLED process between the first electrode and the second electrode, and no additional hole transport layer is required. Or an electronic transport layer. Specifically, the organic light-emitting element of the present invention introduces an electron and a hole transport material into the light-emitting layer, and replaces the general three layers (hole transport layer/light-emitting layer/electron transport layer) or three or more layers with a single layer (light-emitting layer). OLED structure. Therefore, the OLED of the present invention can avoid the problem of energy loss due to the generation of carrier accumulation between layers, and can improve the luminescent lifetime of the OLED.

The present invention provides a method of fabricating an organic light-emitting device, comprising: forming a planar layer on a first electrode; forming a light-emitting layer on the planar layer, the flat layer being sandwiched between the first electrode and the light-emitting layer, Wherein, the luminescent layer comprises a double body material and a luminescent material; and a second electrode is formed on the luminescent layer, the luminescent layer being sandwiched between the flat layer and the second electrode.

In addition to the characteristics of simple process and low production cost, the OLED produced by the invention also has a long luminescence lifetime.

10‧‧‧Organic light-emitting elements

110‧‧‧First electrode

120‧‧‧flat layer

130‧‧‧Lighting layer

140‧‧‧second electrode

1 is a schematic cross-sectional view showing the structure of an organic light-emitting element of the present invention; and FIG. 2 is a view showing an illuminating lifetime of an organic light-emitting element including different numbers of layers.

The following examples are intended to illustrate the invention, and the scope of the patent application of the present invention It will not be restricted as a result. The present invention may be embodied or applied in various other embodiments, and various modifications and changes can be made without departing from the spirit and scope of the invention.

It is to be understood that the structure, the proportions, the size, and the like of the present invention are intended to be used in conjunction with the disclosure of the specification, and are not intended to limit the invention. The conditions are limited, so it is not technically meaningful. Any modification of the structure, change of the proportional relationship or adjustment of the size should remain in this book without affecting the effects and the objectives that can be achieved by the present invention. The technical content disclosed in the invention can be covered. In the meantime, the terms "upper", "first" and "second" as used in the specification are merely for convenience of description, and are not intended to limit the scope of the invention. Changes or adjustments are considered to be within the scope of the invention, without departing from the scope of the invention.

The present invention provides a method of fabricating an organic light-emitting device, comprising: forming a flat layer on a first electrode; contacting the flat layer to form a light-emitting layer, wherein the flat layer is sandwiched between the first electrode and the light-emitting layer, Wherein, the luminescent layer comprises a double body material and a luminescent material; and contacting the luminescent layer to form a second electrode, the luminescent layer being sandwiched between the flat layer and the second electrode between.

In the foregoing process, the electrode may comprise a metal or metal substitute. The metal refers to a material containing a metal element or a material containing a metal alloy, wherein the metal alloy is a material containing two or more metals. Metal substitute refers to a material having a metalloid nature, such as a doped semiconductor or a transparent conductive oxide such as indium tin oxide (ITO). Typically, indium tin oxide is used as the anode. The cathode can usually be made of a layer of metal or two layers of metal such as calcium/aluminum, calcium/silver, yttrium/silver, etc., of course, two or more layers of metal salts can be used in combination with the metal, such as lithium fluoride/ Aluminum, lithium fluoride/calcium/aluminum, barium fluoride/aluminum, and the like.

Typically, the anode is formed on a substrate, which may be a glass substrate or other flexible substrate. In one embodiment, the first electrode is an anode and the second electrode is a cathode.

In one embodiment, a flat layer is formed on the first electrode to provide a relatively flat layer to form a light-emitting layer in a subsequent step. The material of the flat layer is not particularly limited, and a flat layer can be formed using an existing material. In one embodiment, the planar layer is poly 3,4-ethylenedioxythiophene/polystyrenesulfonic acid (PEDOT:PSS).

When the flat layer is formed, the material of the flat layer can be laid on the first electrode by coating. Examples of coating include, but are not limited to, spin coating or blade coating, and the like. In one embodiment, the planar layer is formed on the first electrode by spin coating.

The luminescent layer may be selected from any luminescent material known in the art, such as Firpic (bis(4,6-difluorophenylpyridine-N, C2') pyridine formazan, respectively, as blue, green and red luminescent materials. Bis(4,6-difluorophenylpyridinato-N,C2)picolinate iridium), Ir(mppy) ₃ (parametric [2(p-tolyl)pyridine]iridium), and PER54 (tris[2-(p-tolyl)pyridine]iridium) It is purchased from 昱Ra photoelectric) and Hex-Ir(phq) ₃ (refer to [2-(4-n-hexylphenyl)quinoline)] 铱, Tris[2-(4-n-hexylphenyl)quinoline) iridium).

