KR20220078505A - Perovskite light-emitting device having passivation layer and fabrication method thereof - Google Patents

Abstract

Disclosed is a perovskite light emitting device in which the defects of the perovskite thin film are reduced. The passivation layer in the perovskite light emitting device is formed on the top of the perovskite thin film to remove the defects of the perovskite nanocrystal grains and to solve the charge imbalance in the device, including the perovskite thin film The maximum efficiency and maximum brightness of the light emitting device are improved.

Description

Perovskite light-emitting device including passivation layer and manufacturing method thereof

The present invention relates to a perovskite light emitting device, and more particularly, to a perovskite light emitting device in which defects of the perovskite thin film are reduced by forming a passivation layer on the perovskite thin film.

Recently, the center of the display is shifting from liquid crystal displays to organic light emitting diodes. Organic light emitting diode (OLED) devices are based on organic light emitting materials, and inorganic quantum dot LEDs with improved color purity are being actively researched and developed as other alternatives. However, both the organic light-emitting body and the inorganic quantum dot light-emitting body have intrinsic limitations in terms of materials.

Conventional organic light emitting materials have high efficiency, but have a wide spectrum and thus have poor color purity. In addition, although inorganic quantum dot light emitting materials have been known to have good color purity, since light emission is caused by quantum confinement effect or quantum size effect, the emission color is mainly dependent on the size of nanoparticles having a diameter of 10 nm or less. is changed, and it is difficult to control the quantum dot size to be uniform as it goes toward blue color, so there is a problem in that color purity is lowered. Moreover, since inorganic quantum dots have a very deep valence band, there is a problem in that hole injection is difficult because the hole injection barrier in the organic hole injection layer is very large. In addition, the organic light emitting material and the inorganic quantum dot light emitting material has a disadvantage in that it is expensive.

Therefore, there is a demand for a new organic/inorganic hybrid light-emitting body that compensates for the disadvantages of the organic light-emitting material and the inorganic quantum dot light-emitting material and maintains the advantages.

On the other hand, organic/inorganic hybrid materials have the advantages of low manufacturing cost, simple manufacturing and device manufacturing processes, easy to control optical and electrical properties, and inorganic materials with high charge mobility and mechanical and thermal stability. Because it can have all the advantages, it is in the spotlight both academically and industrially.

Among them, metal halide perovskite material has high color purity, color control is simple, and synthesis cost is low, so the development potential as a light emitting material is very high. In addition, since it has a high color purity (Full width at half maximum (FWHM) ≒ 20 nm), it is possible to implement a light emitting device closer to natural color.

In a metal halide perovskite ABX ₃ structure, an organic ammonium (RNH ₃ ) cation or metal cation is located at the A site, and halide anions (Cl ^- , Br ^- , I ^- ) are located at the X site. Since the lobskite material is formed, the composition is completely different from the inorganic metal oxide perovskite material.

In addition, according to the difference in these constituent materials, the properties of the material also vary. Inorganic metal oxide perovskite typically exhibits characteristics such as superconductivity, ferroelectricity, and colossal magnetoresistance.

On the other hand, metal halide perovskite is similar to a lamellar structure in that organic or alkali metal planes and inorganic planes are alternately stacked, so excitons can be bound in the inorganic plane. It can be an ideal light emitting body that emits light of very high color purity.

Even if it is an organic/inorganic hybrid perovskite (ie, organometallic halide perovskite) among metal halide perovskite materials, organic ammonium is a chromophore with a smaller band gap than the central metal and halogen crystal structure (BX ₃ ) In the case of including a chromophore (mainly including a conjugated structure), light of high color purity cannot be emitted because light emission occurs from organic ammonium, so that the full width at half maximum of the emission spectrum becomes wider than 50 nm, making it unsuitable as a light emitting layer. Therefore, in this case, it is not very suitable for the high color purity light emitting body emphasized in this patent. Therefore, it is important that organic ammonium does not contain a chromophore and that light emission occurs in an inorganic lattice composed of a central metal-halogen element in order to produce a light-emitting material with high color purity. That is, this patent is focused on the development of a high-purity, high-efficiency light-emitting body that emits light from an inorganic lattice.

For example, Korean Patent Laid-Open No. 10-2001-0015084 (2001.02.26) discloses an electroluminescent device in which a dye-containing organic-inorganic hybrid material is formed in the form of a thin film rather than a particle and used as a light emitting layer. There is no light emission from the lobskite lattice structure.

However, since the metal halide perovskite has a small exciton binding energy, it is possible to emit light at low temperatures, but at room temperature, due to thermal ionization and delocalization of charge carriers, excitons do not go to light emission and are separated into free charges and disappear. . In addition, when free charges recombine to form excitons, there is a problem in that the excitons are annihilated by the surrounding high conductivity layer, so that light emission cannot occur.

Perovskite nanocrystal particles with improved properties that can be applied to various electronic devices show improved luminous efficiency by confining excitons to a very small size. Also, a bulk polycrystalline film having a very small grain size of 100 nm or less may exhibit improved luminous efficiency through exciton confinement. In addition, exciton confinement can occur well in perovskite nanocrystal particles having a size of several nm to several tens of nm, so that nanocrystal particles in the 3 nm-20 nm region show high luminous efficiency. However, the perovskite light emitting layer exhibits relatively low light emitting efficiency due to the presence of surface defects, and exhibits low light emitting efficiency by causing charge carrier imbalance in the light emitting device.

Accordingly, there is a need for a method capable of eliminating the defects of the perovskite thin film and resolving the charge imbalance in the light emitting device.

A first object of the present invention is to provide a light emitting device including a passivation layer that can reduce the defects of the perovskite thin film and solve the charge imbalance.

A second object of the present invention is to provide a method of manufacturing a light emitting device including the passivation layer.

In order to achieve the first object, the present invention provides a substrate; a first electrode positioned on the substrate; a perovskite thin film positioned on the first electrode; a passivation layer disposed on the perovskite thin film and comprising the following passivation material (1) or (2); and a second electrode positioned on the passivation layer.

The passivation material (1) includes an organic material or compound represented by the following formula (1).

[Formula 1]

In Formula 1, R ₁ , R ₃ or R ₅ is an alkyl group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms or a heteroalke a nyl group, an aryl group or aryloxy group having 6 to 30 carbon atoms, or a heteroaryl group having 2 to 30 carbon atoms, R ₂ , R ₄ or R ₆ is a halogen or a halogenated alkyl group having 1 to 10 carbon atoms, 2 to 10 carbon atoms a halogenated alkenyl group or a halogenated alkynyl group.

The passivation material (2) is a compound represented by the following Chemical Formula 2, Chemical Formula 3 or Chemical Formula 4; and an organic material comprising at least one selected from organic semiconductors and polymers; and a mixture of mixtures thereof.

[Formula 2]

In Formula 2, a ¹ to a ⁶ are each independently an alkyl group or alkoxy group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group or cycloalkenyl group having 3 to 10 carbon atoms, halogen, carbon number an alkenyl or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group or heteroalkenyl group having 3 to 10 carbon atoms, or an aryl group or aryloxy group having 6 to 30 carbon atoms.

[Formula 3]

In Formula 3, X is a halogen element, and n is an integer of 1 to 100.

[Formula 4]

In Formula 4, X is a halogen element, and n is an integer of 1 to 100.

Also preferably, the passivation layer may include a compound of Formula 5 below.

[Formula 5]

In Formula 5, X ₁ , X ₂ or X ₃ is F, Cl, Br, or I.

Also preferably, the X ₁ , X ₂ and X ₃ may be the same halogen element.

Also preferably, the mixture of (2) is a compound represented by Formula 2, Formula 3 or Formula 4; and an organic material comprising at least one selected from organic semiconductors and polymers; 1: 0.7 to 1.4 molar ratio.

Also preferably, a hole injection layer or an electron transport layer may be further included between the first electrode and the perovskite thin film or between the passivation layer and the second electrode.

Also preferably, the perovskite thin film comprises perovskite nanocrystal particles, and the perovskite nanocrystal particles are bonded to the perovskite nanocrystal and the perovskite nanocrystal surface. Organic ligands may be included.

Also preferably, the perovskite nanocrystal particles may have a core-shell structure.

Also preferably, the perovskite nanocrystal particles may have a gradient composition.

Also preferably, the perovskite nanocrystal particles may be doped with n-type or p-type.

Also preferably, the perovskite nanocrystal particles may have a diameter larger than the exciton bore diameter.

In addition, in order to achieve the second object, the present invention comprises the steps of forming a first electrode on the substrate; forming a perovskite thin film on the first electrode; forming a passivation layer comprising the following passivation layer material (1) or (2) on the perovskite thin film; And it provides a method of manufacturing a perovskite light emitting device comprising the step of forming a second electrode on the passivation layer.

The passivation material (1) includes an organic material or compound represented by the following formula (1).

[Formula 1]

In Formula 1, R ₁ , R ₃ or R ₅ is an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms Or a heteroalkenyl group, an aryl group or aryloxy group having 6 to 30 carbon atoms, or a heteroaryl group having 2 to 30 carbon atoms, R ₂ , R ₄ or R ₆ is a halogen or a halogenated alkyl group having 1 to 10 carbon atoms, 2 carbon atoms to 10 halogenated alkenyl groups or halogenated alkynyl groups.

The passivation material (2) is a compound represented by the following Chemical Formula 2, Chemical Formula 3 or Chemical Formula 4; and an organic material comprising at least one selected from organic semiconductors and polymers; and a mixture of mixtures thereof.

[Formula 2]

In Formula 2, a ¹ to a ⁶ are each independently an alkyl group or alkoxy group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, cycloalke having 3 to 10 carbon atoms. Nyl group or heteroalkenyl group, aryl group or aryloxy group having 6 to 30 carbon atoms, heteroaryl group having 2 to 30 carbon atoms, halogen, halogenated alkyl group having 1 to 10 carbon atoms, halogenated alkenyl group having 2 to 10 carbon atoms or halogenated It is an alkynyl group.

[Formula 3]

In Formula 3, X is a halogen element, and n is an integer of 1 to 100.

[Formula 4]

In Formula 4, X is a halogen element, and n is an integer of 1 to 100.

Also preferably, the perovskite thin film may be formed through spin coating.

Also preferably, the formation of the perovskite thin film comprises the steps of introducing a perovskite nanocrystalline particle solution on the first electrode; Giving a holding time (waiting time) or drying time (drying time) to the introduced perovskite nanocrystalline particle solution; and after the holding time is over, applying the perovskite nanocrystal particle solution through a spin coater to perform spin coating.

Also preferably, the holding time may be 2 minutes to 25 minutes.

Also preferably, the perovskite thin film may be formed through bar coating.

Also preferably, the bar coating may include: introducing a perovskite nanocrystal particle solution on the first electrode; tilting the first electrode into which the perovskite nanocrystal solution is introduced by giving an inclination angle with respect to the horizontal plane; and performing bar coating on the inclined first electrode and the perovskite nanocrystalline particle solution.

Also preferably, a holding time may be given after the step of introducing the perovskite nanocrystal particle solution.

Also preferably, the passivation layer may include a compound of Formula 5 below.

[Formula 5]

In Formula 5, X ₁ , X ₂ or X ₃ is F, Cl, Br, or I.

Also preferably, the X ₁ , X ₂ and X ₃ may be the same halogen element.

The passivation layer in the perovskite light emitting device according to the present invention is formed on the top of the perovskite thin film to remove the defects of the perovskite nanocrystal particles and to solve the charge imbalance in the device, the perovskite The maximum efficiency and maximum luminance of a light emitting device including a thin film are improved.

The technical effects of the present invention are not limited to those mentioned above, and other technical effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a cross-sectional view showing a perovskite light emitting device according to the present invention.
Figure 2 is a schematic diagram of the crystal structure of the metal halide perovskite constituting the perovskite thin film in the perovskite light emitting device according to the present invention.
Figure 3 is a schematic diagram showing the difference between the metal halide perovskite nanocrystalline particle emitter and the metal halide perovskite bulk (Bulk) polycrystalline thin film.
4 is a schematic diagram showing a metal halide perovskite nanocrystal particle light emitting body constituting a perovskite thin film in the perovskite light emitting device according to the present invention.
5 is a schematic diagram showing a method of manufacturing a metal halide perovskite nanocrystal particle light emitting body constituting a perovskite thin film in the perovskite light emitting device according to the present invention.
6 is a schematic diagram showing the metal halide perovskite nanocrystal particles of the core-shell structure constituting the perovskite thin film and the energy band diagram thereof in the perovskite light emitting device according to the present invention.
7 is a schematic diagram showing a method of manufacturing a metal halide perovskite nanocrystal particle having a core-shell structure constituting a perovskite thin film in the perovskite light emitting device according to the present invention.
8 is a schematic diagram showing metal halide perovskite nanocrystal particles having a gradient composition structure constituting a perovskite thin film in the perovskite light emitting device according to the present invention.
9 is a schematic diagram showing a metal halide perovskite nanocrystal particle having a gradient composition structure constituting a perovskite thin film and an energy band diagram thereof in the perovskite light emitting device according to the present invention.
10 is a schematic diagram showing doped perovskite nanocrystal particles constituting a perovskite thin film and an energy band diagram thereof in the perovskite light emitting device according to the present invention.
11 is a cross-sectional view for explaining a method of manufacturing a perovskite light emitting device according to the present invention.
12 is a schematic diagram for explaining a mechanism in which defects in a perovskite thin film are healed by a passivation layer according to a preferred embodiment of the present invention.
13 is a graph showing the external quantum efficiency according to Measurement Example 1 of the present invention.
14 is a graph illustrating capacitance-temperature characteristics of light emitting devices according to Measurement Example 2 of the present invention.
15 is a graph illustrating an external quantum efficiency-voltage characteristic and an electrical efficiency-voltage characteristic according to Measurement Example 3 of the present invention.
16 is a schematic diagram of forming a perovskite light emitting layer by giving a holding time according to Measurement Example 4 of the present invention.
17 is an SEM image of the perovskite light emitting layer according to the holding time according to Measurement Example 4 of the present invention.
18 is a graph showing the light emission and absorbance of the perovskite light emitting layer according to the holding time according to Measurement Example 4 of the present invention.
19 is a graph measuring the electrical efficiency of the perovskite light emitting layer according to the holding time according to Measurement Example 4 of the present invention.
20 is a schematic diagram for explaining a ligand removal process according to Preparation Example 3 of the present invention.
21 is a graph showing FTIR data of a perovskite light emitting layer in light emitting devices according to Measurement Example 5 of the present invention.
22 is a graph illustrating current densities of light emitting devices according to Measurement Example 5 of the present invention.
23 is a graph illustrating electrical efficiency and luminance of light emitting devices according to Measurement Example 5 of the present invention.
24 is a schematic diagram for explaining a bar coating applied to form a perovskite light emitting layer according to Preparation Example 4 of the present invention.
25 is a graph and an image of measuring photoluminescence distribution according to Measurement Example 6 of the present invention.
26 is a SEM image showing the surface uniformity of the light emitting layer according to Measurement Example 6 of the present invention.
27 is an AFM image showing the surface uniformity of the light emitting layer according to Measurement Example 6 of the present invention.
28 is a graph illustrating external quantum efficiency and luminance characteristics of a light emitting device according to Measurement Example 6 of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

While the invention is susceptible to various modifications and variations, specific embodiments thereof are illustrated and illustrated in the drawings and will be described in detail hereinafter. However, it is not intended to limit the invention to the particular form disclosed, but rather the invention includes all modifications, equivalents and substitutions consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element, such as a layer, region, or substrate, is referred to as being “on” another component, it may be directly on the other element or intervening elements in between. .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and/or regions, such elements, components, regions, layers and/or regions are not It will be understood that they should not be limited by these terms.

The present invention provides a perovskite light emitting device comprising a passivation layer.

Here, the light emitting device refers to a device that converts an electronic signal into light, and includes a light emitting diode, a light emitting transistor, a laser, a polarized light emitting device, etc. It may include a device that emits light.

The perovskite light emitting device according to the present invention is a light emitting device comprising a perovskite thin film as a light emitting layer, and a passivation layer is formed on the perovskite thin film.

1 is a cross-sectional view showing a perovskite light emitting device of the present invention.

First, referring to FIG. 1 ( a ), the perovskite light emitting device according to the present invention is a substrate 10 , a first electrode 20 , a perovskite thin film 30 , and a passivation layer 40 . and a second electrode 50 .

The substrate 10 serves as a support for the light emitting device, and is made of a transparent material. In addition, the substrate 10 may use both a flexible material and a hard material, but it is more preferable to be formed of a flexible material. The substrate 10 may be made of a light-transmitting glass, ceramic material, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI) or polypropylene (PP). can However, the present invention is not limited thereto, and the substrate may be a metal substrate capable of reflecting light.

A first electrode 20 may be positioned on the substrate 10 .

The first electrode 20 is an electrode (anode) into which holes are injected, and is made of a conductive material. The material constituting the first electrode 20 may be a conductive metal oxide, a metal, a metal alloy, or a carbon material. Conductive metal oxides include indium tin oxide (ITO), fluorine tin oxide (FTO), antimony tin oxide (ATO), fluorine doped tin oxide (FTO), SnO ₂ , ZnO , or a combination thereof. Suitable metals or metal alloys as an anode may be Au and CuI. The carbon material may be graphite, graphene, or carbon nanotubes.

If the light emitting device is a light emitting diode, and when a conductive polymer is used as the first electrode 20 , the perovskite thin film is a light emitting layer without additional deposition of a hole injection layer on the first electrode 20 . can be formed. On the other hand, when an electrode other than the conductive polymer is used as the first electrode 20 , it may be necessary to introduce a hole injection layer on the first electrode 20 .

Subsequently, the perovskite thin film 30 may be positioned on the first electrode 20 .

The perovskite thin film 30 serves as a light emitting layer in the light emitting device of the present invention, and may be made of organic/inorganic hybrid perovskite or inorganic metal halide perovskite.