In one embodiment, the luminescent layer comprises a blue, green or red luminescent material. For example, the light-emitting layer includes Ir(mppy) ₃ as a green light-emitting material.

In one embodiment, the luminescent layer comprises PER54 or Hex-Ir(phq) ₃ as a red luminescent material.

In the organic light-emitting element of the present invention, the light-emitting layer includes 0.5% by weight to 10% by weight of the light-emitting material based on the total weight of the light-emitting layer. In one embodiment, the luminescent layer comprises 6 wt% Ir(mppy) ₃ based on the total weight of the luminescent layer.

In the organic light-emitting element of the present invention, the dual-host material includes both a hole transport material and an electron transport material.

In a specific embodiment, in the organic light emitting device of the present invention, the electricity The hole transporting material is selected from the group consisting of TCTA (4-carbazoyl-9-ylphenylamine), TASC (di-[4-(N, N-II) -p-tolylamino)phenyl]cyclohexane, Di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane), CBP (4,4'-bis(carbazole) -9-yl)biphenyl, 4,4'-Bis(carbazol-9-yl)biphenyl), SimCP2(bis[3,5-bis(9H-carbazol-9-yl)phenyl]diphenylnonane , Bis[3,5-di(9H-carbazol-9-yl)phenyl]diphenylsilane), TBCPF (9,9-bis(4,4'-bis(3,6-di-t-butylcarbazole)) Phenyl-9H-芴,9,9-di(4,4'-bis(3,6-Di-tert-butylcarbazole)-phenyl)-9H-fluorene), BIQF(6,60-(4,40- (9H-芴-9,9-diyl)bis(4,1-extended phenyl))bis(6H吲哚[2,3-b]quinoxaline, 6,60-(4,40-(9H -fluorene-9,9-diyl)bis(4,1-phenylene))bis(6Hindolo[2,3-b]quinoxaline) and BTCC-36(3,6-bis(3,6-di-fourth At least one of the group consisting of -9-oxazolyl-N-phenylcarbazole, 3,6-di-tert-butyl-9-carbazolyl-N-phenylcarbazole.

In one embodiment, the hole transport material is TCTA.

In one embodiment, the electron transporting material is selected from the group consisting of SPPO13 (2,7-bis(diphenylphosphoryloxy)-9,9'-cyclobiguanide, 2,7-Bis(diphenylphosphoryl)-9 , 9'-spirobifluorene), Dspiro-PO (bis(9,9'-cyclohexamidine-2-yl)-phenyl-phosphine oxide, Di(9,9-spirobifluoren-2-yl)-phenyl-phosphine Oxide), 26DCzPPy (2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine), TmPyPB (1,3,5-gin[(3-pyridyl)phenyl-3-yl]benzene, 1,3,5-Tri[(3-pyridyl)-phen-3-yl]benzene), ETM735 (purchased from 昱Ra photoelectric), DPyBPTz (2-(biphenyl-4-yl)-4,6-bis(4'-(pyridin-2-yl)biphenyl-4-yl)-1,3, 5-triphenylbenzene, 2-(biphenyl-4-yl)-4,6-bis(4'-(pyridin-2-yl)biphenyl-4-yl)-1,3,5-triazine) and PPT At least one of the group consisting of (2,8-bis(biphenylphosphino)dibenzo[b,d]thiophene, 2,8-Bis(diphenylphosphoryl)dibenzo[b,d]thiophene).

In one embodiment, the electron transporting material is SPPO13. The luminescent material, the hole transporting material and the electron transporting material of the present invention may be combined with each other for use in preparing an organic light emitting device. For example, in one embodiment, the luminescent layer comprises 6 wt% of Ir(mppy) ₃ , 31.2 Wt% TCTA and 62.8 wt% SPPO13.

In one embodiment, the weight ratio of the hole transport material to the electron transport material is 0.25 to 4.

In one embodiment, the weight ratio of the hole transport material to the electron transport material is 0.4968.

In one embodiment, the luminescent layer is formed on the planar layer by knife coating. The luminescent layer is formed on the flat layer by knife coating, for example, in accordance with the method described in Taiwan Patent No. 201123967.