A passivation layer 40 is disposed on the perovskite thin film 30 .

The passivation layer comprises the following passivation material (1) or (2).

Passivation material (1): a compound represented by the following formula (1)

[Formula 1]

In Formula 1, R ₁ , R ₃ or R ₅ is an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group or cycloalkenyl group having 3 to 10 carbon atoms, or a cycloalkenyl group having 6 to 10 carbon atoms It may be an aryl group or aryloxy group having 30, or a heteroaryl group having 2 to 30 carbon atoms. In this case, the “alkyl group” refers to a hydrocarbon consisting of a single bond, the “alkenyl group” refers to a hydrocarbon containing at least one double bond in the structure, and the “alkynyl group” refers to a triple bond in the structure. bond), the "cycloalkyl group" is an aromatic hydrocarbon consisting of a single bond, the "cycloalkenyl group" is an aromatic hydrocarbon containing at least one double bond, and the "aryl group" is an aromatic hydrocarbon A functional group by removing one hydrogen atom from In the case of an aryl group (or ring) containing 1 to 4 heteroatoms selected from N, O and S (in each separate ring), the "halogenation" means at least one halogen in the structure.

wherein R ₂ , R ₄ or R ₆ is a halogen or a halogenated alkyl group having 1 to 10 carbon atoms, a halogenated alkenyl group having 2 to 10 carbon atoms, or a halogenated alkynyl group. However, more preferably, the R ₁ , R ₃ or R ₅ is CH ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ or a phenyl group, and R ₂ , R ₄ or R ₆ is X, CH ₂ X, C ₂ H ₄ X or C ₃ H ₆ X, and X is F, Cl, Br, or I more preferably in terms of external quantum efficiency improvement and the like.

In particular, the passivation layer 40 can heal the surface defects of the perovskite thin film 30 functioning as a light emitting layer by including the compound of Formula 5 below.

[Formula 5]

In Formula 5, X ₁ , X ₂ or X ₃ is F, Cl, Br, or I. In addition, it is preferable that X ₁ , X ₂ and X ₃ are the same halogen elements.

Passivation material (2): a compound containing a halogen group; and an organic material; a mixture of

The mixture includes a compound containing a halogen group and an organic material.

First, the compound including a halogen group means a compound including at least one halogen group in its structure, and more specifically, includes a compound represented by Formula 2, Formula 3, or Formula 4 below.

[Formula 2]

In this case, in Formula 2, a ¹ to a ⁶ are each independently an alkyl group or alkoxy group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group or cycloalkenyl group having 3 to 10 carbon atoms, and a cycloalkenyl group having 3 to 10 carbon atoms. It may be an aryl group or aryloxy group having 6 to 30 carbon atoms, a heteroaryl group having 2 to 30 carbon atoms, halogen, a halogenated alkyl group having 1 to 10 carbon atoms, a halogenated alkenyl group having 2 to 10 carbon atoms, or a halogenated alkynyl group. Preferably, a ¹ , a ³ or a ⁵ is H, CH ₃ , C ₂ H _{5 ,} C ₃ H _{7 ,} C ₄ H ₉ or a phenyl group, and a ² , a ⁴ or a ⁶ is X, CH ₂ X, C ₂ H ₄ X or C ₃ H ₆ X, X is F, Cl, Br or I.

[Formula 3]

In this case, in Formula 3, X is a halogen element, and n is an integer of 1 to 100.

[Formula 4]

In this case, in Formula 4, X is a halogen element, and n is an integer of 1 to 100.

Also more preferably, the compound containing the halogen group is 1,3,5-tris(bromomethyl)-2,4,6-triethylbenzene (TBTB), (1,3,5-tris(bromo) methyl)benzene), 2,4,6-tris(bromomethyl)mesitylene (TBMM), 1,2,4,5-tetrakis(bromomethyl)benzene, hexakis(bromomethyl)benzene, poly (pentabromophenyl methacrylate), poly(pentabromobenzyl methacrylate), poly(pentabromobenzyl acrylate), poly(4-bromostyrene) and poly(4-vinylpyridinium tri bromide), and more preferably 2,4,6-tris(bromomethyl)mesitylene (TBMM).

Meanwhile, the compound and organic material including the halogen group may include at least one selected from organic semiconductors and polymers. The organic semiconductor and polymer added here can improve dispersion of compounds and organic substances containing halogen groups, can control affinity (or adhesion, coatability, etc.) at the interface with the surface of the lower layer, and can control the charge balance in the device. have.

First, the organic semiconductor contains at least one aromatic hydrocarbon, has a mobility of 10 ^-8 cm ² /Vs or more, and an optical bandgap (measured by the right-most onset value of the UV/Vis spectrum) of 1.0 eV to It refers to a material exhibiting a value between 6.0 eV.

Specifically, the organic semiconductor is tris(8-quinolinolate)aluminum {Tris-(8-hydroxyquinoline)aluminum, Alq3}, 3-(4-biphenylyl)-4-phenyl-5-tert-butyl Phenyl-1,2,4-triazole {3- (4-Bipenylyl) -4-phenyl-5-tert-butylphenyl-1, 2, 4-triazole ,TAZ}, tris-phenylquinoxaline 1,3, 5-tris[(3-phenyl-6-trifluoromethyl)quinoxalin-2-yl]benzene{Tris-Phenylquinoxalines 1,3,5-tris[(3-phenyl-6-trifluoromethyl)quinoxaline-2-yl ]benzene, TPQ1}, tris-phenylquinoxaline 1,3,5-tris[{3-(4-tert-butylphenyl)-6-trifluoromethyl}quinoxalin-2-yl]benzene {Tris- Phenylquinoxalines 1,3,5-tris[{3-(4-tert-butyl)-6-trifluoromethyl}quinoxaline-2-yl]benzene, TPQ2}, 4,7-diphenyl-1,10-phenanthroline ( 4,7-diphenyl-1,10-phenanthroline, Bphen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroline , BCP), 10-benzo [h] quinolinol-beryllium (10-benzo [h] quinolinol-beryllium, BeBq2), 8-hydroxy-2-methylquinoline- (4-phenylphenoxy) aluminum {(Bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum, BAlq}, 4,4'-N,N'-dicarbazole-biphenyl (4,4'-N,N'-Dicabazol) -biphenyl, CBP), 9,10-di (naphthalene-2-yl) anthracene) {9,10-di (naphthalene-2-yl) anthracene, AND}, 4, 4', 4"-tris (N- Carbazolyl) triphenylamine {4, 4', 4''-Tris (N-cabazolyl) triphenylamine, TCTA}, 1,3,5-t Lys(N-phenylbenzimidazol-2-yl)benzene {1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene, TPBI}, 3-tert-butyl-9,10-di(naphth -2-yl) anthracene (TBADN) (1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-diyl)tris(diphenylphosphine oxide),2,4 ,6-tris[3-diphenylphosphinyl]phenyl]-1,3,5-triazine (PO-T2T), tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl) Borane (3TPYMB), 4,6-bis(3,5-di(pyridin-3-yl)phenyl)-2-methylpyrimidine (B3PYMPM) and 2-[4-(9,10-di-naphthalene- 2-yl-anthracen-2-yl)-phenyl]-1-phenyl-1H-benzoimidazole (ZADN) may include at least one selected from, preferably one selected from TPBI, PO-T2T and ZADN It may include more than one species, and more preferably include one or more selected from TPBI and ZADN.

In addition, the polymer is poly(methyl methacrylate) {Poly(Methyl Methacrylate, PMMA), poly(ethyl methacrylate) {Poly(ethyl methacrylate), PEMA}, poly(butyl methacrylate) {Poly(butyl methacrylate) , PBMA), poly(2-ethyl-2-oxazoline, PEOXA}, at least one selected from polyacrylamide (Polyacrylamide PAM) and polyethylene oxide (PEO) may include, and preferably may include at least one selected from PMMA, PEOXA and PEO, and more preferably include at least one selected from PMMA and PEO.

On the other hand, the mixture may include a compound and organic material containing a halogen group in a molar ratio of 1.0: 0.3 to 1.0: 10.0, preferably 1.0: 0.7 to 1.0: 1.5, in a molar ratio compared to the organic semiconductor and polymer to be added. have. At this time, when the compound and organic material containing the halogen group are included in less than 0.3 molar ratio, there may be a problem that the defect passivation effect by the halogen compound and the organic material may be insignificant, and if it exceeds 10.0 molar ratio, it is added There may be a problem in that the dispersion effect of organic semiconductors and polymers to be used is greatly reduced.

Through the above-described structure, the perovskite light emitting device has a perovskite thin film in which surface defects are healed, and high external quantum efficiency and current efficiency can be secured.

In addition, it is possible to obtain the effect of improving the external quantum efficiency of the light emitting device through the action of simultaneously performing electron injection promotion and perovskite defect healing by mixing the compound containing the above-described halogen group with an organic material.

A second electrode is formed on the passivation layer 40 .

On the other hand, referring to Figures 1 (b) and 1 (c), in the perovskite light emitting device according to the present invention, the passivation layer 40 is the perovskite thin film 30 in Figure 1-1 Instead of entering between the first electrode 20 and the second electrode 50, the passivation material (1) or (2) may be formed between the first electrode 20 and the perovskite thin film 30 using an organic material and/or compound. Also, in order to realize a more perfect passivation effect depending on the perovskite thin film material used, the passivation layer 40 is formed between the perovskite thin film 30 and the second electrode 50 as shown in FIGS. 1-3. and the first electrode 20 and the perovskite thin film 30 may be simultaneously formed.

2 is a structure of a metal halide perovskite nanocrystal according to the present invention.

Figure 2 shows the structures of organic/inorganic hybrid perovskite nanocrystals and inorganic metal halide perovskite nanocrystals together.

Referring to FIG. 2 , this organic/inorganic hybrid perovskite nanocrystal has a central metal in the center, and six inorganic halide materials (X) are formed on all surfaces of the hexahedron in a face centered cubic (FCC) structure. In a body centered cubic (BCC) structure, 8 organic ammonium (OA) is located at all vertices of the cube. Pb is shown as an example of the central metal at this time.

In addition, the inorganic metal halide perovskite nanocrystals have a face centered cubic structure (FCC) with the central metal in the center, and six inorganic halide materials (X) are located on all surfaces of the cube, and the body-centered cubic structure ( body centered cubic (BCC), in which 8 alkali metals are located at all vertices of the cube. Pb is shown as an example of the central metal at this time.

At this time, all sides of the cube form 90°, and it includes not only a cubic structure with the same horizontal and vertical lengths and heights, but also a tetragonal structure with the same horizontal and vertical lengths but different heights and lengths.

Therefore, in the two-dimensional structure according to the present invention, 6 inorganic halide materials are located on all surfaces of the cube in a face-centered cubic structure, and 8 organic ammoniums are located at all vertices of the cube in a body-centered cubic structure with the central metal in the center. / As an inorganic hybrid perovskite nanocrystal structure, it is defined as a structure in which the horizontal and vertical lengths are the same but the height is 1.5 times longer than the horizontal and vertical lengths.

The perovskite thin film may be a bulk polycrystal thin film or a thin film made of nanocrystalline particles.

Figure 3 is a schematic diagram showing the difference between the perovskite bulk (Bulk) thin film and perovskite nanocrystalline particles according to the present invention.

As shown in FIG. 3(a), in the perovskite bulk thin film, crystallization and thin film coating are simultaneously formed by evaporating the solvent in the spin coating process of the transparent ionic perovskite precursor. Therefore, since the bulk thin film is greatly affected by thermodynamic parameters such as temperature and surface energy during the thin film formation process, it is composed of very non-uniform and large three- or two-dimensional polycrystals of several hundred nm to several mm. A thin film is formed.

However, as shown in FIG. 3(b), the perovkite nanocrystal particles are first crystallized into particles of a nm size region in a colloidal solution, and then stably dispersed in the solution using a ligand. Since the crystallization of the nanocrystal particles in solution has been completed, when forming a thin film through coating, there is no further growth of crystals, and it is not affected by the coating conditions and forms a nanocrystal particle thin film of several nm level that maintains high luminous efficiency. can

Figure 4 is a schematic diagram showing the metal halide perovskite nanocrystal particles according to the present invention.

On the other hand, Figure 4 is shown as an organic / inorganic hybrid perovskite nanocrystal particles, the inorganic metal halide perovskite nanocrystal particles according to an embodiment of the present invention A site is an alkali metal instead of organic ammonium Except that, it is the same as the description of the organic/inorganic hybrid perovskite nanocrystal particles described above. In this case, the alkali metal material may be, for example, A is Na, K, Rb, Cs or Fr.

Therefore, an organic/inorganic hybrid perovskite will be described as an example.

Referring to FIG. 4 , the organic/inorganic hybrid perovskite nanocrystal particles 100 according to the present invention may include a halide perovskite nanocrystal structure 110 that can be dispersed in an organic solvent. At this time, the organic solvent may be a polar solvent or a non-polar solvent.

For example, the polar solvent includes dimethylformamide, gamma butyrolactone, N-methylpyrrolidone or dimethylsulfoxide, and the non-polar solvent may include dichloroethylene, trichloroethylene, chloroform, chlorobenzene, dichlorobenzene, styrene, dimethylformamide, dimethylsulfoxide, xylene, toluene, cyclohexene or isopropyl alcohol.

In addition, the nanocrystal particles 100 at this time may be in the form of a sphere, a cylinder, an elliptical column, or a polygonal column.

In addition, the size of the nanocrystal particles may be 1 nm to 10 μm or less. preferably 1 nm, 3 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 15 nm, 16 nm, 17 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 700 nm, 900 nm, 1 μm, 2 μm , 5 μm or 10 μm. On the other hand, the size of the nanocrystal particles at this time means a size that does not take into account the length of the ligand to be described later, that is, the size of the remaining portion except for the ligand.

For example, when the nanocrystal particles are spherical, the diameter of the nanocrystal particles may be 1 nm to 30 nm.

In addition, the nanocrystal particles preferably have a diameter larger than the exciton bore diameter. Through this, the emission wavelength of the nanocrystalline particles does not depend on the size of the particles, and the emission wavelength can be determined by the composition of the nanocrystalline particles.

In addition, the band gap energy of these nanocrystal particles may be 1 eV to 5 eV.

Therefore, since the energy band gap is determined according to the constituent material or crystal structure of the nanocrystal particle, by controlling the constituent material of the nanocrystal particle, for example, light having a wavelength of 200 nm to 1300 nm can be emitted.

The halide perovskite material may be an organic/inorganic hybrid perovskite or an inorganic perovskite. The perovskite material is ABX ₃ (three-dimensional, 3D), A ₄ BX ₆ (0D, zero-dimensional). ), AB ₂ X ₅ (2D, 2D), A ₂ BX ₄ (2D, 2D), A ₂ BX ₆ (0D, 0D), A ₂ B ⁺ B ³⁺ X ₆ (3D, 3D) , A ₃ B ₂ X ₉ (2D, 2D), A _n+1 B _n X _3n+1 (quasi-2D, quasi-2D), A _n-1 A' ₂ B _n X _3n+1 (quasi- 2D, quasi-two-dimensional) or A _n-1 A"B _n X _3n+1 (Dion-Jacobson(DJ) perovskite) (n is an integer between 1 and 6). In this case, the A is a monovalent cation, an organic ammonium ion, an organic amidinium ion, an organic guanidium ion, an organic phosphonium ion or an alkali metal ion, or a combination or derivative thereof, and A' is an alkali metal, alkali Earth metals, rare earth metals, long-chain organic cations (spacer), R-NH ₃ , or H ₃ NR-NH ₃ (R is a substituted or unsubstituted C ₁ to C ₂₄ an aliphatic hydrocarbon group, or a substituted or unsubstituted C ₅ to C ₂₄ aromatic hydrocarbon group), wherein A" is a divalent organic cation, and B is a metal, a transition metal, a rare earth metal, an alkaline earth metal, Organic, inorganic, ammonium, derivatives thereof, or a combination of two or more thereof, wherein X may be a halogen ion or a combination of different halogen ions.

Specifically, A is an amidinium-based organic material, an organic ammonium material, and an alkali ion, B is a metal material, and X is a halogen element.

More specifically, the amidinium-based (amidinium group) organic material is methylamidinium, formamidinium (formamidinium, NH ₂ CH=NH ⁺ ), acetamidinium (acetamidinium, NH2C(CH)=NH ₂ ⁺ ) or Guamidinium (NHC(NH)=NH ⁺ ), wherein the organic ammonium material is (CH ₃ NH ₃ ) _n , ((C _x H _2x+1 ) _n NH ₃ ) ₂ (CH ₃ NH ₃ ) _n , (RNH ₃ ) ₂ , (C _n H _2n+1 NH ₃ ) ₂ , (CF ₃ NH ₃ ), (CF ₃ NH ₃ ) _n , ((C _x F _2x+1 ) _n NH ₃ ) ₂ (CF ₃ NH ₃ ) _n , ((C _x F _2x+1 ) _n NH ₃ ) ₂ or (C _n F _2n+1 NH ₃ ) ₂ ) may be (n is an integer greater than or equal to 1, and x is greater than or equal to 1) essence).

The divalent organic cation is aminomethylpiperidium ((aminomethyl)piperidinium; 3AMP), 4-(aminomethyl)piperidinium (4-(aminomethyl)piperidinium; 4AMP), 1,4-phenylenedimecanammonium (1 ,4-phenylenedimethanammonium; PDMA) and 1,4-bis(aminomethyl)cyclohexane (1,4-bis(aminomethyl)cyclohexane; BAC).

In addition, B may be a divalent transition metal, rare earth metal, alkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or a combination thereof. In this case, the rare earth metal may be, for example, Ge, Sn, Pb, Eu or Yb. Also, the alkaline earth metal may be, for example, Ca or Sr. In addition, by forming metals such as Ag, Na, In, and Bi together with the above metals, it is possible to form perovskite including double perovskite or more metals having two central metals.