According to the foregoing method, the present invention provides an organic light emitting device comprising: a first electrode; a flat layer formed on the first electrode; and a light emitting layer formed on the flat layer to sandwich the flat layer Between the first electrode and the light-emitting layer, wherein the light-emitting layer comprises a double-host material and a light-emitting material; and a second electrode is formed on the light-emitting layer, so that the light-emitting layer is sandwiched between the flat layer and the first layer Between the two electrodes.

In the organic light-emitting element of the present invention, the electrode may comprise a metal or metal substitute. The metal refers to a material containing a metal element or a material containing a metal alloy, wherein the metal alloy is a material containing two or more metals. Metal substitute refers to a metal having a metalloid nature, but is not generally known, such as a doped semiconductor or a transparent conductive oxide such as indium tin oxide (ITO). Typically, indium tin oxide is used as the anode. The cathode can usually be made of a layer of metal or two layers of metal such as calcium/aluminum, calcium/silver, yttrium/silver, etc., of course, two or more layers of metal salts can be used in combination with the metal, such as lithium fluoride/ Aluminum, lithium fluoride/calcium/aluminum, barium fluoride/aluminum, and the like.

In one embodiment, the first electrode is an anode and the second electrode is a cathode.

The material of the flat layer is not particularly limited, and a flat layer can be formed using an existing material. In one embodiment, the planar layer is poly 3,4-ethylenedioxythiophene/polystyrenesulfonic acid (PEDOT:PSS).

In the organic light-emitting element of the present invention, the light-emitting layer includes a double host material and a light-emitting material.

The luminescent layer may be selected from any luminescent material known in the art, such as Firpic, Ir(mppy) ₃ and PER54 (purchased from 昱Ra photoelectric) and Hex-Ir (phq) ₃ , respectively, as blue, green and red luminescent materials. .

In one embodiment, the luminescent layer comprises a blue, green or red luminescent material. For example, the light-emitting layer includes Ir(mppy) ₃ as a green light-emitting material.

In one embodiment, the luminescent layer comprises PER54 or Hex-Ir(phq) ₃ as a red luminescent material.

In the organic light-emitting element of the present invention, the light-emitting layer includes 0.5% by weight to 10% by weight of the light-emitting material based on the total weight of the light-emitting layer. In one embodiment, the luminescent layer comprises 6 wt% Ir(mppy) ₃ based on the total weight of the luminescent layer.

In the organic light-emitting element of the present invention, the dual-host material includes both a hole transport material and an electron transport material.

In one embodiment, the hole transport material is selected from at least one of the group consisting of TCTA, TAPC, CBP, SimCP2, TBCPF, BIQF, and BTCC-36.

In one embodiment, the hole transport material is TCTA.

In one embodiment, the electron transporting material is selected from at least one of the group consisting of SPPO13, Dspiro-PO, 26DCzPPy, TmPyPB, ETM735, DPyBPTz, and PPT.

In one embodiment, the electron transporting material is SPPO13. The luminescent material, the hole transporting material and the electron transporting material of the present invention may be combined with each other for use in preparing an organic light emitting device. For example, in one embodiment, the luminescent layer comprises 6 wt% of Ir(mppy) ₃ , 31.2 Wt% TCTA and 62.8 wt% SPPO13.

In the organic light emitting device of the present invention, the hole transmission material and the electricity The weight ratio of the sub-transport material is 0.25 to 4.

In one embodiment, the weight ratio of the hole transport material to the electron transport material is 0.5.

As shown in FIG. 1 , the organic light emitting device 10 of the present invention includes a first electrode 110; a flat layer 120 is formed on the first electrode 110; and a light emitting layer 130 is formed on the flat layer 120. The flat layer 120 is interposed between the first electrode 110 and the light emitting layer 130; and the second electrode 140 is formed on the light emitting layer 130 such that the light emitting layer 130 is sandwiched between the flat layer 120 and the second layer Between the electrodes 140.

The invention is illustrated by the following examples of organic light-emitting elements of different layer structures, but the materials, thicknesses and concentrations used in the various layers are not intended to limit the scope of the invention.