In addition, X may be Cl, Br, I, or a combination thereof.

The size of the perovskite when nanocrystals are formed can be controlled through ligand length, ligand density, and other reaction conditions (temperature, reaction time), for example, can be controlled to 7 nm to 100 nm. More specifically, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm can be controlled.

Meanwhile, a plurality of organic ligands 120 surrounding the surface of the halide perovskite nanocrystal particles 110 may be further included.

The organic ligand may include an alkyl halide or a carboxylic acid.

The alkyl halide may have the structure of alkyl-X. In this case, the halogen element corresponding to X may include Cl, Br, or I. In addition, the alkyl structure at this time includes acyclic alkyl having a structure of C _n H _2n +1, a primary alcohol having a structure such as C _n H _2n+1 OH, and a secondary alcohol. , tertiary alcohol, alkylamine having an alkyl-N structure (ex. Hexadecyl amine, 9-Octadecenylamine 1-Amino-9-octadecene (C ₁₉ H ₃₇ N)), p-substituted aniline (p-substituted aniline), phenyl ammonium, or fluorine ammonium.

The carboxylic acid is 4,4'-azobis(4-cyanopaleric acid) (4,4'-Azobis(4-cyanovaleric acid)), acetic acid, 5-minosalic acid (5-Aminosalicylic acid), Acrylic acid, L-Aspentic acid, 6-Bromohexanoic acid, Promoacetic acid, Di Chloro acetic acid, Ethylenediaminetetraacetic acid, Isobutyric acid, Itaconic acid, Maleic acid, r-maleimido Butyric acid (r-Maleimidobutyric acid), L-Malic acid (L-Malic acid), 4-nitrobenzoic acid (4-Nitrobenzoic acid), 1-Pyrenecarboxylic acid (1-Pyrenecarboxylic acid) or Ole It may contain oleic acid.

In addition, the halide perovskite nanocrystal particles according to the present invention can provide nanocrystal particles having various band gaps according to the substitution of organic elements.

For example, when n=4 in (C _n H _2n+1 NH ₃ ) ₂ PbBr ₄ , it is possible to provide nanocrystalline particles having a band gap of about 3.5 eV. In addition, when n = 5, it is possible to provide the nanocrystal particles having a band gap of about 3.33 eV. In addition, when n = 7, it is possible to provide the nanocrystal particles having a band gap of about 3.34 eV. In addition, when n = 12, it is possible to provide the nanocrystal particles having a band gap of about 3.52 eV.

In addition, the halide perovskite nanocrystal particles according to the present invention can provide nanocrystal particles having various band gaps according to the substitution of the central metal.

For example, CH ₃ NH ₃ PbI ₃ Nanocrystalline particles including an organic/inorganic perovskite nanocrystal structure may have a bandgap energy of about 1.5 eV. In addition, CH ₃ NH ₃ Sn _0.3 Pb _0.7 I The nanocrystal particles including the organic/inorganic perovskite nanocrystal structure may have a bandgap energy of about 1.31 eV. In addition, CH ₃ NH ₃ Sn _0.5 Pb _0.5 I ₃ Nanocrystalline particles including the organic/inorganic perovskite nanocrystal structure may have a bandgap energy of about 1.28 eV. In addition, CH ₃ NH ₃ Sn _0.7 Pb _0.3 I ₃ Nanocrystal particles including the organic/inorganic perovskite nanocrystal structure may have a bandgap energy of about 1.23 eV. In addition, CH ₃ NH ₃ Sn _0.9 Pb _0.1 I ₃ Nanocrystalline particles including the organic/inorganic perovskite nanocrystal structure may have a bandgap energy of about 1.18 eV. In addition, CH ₃ NH ₃ SnI ₃ Nanocrystalline particles including the organic/inorganic perovskite nanocrystal structure may have a band gap energy of about 1.1 eV. In addition, CH ₃ NH ₃ Pb _x Sn _1-x Br ₃ Nanocrystalline particles including an organic/inorganic perovskite nanocrystal structure may have a band gap energy of 1.9 eV to 2.3 eV. In addition, CH ₃ NH ₃ Pb _x Sn _1-x Cl ₃ Nanocrystalline particles including an organic/inorganic perovskite nanocrystal structure may have a band gap energy of 2.7 eV to 3.1 eV.

5 is a schematic diagram showing a method for manufacturing halide perovskite nanocrystal particles according to the present invention.

Referring to FIG. 5( a ), a first solution in which halide perovskite is dissolved in a polar solvent and a second solution in which a surfactant is dissolved in a non-polar solvent are prepared.

In this case, the polar solvent may include dimethylformamide, gamma butyrolactone, N-methylpyrrolidone, or dimethylsulfoxide, but is limited thereto. not.

In addition, the halide perovskite at this time may be a material having a three-dimensional crystal structure, a two-dimensional crystal structure, or a one-dimensional crystal structure or a zero-dimensional crystal structure.

For example, halide perovskite having a three-dimensional crystal structure may have an ABX ₃ structure. In addition, halide perovskite having a two-dimensional crystal structure may have or include a structure of A ₂ BX ₄ , ABX ₄ or A _n-1 Pb _n X _3n+1 (n is an integer between 2 and 6). have. In addition, halide perovskite having a one-dimensional crystal structure may have an A ₃ BX ₅ structure. In addition, the halide perovskite having a zero-dimensional crystal structure may have an A ₄ BX ₆ structure.

On the other hand, such a perovskite can be prepared by combining AX and BX ₂ in a certain ratio. That is, the first solution may be formed by dissolving AX and BX ₂ in a polar solvent at a certain ratio. For example, by dissolving AX and BX ₂ in a polar solvent at a ratio of 2:1, a first solution in which A ₂ BX ₃ halide perovskite is dissolved may be prepared.

In addition, the non-polar solvent at this time may include dichloroethylene, trichloroethylene, chloroform, chlorobenzene, dichlorobenzene, styrene, dimethylformamide, dimethyl sulfoxide, xylene, toluene, cyclohexene or isopropyl alcohol. can, but is not limited to.

The surfactant may also include an alkyl halide or a carboxylic acid. The type of the alkyl halide or carboxylic acid is the same as described above.

Next, the first solution is mixed with the second solution to form nanocrystal particles.

In the step of mixing the first solution with the second solution to form nanocrystal particles, it is preferable to drop the first solution dropwise into the second solution and mix them. In addition, the second solution at this time may be stirred. For example, nanocrystal particles can be synthesized by slowly adding a second solution in which a precursor of halide perovskite is dissolved drop by drop to a second solution in which an alkyl halide surfactant is dissolved while being strongly stirred.

In this case, when the first solution is dropped into the second solution and mixed, halide perovskite is precipitated from the second solution due to the difference in solubility. Then, the halide perovskite precipitated in the second solution is produced with well-dispersed halide perovskite nanocrystals while the alkyl halide surfactant stabilizes the surface. Therefore, halide perovskite nanocrystals and halide perovskite nanocrystals comprising a plurality of alkyl halide organic ligands surrounding the same can be prepared.

On the other hand, the size of these halide perovskite nanocrystal particles can be controlled by controlling the length or shape factor and amount of the alkyl halide surfactant. For example, shape factor control can control size through linear, tapered or inverted triangular surfactants.

In addition, halide perovskite nanocrystalline particles according to an embodiment of the present invention may have a core-shell structure.

Hereinafter, a core-shell structure halide perovskite nanocrystal particles according to an embodiment of the present invention will be described.

6 is a schematic diagram showing a core-shell structure halide perovskite nanocrystal particles according to the present invention and an energy band diagram thereof.

Referring to Figure 6 (a), the core-shell structure halide halide perovskite nanocrystal particles 100' according to the present invention is a core 115 and a shell 130 surrounding the core 115 structure. it can be seen that In this case, a material having a band gap larger than that of the core 115 may be used as the material for the shell 130 .

At this time, referring to FIG. 6(b) , since the energy bandgap of the shell 130 is larger than that of the core 115, the excitons may be more well constrained to the core perovskite.

7 is a schematic diagram illustrating a method for manufacturing halide perovskite nanoparticles having a core-shell structure according to the present invention.

Referring to FIG. 7( a ), a first solution in which the first halide perovskite is dissolved in a polar solvent is added dropwise to a second solution in which an alkyl halide surfactant is dissolved in a non-polar solvent.

Referring to Figure 7 (b), when the first solution is added to the second solution, the first halide perovskite is precipitated from the second solution due to the difference in solubility, and the precipitated first halide perovskite is The first halide perovskite nanocrystal particles 100 including the well-dispersed first halide perovskite nanocrystal core 115 are produced while the alkyl halide surfactant surrounds and stabilizes the surface. At this time, the nanocrystal core 115 is surrounded by the alkyl halide organic ligands 120 .

Referring to FIG. 7C , a shell 130 including a material having a band gap larger than that of the core 115 is formed to surround the core 115 , and thus halide perovskite nanocrystals having a core-shell structure are formed. Particles 100' can be prepared.

The following five methods can be used for methods of forming such a shell.

As a first method, the shell may be formed using the second halide perovskite solution or the inorganic semiconductor material solution. That is, a second halide perovskite having a bandgap larger than that of the first halide perovskite or a third solution in which an inorganic semiconductor material is dissolved is added to the second solution to surround the second halide perovskite core A shell comprising skyte nanocrystals or inorganic semiconductor materials or organic polymers may be formed.

For example, while strongly stirring the halide perovskite (MAPbBr ₃ ) solution generated through the above-described method (Inverse nano-emulsion method), the halide perovskite (MAPbCl ₃ ) solution having a larger band gap than MAPbBr ₃ ) , or a solution of an inorganic semiconductor material such as ZnS or metal oxide, or polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, polyethyleneimine, polyvinyl alcohol An organic polymer such as (PVA) may be slowly dropped dropwise to form a shell including a second halide perovskite nanocrystal (MAPbCl ₃ ) or an inorganic semiconductor material. In this case, MA means methylammonium.

Since core perovskite and shell perovskite mix with each other to form an alloy or adhere to each other, halide perovskite nanocrystals with a core-shell structure can be synthesized.

Accordingly, halide perovskite nanocrystal grains having a MAPbBr ₃ /MAPbCl ₃ core-shell structure may be formed.

As a second method, the shell can be formed using an organoammonium halide solution. That is, a large amount of an organoammonium halide solution is added to the second solution and stirred to form a shell having a larger band gap than the core surrounding the core.

For example, the MACl solution is added to the halide perovskite ( _{MAPbBr 3} ) solution produced by the method as described above (inverse nano-emulsion method) and stirred vigorously _{. x} Cl _x may be converted to form a shell.

Accordingly, halide perovskite nanoparticles having a MAPbBr ₃ /MAPbBr _3-x Cl _x core-shell structure can be formed.

As a third method, a shell can be formed using a pyrolysis/synthesis method. That is, after heat-treating the second solution to thermally decompose the surface of the core, an organoammonium halide solution is added to the heat-treated second solution to synthesize the surface again, so that the band gap is greater than that of the core surrounding the core. Can form large shells.

For example, the halide perovskite (MAPbBr ₃ ) solution generated through the inverse nano-emulsion method as described above is thermally decomposed to change the surface to PbBr ₂ , and then MACl solution is added. Thus, the surface can be synthesized to be MAPbBr ₂ Cl again to form a shell.

Accordingly, halide perovskite nanocrystal grains having a MAPbBr ₃ /MAPbBr ₂ Cl core-shell structure can be formed.

Therefore, the halide halide perovskite nanocrystal particles of the core-shell structure formed according to the present invention form a shell with a material having a larger band gap than the core so that the excitons are better bound to the core, and the perovskite is stable in air. The durability of nanocrystals can be improved by preventing the core perovskite from being exposed to the air by using an inorganic material or an inorganic semiconductor.

As a fourth method, the shell may be formed using an organic semiconductor material solution. That is, an organic semiconductor material having a larger band gap than that of halide perovskite is dissolved in the second solution in advance, and the first solution in which the first halide perovskite is dissolved is added to this second solution. A core comprising halide perovskite nanocrystals and a shell comprising an organic semiconductor material surrounding the core may be formed.

Since the organic semiconductor material adheres to the surface of the core perovskite, halide perovskite with a core-shell structure can be synthesized.

Therefore, MAPbBr ₃ -organic semiconductor core-shell structure halide perovskite nanocrystal particle emitter can be formed.

As a fifth method, a shell may be formed using a selective extraction method. That is, by adding a small amount of IPA solvent to the second solution in which the core containing the first halide perovskite nanocrystal is formed, MABr is selectively extracted from the nanocrystal surface to form the surface only with PbBr ₂ to surround the core. A shell having a larger band gap than the core may be formed.

For example, by adding a small amount of IPA to the halide perovskite (MAPbBr ₃ ) solution generated through the above method (inverse nano-emulsion method), only MABr on the surface of the nanocrystal is selectively dissolved and PbBr on the surface ₂ can be extracted to form a PbBr ₂ shell.

That is, at this time, MABr on the surface of MAPbBr ₃ may be removed through selective extraction.

Therefore, MAPbBr ₃ -PbBr ₂ It is possible to form a halide perovskite nanocrystal particle emitter having a core-shell structure.

8 is a schematic diagram showing halide perovskite nanocrystal particles having a gradient composition structure according to the present invention.

Referring to FIG. 8 , the halide perovskite nanocrystal particle 100 " having a structure having a gradient composition according to an embodiment of the present invention is a halide perovskite nanocrystal structure 140 that can be dispersed in an organic solvent. And, the nanocrystal structure 140 has a gradient composition structure in which the composition changes from the center to the outside, The organic solvent at this time may be a polar solvent or a non-polar solvent.

The halide perovskite at this time has the structure of ABX _3-m X' _m , A ₂ BX _4-l X' _l or ABX _4-k X' _k , wherein A is an amidinium-based organic material or an organic ammonium material, B may be a metallic material, X may be Br, and X' may be Cl. And, the m, l, and k values are characterized in that it increases from the center of the nanocrystal structure 140 toward the outside. The types of A, B and X in the halide perovskite are as described above.

According to the gradient composition, the energy bandgap increases from the center of the nanocrystal structure 140 to the outside.

Meanwhile, the m, l, and k values may gradually increase from the center of the nanocrystal structure toward the outside. Accordingly, the energy bandgap may gradually increase according to the compositional change.

As another example, the m, l, and k values may increase in a step form from the center of the nanocrystal structure toward the outside. Accordingly, the energy bandgap may increase in a step form according to the compositional change.

In addition, a plurality of organic ligands 120 surrounding the halide perovskite nanocrystal structure 140 may be further included. The organic ligand 120 may include an alkyl halide. Usable examples of alkylhalides are as described above.

By making the nanocrystal structure into a gradient-alloy type, it is possible to gradually change the content of perovskite present in a large amount outside the nanocrystal structure and perovskite present in a large amount inside the nanocrystal structure. The gradual content change in the nanocrystal structure uniformly controls the fraction in the nanocrystal structure, reduces surface oxidation, improves exciton confinement in the perovskite present in large amounts, and increases luminous efficiency. It can also increase durability-stability.

The method for manufacturing halide perovskite nanocrystal particles having a gradient composition prepares halide perovskite nanocrystal particles of a core-shell structure, and heat-treats the halide perovskite nanocrystal particles of the core-shell structure to inter-diffusion It can be formed to have a gradient composition through

First, halide perovskite nanocrystal particles having a core-shell structure are prepared. In this regard, the method for manufacturing halide perovskite nanocrystal particles having a core-shell structure is the same as described above with reference to FIG. 7 , and detailed description thereof will be omitted.

Then, the core-shell structured halide perovskite nanocrystal particles may be heat-treated to form a gradient composition through interdiffusion.

For example, halide perovskite having a core-shell structure is annealed at a high temperature to form a solid solution, and then has a gradient composition through interdiffusion by heat treatment.

For example, the heat treatment temperature may be 100 ℃ to 150 ℃. Interdiffusion can be induced by annealing at such an annealing temperature.

In addition, halide perovskite nanocrystal particles having a gradient composition form a first halide perovskite nanocrystal core, and then form a second halide perovskite nanocrystal shell having a gradient composition surrounding the core. can be formed according to

First, a first halide perovskite nanocrystal core is formed. Since this is the same as the method of forming the nanocrystal core described above, a detailed description thereof will be omitted.

Then, a second halide perovskite nanocrystalline shell having a gradient composition surrounding the core is formed.

The second halide perovskite has the structure of ABX _3-m X' _m , A ₂ BX _4-l X' _l or ABX _4-k X' _k , wherein A is an amidinium-based organic material or an organoammonium material; , wherein B may be a metallic material, X may be Br, and X' may be Cl.

Accordingly, a third solution in which the second halide perovskite is dissolved may be added to the second solution while increasing the m, l, or k value.

That is, the ABX _3-m X' _m , A ₂ BX _4-l X' _l or ABX _4-k X' _k solution of which the composition is controlled is continuously dropped to form a shell whose composition is continuously changed. can

9 is a schematic diagram showing a halide perovskite nanocrystal particle having a structure having a gradient composition according to the present invention and an energy band diagram thereof.

Referring to Fig. 9 (a), it can be seen that the nanocrystal particles 100 "according to the present invention have a halide perovskite nanocrystal structure 140 having a gradient composition of varying content. At this time, Fig. 9 (b) Referring to, by changing the composition of the material from the center to the outside of the halide perovskite nanocrystal structure 140, the energy bandgap can be manufactured to increase from the center to the outside.

On the other hand, the perovskite nanocrystal particles according to the present invention may be doped perovskite nanocrystal particles.

The doped perovskite comprises a structure of ABX ₃ , A ₂ BX ₄ , ABX ₄ or A _n-1 B _n X _3n+1 (n is an integer between 2 and 6), wherein a part of A is A ', or a part of B is substituted with B', or a part of X is substituted with X', wherein A and A' are an amidinium-based organic material, an organic ammonium material or an alkali metal material. , wherein B and B' may be a metallic material, and X and X' may be a halogen element.