Example 1 Preparation of Single-Layer Organic Light-Emitting Element

A flat layer of a thickness of about 30 to 60 (nm) nm and a material of PEDOT:PSS (Model: AI4083) was spin-coated on the etched ITO substrate, followed by placing a hot plate to anneal at 80 ° C for 10 to 20 minutes. Coating the luminescent layer on the flat layer with a doctor blade at a coating speed of about 100 to 500 cm/sec (cm/s) to form a luminescent layer having a thickness of about 40 to 90 nm, and then placing a hot plate at 80 ° C for 10 minutes, wherein The material ratio of the light-emitting layer was 31.2 wt% TCTA: 62.8 wt% SPPO13: 6% wt% Ir(mppy) ₃ . Then, the substrate is placed in a vapor deposition electrode of the vapor deposition machine. In this embodiment, LiF having a thickness of about 1 nm to 3 nm is first deposited, and Al having a thickness of about 100 nm is evaporated, and finally, a single layer structure can be obtained by encapsulation. Organic light-emitting element.

Example 2 Preparation of Three-Layer Structure Organic Light-Emitting Element

A flat layer of a thickness of about 30 to 60 (nm) nm and a material of PEDOT:PSS (Model: AI4083) was spin-coated on the etched ITO substrate, followed by placing a hot plate to anneal at 80 ° C for 10 to 20 minutes. Applying a scraper coating material to the hole transport layer of the TCTA on the flat layer, the coating speed is about 100 to 500 cm/s, to form a hole transport layer having a thickness of about 30 nm, and then placing the hot plate to anneal at 80 ° C for 10 minutes. The light-emitting layer is coated on the hole transport layer by a doctor blade at a coating speed of about 100 to 500 cm/s to form a light-emitting layer having a thickness of about 40 nm to 90 nm. The material ratio of the light-emitting layer is 31.2 wt% TCTA: 62.8 wt%. SPPO13: 6wt% Ir(mppy) ₃ . The hot plate was placed and annealed at 80 ° C for 10 minutes. An electron transport layer of SPPO13 was coated on the light-emitting layer with a doctor blade at a coating speed of about 100 to 500 cm/s to form an electron transport layer having a thickness of about 40 nm to 90 nm. Next, the substrate is placed in a vapor deposition electrode of the vapor deposition machine. In this embodiment, LiF having a thickness of about 1 nm to 3 nm is first deposited, and Al having a thickness of about 100 nm is evaporated, and finally, a three-layer structure can be obtained by packaging. Organic light-emitting element.

Test Example 1 Luminous lifetime of organic light-emitting elements of different layers

A constant current is supplied to continuously illuminate the element at a specific brightness of 100 nits (Nit, Cd/m ² ), and the change in luminance attenuation of each element is observed and each element T50 is measured. When the brightness of the component is attenuated to 50% (ie, 100 Nit decays to 50 Nit), it is the component T50, which is the luminescence lifetime of the component.

Figure 2 shows the luminescence lifetime of an organic light-emitting element comprising different numbers of layers. It can be seen from the figure that there is a single layer of light-emitting layer structure under the same luminous intensity. The component T50 of the organic light-emitting element was 140 hours, and the component T50 of the organic light-emitting element having a three-layer light-emitting layer structure was only 13 hours. Therefore, the organic light-emitting element of the present invention having a single-layer light-emitting layer structure has a significantly better light-emitting lifetime.

10‧‧‧Organic light-emitting elements

110‧‧‧First electrode

120‧‧‧flat layer

130‧‧‧Lighting layer

140‧‧‧second electrode

Claims (18)

An organic light-emitting element comprising: a first electrode; a flat layer formed on the first electrode; and a light-emitting layer formed on the flat layer, the flat layer being sandwiched between the first electrode and the light-emitting layer The light-emitting layer includes a dual-host material and a light-emitting material; and a second electrode is formed on the light-emitting layer such that the light-emitting layer is sandwiched and contacted between the flat layer and the second electrode. The organic light-emitting element according to claim 1, wherein the light-emitting layer comprises 0.5% by weight to 10% by weight of the light-emitting material based on the total weight of the light-emitting layer. The organic light-emitting device of claim 1, wherein the dual-host material comprises a hole transport material and an electron transport material. The organic light-emitting device of claim 3, wherein the hole transporting material is selected from the group consisting of ginseng (4-carbazolyl-9-ylphenyl)amine (TCTA), (di-[4-( N,N-di-p-tolylamino)phenyl]cyclohexane (TAPC), 4,4'-bis(carbazol-9-yl)biphenyl (CBP), (double [3,5- Bis(9H-carbazol-9-yl)phenyl]diphenylnonane (SimCP2), 9,9-bis(4,4'-bis(3,6-di-t-butylcarbazole)phenyl -9H-芴(TBCPF), 6,60-(4,40-(9H-芴-9,9-diyl)bis(4,1-extended phenyl))bis(6H吲哚[2,3- b] in the group consisting of quinoxaline (BIQF) and 3,6-bis(3,6-di-tetrabutyl-9-carbazolyl)-N-phenylcarbazole (BTCC-36) At least one. An organic light-emitting element according to claim 3, wherein the The electron transporting material is selected from the group consisting of 2,7-bis(diphenylphosphoryloxy)-9,9'-cyclocyclic guanidine (SPPO13), bis(9,9'-cyclocyclobiguan-2-yl)- Phenyl-phosphine oxide (Dspiro-PO), 2,6-bis(3-(9H-carbazol-9-yl)phenylpyridine (26DCzPPy), 1,3,5-gin[(3-pyridyl) Benz-3-yl]benzene (TmPyPB), (2-(biphenyl-4-yl)-4,6-bis(4'-(pyridin-2-yl)biphenyl-4-yl)-1,3 At least one of a group consisting of 5-triazabenzene (DPyBPTz) and 2,8-bis(biphenylphosphinooxy)dibenzo[b,d]thiophene (PPT). The organic light-emitting device of claim 3, wherein the hole transport material and the electron transport material have a weight ratio of 0.25 to 4. The organic light-emitting device of claim 1, wherein the light-emitting layer comprises a blue, green or red light-emitting material. The organic light-emitting device according to claim 1, wherein the flat layer is formed of poly 3,4-ethylenedioxythiophene/polystyrenesulfonic acid (PEDOT:PSS). A method of fabricating an organic light-emitting device, comprising: forming a planar layer on a first electrode; forming a light-emitting layer on the planar layer, the flat layer being sandwiched between the first electrode and the light-emitting layer, wherein the light-emitting layer The layer includes a dual host material and a luminescent material; and a second electrode is formed on the luminescent layer such that the luminescent layer is sandwiched and contacted between the flat layer and the second electrode. The method of claim 9, wherein the luminescent layer comprises 0.5 wt% to 10 wt% of the luminescent material based on the total weight of the luminescent layer. material. The method of claim 9, wherein the dual host material comprises a hole transport material and an electron transport material. The method of claim 11, wherein the hole transporting material is selected from the group consisting of ginseng (4-carbazolyl-9-ylphenyl)amine (TCTA), (di-[4-(N, N-di-p-tolylamino)phenyl]cyclohexane (TAPC), 4,4'-bis(carbazol-9-yl)biphenyl (CBP), (double [3,5-di() 9H-carbazol-9-yl)phenyl]diphenylnonane (SimCP2), 9,9-bis(4,4'-bis(3,6-di-t-butylcarbazole)phenyl-9H -芴(TBCPF), 6,60-(4,40-(9H-芴-9,9-diyl)bis(4,1-extended phenyl))bis(6H吲哚[2,3-b] At least one of a group consisting of quinoxaline (BIQF) and 3,6-bis(3,6-di-tetrabutyl-9-carbazolyl)-N-phenylcarbazole (BTCC-36) By. The method of claim 11, wherein the electron transporting material is selected from the group consisting of 2,7-bis(diphenylphosphino)-9,9'-cyclocyclic guanidine (SPPO13), two ( 9,9'-cyclocyclobisindol-2-yl)-phenyl-phosphine oxide (Dspiro-PO), 2,6-bis(3-(9H-carbazol-9-yl)phenylpyridine (26DCzPPy) 1,3,5-epi[(3-pyridyl)phenyl-3-yl]benzene (TmPyPB), (2-(biphenyl-4-yl)-4,6-bis(4'-(pyridine- 2-yl)biphenyl-4-yl)-1,3,5-triazabenzene (DPyBPTz) and 2,8-bis(biphenylphosphinooxy)dibenzo[b,d]thiophene (PPT) At least one of the group consisting of. The method of claim 11, wherein the hole transporting material and the electron transporting material have a weight ratio of 0.25 to 4. The method of claim 9, wherein the luminescent layer comprises a blue, green or red luminescent material. The method of claim 9, wherein the flat layer is formed of poly 3,4-ethylenedioxythiophene/polystyrenesulfonic acid (PEDOT:PSS). The method of claim 9, wherein the flat layer is formed by spin coating on the first electrode. The method of claim 9, wherein the luminescent layer is formed by doctor blade coating on the flat layer.