The kind of the amidinium group organic material and the organic ammonium material is as described above.

In addition, it is preferable that a portion of A is substituted with A', a portion of B is substituted with B', or a ratio of a portion of X substituted with X' is 0.1% to 5%.

10 is a schematic diagram showing doped perovskite nanocrystal particles according to the present invention and an energy band diagram thereof.

10( a ) is a partially cut-away schematic view of the halide perovskite nanocrystal structure 110 doped with the doping element 111 . FIG. 10( b ) is a band diagram of such a doped halide perovskite nanocrystal structure 110 .

Referring to FIGS. 10A and 10B , the semiconductor type may be changed to n-type or p-type by doping halide perovskite. For example, when the halide perovskite nanocrystals of MAPbI ₃ are partially doped with Cl, the electro-optical properties can be adjusted by changing to the n-type. MA at this time is methylammonium.

11 is a cross-sectional view illustrating a method of manufacturing a perovskite light emitting device of the present invention.

Referring to FIG. 11 , an organic solution containing metal halide perovskite nanocrystal particles dispersed in an organic solvent is prepared.

The organic solvent includes a polar solvent or a non-polar solvent, and the polar solvent is dimethylformamide, gamma butyrolactone, N-methylpyrrolidone, or dimethylsulfoxide ( dimethylsulfoxide), and the non-polar solvent is dichloroethylene, trichloroethylene, chloroform, chlorobenzene, dichlorobenzene, styrene, dimethylformamide, dimethylsulfoxide, xylene, toluene, cyclohexene or isopropyl may contain alcohol.

The step of preparing the organic solution includes preparing a first solution in which a metal halide perovskite is dissolved in a polar solvent and a second solution in which a surfactant is dissolved in a non-polar solvent, and adding the first solution to the second solution It may include the step of forming metal halide perovskite nanocrystal particles by mixing. In this regard, since it has already been described above, a detailed description thereof will be omitted.

Then, the organic solution is applied on the first electrode 20 to form the perovskite thin film 30 . The step of forming the perovskite thin film 30 is spin-coating, bar-coating, spray coating, slot-die coating, gravure coating ( gravure coating), blade-coating, screen printing, nozzle printing, inkjet printing, electrohydrodynamic-jet printing, electrospray , characterized in that it is applied by performing electrospinning.

Therefore, when forming a thin film through this printing method, since the perovskite nanocrystal particles form a thin film in a crystallized state, compared to a bulk perovskite thin film in which crystallization is formed during coating, the coating The crystallinity is not affected by the speed, the coating environment and the underlying substrate layer.

Referring to FIG. 24, the bar coating is performed by introducing a solution of perovskite nanocrystals on the first electrode; tilting the first electrode into which the perovskite nanocrystal solution is introduced by giving an inclination angle with respect to the horizontal plane; and performing bar coating on the inclined first electrode and the perovskite nanocrystal particle solution. Introduced the perovskite nanocrystal particle solution onto the substrate or functional film. The introduction of the solution is carried out by drop the solution.

In this case, the step of giving the inclination angle is performed by tilting the introduced substrate or the like at a predetermined angle with respect to a horizontal plane or the ground. The angle of inclination, which is an angle inclined with respect to the horizontal plane, is preferably 30° to 70°. If the inclination angle of the substrate is large, the solution is biased toward the ground due to gravity, so that a thin film having a desired thickness cannot be formed. In addition, if the inclination angle of the substrate is less than 30°, the solvent flow and evaporation effect cannot be sufficiently obtained. Hereinafter, a process of forming a thin film by an inclination angle is performed. In this case, the inclination angle is 30°, 35°, 40°, 41°, 42°, 43°, 44°, 45°, 46°, 47°, 48°, 49°, 50°, 55°, 60°, 65 °, more preferably 70°.

As described above, the perovskite nanocrystal particles (PNC) are aligned by the capillary force acting as an attractive force to each other in the area where the coating has been carried out by giving the inclination angle as described above. In addition, in the area where the bar coating is performed, a certain slope is formed, so that the solvent is rapidly evaporated on the slope surface, the solution is pushed out by the meniscus movement according to gravity, and the perovs according to the convective flow in the lower part of the bar Skye nanocrystals are aligned.

In general, spin coating is generally used to form a perovskite thin film, but bar coating needs to be used to fabricate a large-area device.

However, when a thin film is manufactured using this printing method, the evaporation rate of the solvent is slow, so that large crystals (> μm) may be formed through recrystallization through aggregation of nanocrystal particles.

Therefore, then, the formed nanocrystalline particle thin film is dried. Preferably, it can be dried through air spraying. Therefore, in the present invention, after the organic solution is applied on the substrate, a drying step is further performed to prevent recrystallization between the nanocrystal particles.

For example, it is possible to prevent recrystallization between the nanocrystal particles by directly drying the thin film formed through bar coating or the like through air spraying.

In addition, an organic ligand removal process is added to the perovskite thin film 30 . That is, the organic ligand in the solution that is not bound to the perovskite nanocrystal particles in the applied organic solution is removed.

Next, a passivation layer 40 is formed on the perovskite thin film 30 .

The perovskite thin film 30 shows relatively low luminous efficiency due to the presence of surface defects, and low luminous efficiency by causing charge carrier imbalance in the light emitting device. Accordingly, it is necessary to eliminate the defects of the perovskite thin film 30 and to solve the charge imbalance in the light emitting device.

Accordingly, in the present invention, in the light emitting device including the perovskite thin film 30 as a light emitting layer, a passivation layer 40 is formed on the perovskite thin film 30 .

In the perovskite light emitting device according to the present invention, the passivation layer 40 uses the organic material or compound of the passivation material (1) or (2).

The compound of Formula 1 may stabilize defects in the light emitting layer by supplementing the lack of halogen in the perovskite crystal.

The passivation layer 40 has a thickness of 1 nm to 10 nm, preferably 2 nm to 5 nm. Specifically, it may be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm. If the thickness of the passivation layer exceeds 10 nm, there is a problem in that charge injection is lowered due to insulating properties.

The passivation layer 40 is applied by performing spin coating, bar coating, spray coating, slot die coating, gravure coating, blade coating, screen printing, nozzle printing, inkjet printing, electrohydrodynamic jet printing, electrospray or electrospinning. can be

12 is a schematic diagram for explaining a mechanism in which defects in a perovskite thin film are healed by a passivation layer according to a preferred embodiment of the present invention.

Referring to FIG. 12 , 1,3,5-tris(bromomethyl)-2,4,6-triethylbenzene (TBTB) molecules forming the passivation layer are applied to the defective portion of the perovskite thin film. In order to fill the defects in the crystal structure, Br is debromination from TBTB and replaces the bromine that is desorbed from the perovskite crystal structure. Through this, a passivation operation is performed. Thereafter, a hydrogenation reaction in which hydrogen is bonded to TBTB in which Br is donated to the perovskite thin film proceeds. All of the above reactions are thermodynamically stable reactions, and ΔE has a value less than 0.

A second electrode 50 may be formed on the passivation layer 40 .

The second electrode 50 is a cathode into which electrons are injected, and may be made of a material having a conductive property. When the second electrode 50 is a negative electrode, it is preferably a metal, for example, a metal such as aluminum, magnesium, calcium, sodium, potassium, indium, yttrium, lithium, silver, lead, cesium, or two thereof. It can be formed using a combination of more than one species.

Meanwhile, in one embodiment of the present invention, the first electrode 20 may be used as a cathode, and the second electrode 50 may be used as an anode.

The first electrode 20 or the second electrode 50 may be formed by physical vapor deposition (PVD), chemical vapor deposition (CVD), sputtering, pulsed laser deposition (PLD), evaporation, electron beam evaporation, or atomic layer deposition (ALD). ) and molecular beam epitaxial deposition (MBE).

On the other hand, in the light emitting device according to an embodiment of the present invention, when the first electrode 20 is an anode and the second electrode 50 is a cathode, as shown in FIG. 11 , the first electrode 20 A hole injection layer 23 for facilitating injection of holes or a hole transport layer for transporting holes may be provided between the perovskite thin film (light emitting layer) 30 . In addition, an electron transport layer 43 for transporting electrons and an electron injection layer for facilitating injection of electrons may be provided between the passivation layer 40 and the second electrode 50 .

In addition, a hole blocking layer (not shown) may be disposed between the perovskite thin film (light emitting layer) 30 and the electron transport layer 43 . In addition, an electron blocking layer (not shown) may be disposed between the perovskite thin film (light emitting layer) 30 and the hole transport layer. However, the present invention is not limited thereto, and the electron transport layer 43 may serve as a hole blocking layer, or the hole transport layer may serve as an electron blocking layer.

The hole injection layer 23 and/or the hole transport layer is a layer having a HOMO level between the work function level of the first electrode (anode) 20 and the HOMO level of the perovskite thin film (light emitting layer) 30, The first electrode (anode) 20 functions to increase the injection or transport efficiency of holes from the perovskite thin film (light emitting layer) 30 .

The hole injection layer 23 or the hole transport layer may include a material commonly used as a hole transport material, and one layer may include layers of different hole transport materials. The hole transport material is, for example, mCP (N,Ndicarbazolyl-3,5-benzene), PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrenesulfonate), NPD (N,N′-di(1-naphthyl) -N,N′-diphenylbenzidine), N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diaminobiphenyl (TPD), DNTPD (N ⁴ ,N ^4′ -Bis[4-[bis(3-methylphenyl)amino]phenyl]-N ⁴ ,N ^4′ -diphenyl-[1,1′-biphenyl]-4,4′-diamine), N,N'-diphenyl -N,N'-dinaphthyl-4,4'-diaminobiphenyl, N,N,N'N'-tetra-p-tolyl-4,4'-diaminobiphenyl, N,N,N 'N'-tetraphenyl-4,4'-diaminobiphenyl, or porphyrin compound derivatives such as copper(II)1,10,15,20-tetraphenyl-21H,23H-porphyrin, TAPC (1) ,1-Bis[4-[N,N'-Di(p-tolyl)Amino]Phenyl]Cyclohexane), N,N,N-tri(p-tolyl)amine, 4,4', 4'-tris[ triarylamine derivatives such as N-(3-methylphenyl)-N-phenylamino]triphenylamine, carbazole derivatives such as N-phenylcarbazole or polyvinylcarbazole, phthalocyanine derivatives such as metal-free phthalocyanine or copper phthalocyanine; It may be a starburst amine derivative, an enamine stilbene-based derivative, a derivative of an aromatic tertiary amine and a styryl amine compound, or polysilane. Such a hole transport material may serve as an electron blocking layer.

The hole blocking layer serves to prevent triplet excitons or holes from diffusing in the direction of the second electrode (cathode) 50, and may be arbitrarily selected from known hole blocking materials. For example, an oxadiazole derivative, a triazole derivative, a phenanthroline derivative, or TSPO1 (diphenylphosphine oxide-4-(triphenylsilyl)phenyl) can be used.

The electron injection layer and/or the electron transport layer 43 are layers having a LUMO level between the work function level of the second electrode (cathode) 50 and the LUMO level of the perovskite thin film (light emitting layer) 30, 2 It functions to increase the injection or transport efficiency of electrons from the electrode (cathode) 50 to the perovskite thin film (light emitting layer) 30 .

The electron injection layer may be, for example, LiF, NaCl, CsF, Li ₂ O, BaO, BaF ₂ , or Liq (lithium quinolate).

The electron transport layer 43 is TSPO1 (diphenylphosphine oxide-4-(triphenylsilyl)phenyl), TPBi(1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene), tris(8-quinolinolate) ) aluminum (Alq3), 2,5-diaryl silol derivative (PyPySPyPy), perfluorinated compound (PF-6P), COTs (Octasubstituted cyclooctatetraene), TAZ (refer to the following formula), Bphen (4,7-diphenyl) -1,10-phenanthroline (4,7-diphenyl-1,10-phenanthroline)), BCP (refer to the following formula), or BAlq (refer to the following formula)

.

In the perovskite light emitting device according to the present invention, the passivation layer 40 is formed between the first electrode 20 and the second electrode 50 instead of being inserted between the perovskite thin film 30 and the second electrode 50 in FIG. It may be formed using the organic material or compound of the passivation material (1) or (2) between the perovskite thin films 30, and depending on the perovskite thin film material used, perovskite for more complete passivation It may be simultaneously formed between the skyte thin film 30 and the second electrode 50 and between the first electrode 20 and the perovskite thin film 30 .

Hereinafter, preferred preparation examples and measurement examples are presented to help the understanding of the present invention.

<Preparation Example 1-1> Preparation of halide perovskite nanocrystal particles

Halide perovskite nanoparticles having a three-dimensional structure were formed through the ligand-assisted recrystallization (LARP) method. Specifically, a first solution was prepared by dissolving halide perovskite in a polar solvent. In this case, dimethylformamide was used as a polar solvent, and FAGAPbBr ₃ (FA is formamidinium, GA is guanidium) was used as a halide perovskite. In this case, the FAGAPbBr ₃ used was a mixture of FABr, GABr, and PbBr ₂ in a molar ratio of 9:1:5.

Then, a second solution in which an alkyl halide surfactant was dissolved in a non-polar solvent was prepared. In this case, toluene was used as the non-polar solvent, and decylamine (C ₁₀ H ₂₃ N) and oleic acid (oleic acid, C ₁₈ H ₃₄ O ₂ ) were used as the surfactant.

Then, 150 μl of the first solution was injected into the second solution while being strongly stirred to form halide perovskite nanoparticles having a three-dimensional structure.

Then, the halide perovskite nanocrystal particles in the solution state were coated on a glass substrate to form a halide perovskite nanocrystal particle thin film. The size of the formed halide perovskite nanocrystal particles at this time is about 10 nm.

In particular, in the halide perovskite nanocrystal grains, the compositional formula of the crystal grains excluding the surfactant acting as an organic ligand is FA _0.9 GA _0.1 PbBr ₃ .

<Preparation Example 1-2> Preparation of a perovskite light emitting device including a passivation layer

After preparing an ITO substrate (a glass substrate coated with ITO anode), PEDOT:PSS (AI4083 from Heraeus) and perfluoride ionomer (PFI, Nafion resin 5wt% from Sigma-aldrich) were added on the ITO anode to 1 After spin-coating the mixed solution in a weight ratio of :1.5, heat treatment was performed at 150° C. for 30 minutes to form a hole injection layer with a thickness of 50 nm.

150 μl of the solution in which the halide perovskite nanocrystal grains according to Preparation Example 1-1 are dissolved on the hole injection layer was dropped onto the PEDOT:PSS/PFI thin film, and after a holding time for 10 minutes , spin-coated and heat-treated at 90° C. for 10 minutes to form a halide perovskite nanocrystal particle emission layer.

Next, 1,3,5-tris(bromomethyl)-2,4,6-triethylbenzene (TBTB) of the following Chemical Formula 5-1 was dissolved in a non-polar solvent to prepare a solution for a passivation layer. At this time, toluene was used as the non-polar solvent, and the solution was prepared at a concentration of 1 mg/mL.

[Formula 5-1]

Next, the solution for the passivation layer was spin-coated on the light emitting layer having halide perovskite nanocrystal particles, and heat treatment was performed at 90° C. for 10 minutes to form a passivation layer having a thickness of 5 nm.

Thereafter, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) having a thickness of 50 nm was deposited on the TBTB passivation layer at a high vacuum of 1×10 ^-7 Torr or less. A halide perovskite light emitting device was manufactured by forming an electron transport layer, depositing 1 nm thick LiF thereon to form an electron injection layer, and depositing 100 nm thick aluminum thereon to form a negative electrode.

In addition, a person skilled in the art may use an appropriate material as the passivation layer in consideration of the composition of the light emitting layer. That is, F, Cl or I can be selectively applied by substituting Br in TBTB to suit the emitted color and perovskite composition. That is, the passivation layer that can be used in this preparation is according to Chemical Formula 5 below.

[Formula 5]

In Formula 5, X ₁ , X ₂ or X ₃ is F, Cl, Br, or I.

<Preparation Example 1-3> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-1 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-1]

In Formula 1-1, R ₁ , R ₃ and R ₅ are C ₂ H ₅ , and R ₂ , R ₄ and R ₆ are CH ₂ Br.

<Preparation Example 1-4> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-2 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-2]

In Formula 1-2, R ₁ , R ₃ and R ₅ are C ₃ H ₇ , and R ₂ , R ₄ and R ₆ are CH ₂ Br.

<Preparation Example 1-5> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-3 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-3]

In Formula 1-3, R ₁ , R ₃ and R ₅ are C ₄ H ₉ , and R ₂ , R ₄ and R ₆ are CH ₂ Br.

<Preparation Example 1-6> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was prepared in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-4 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-4]

In Formula 1-4, R ₁ , R ₃ and R ₅ are a phenyl group, and R ₂ , R ₄ and R ₆ are CH ₂ Br.

<Preparation Example 1-7> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-5 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-5]

In Formula 1-5, R ₁ , R ₃ and R ₅ are -C=C, that is, (C ₂ H ₃ ), and R ₂ , R ₄ and R ₆ are CH ₂ Br.

<Preparation Example 1-8> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-6 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-6]

In Formula 1-6, R ₁ , R ₃ and R ₅ are *-C=CC, that is, C ₃ H ₅ , and R ₂ , R ₄ and R ₆ are CH ₂ Br.

<Preparation Example 1-9> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-7 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-7]

In Formula 1-7, R ₁ , R ₃ and R ₅ are CH ₃ , and R ₂ , R ₄ and R ₆ are Br.

<Preparation Example 1-10> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-8 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-8]

In Formula 1-8, R ₁ , R ₃ and R ₅ are CH ₃ , and R ₂ , R ₄ and R ₆ are C ₂ H ₄ Br.

<Preparation Example 1-11> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was prepared in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-9 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-9]

In Formula 1-9, R ₁ , R ₃ and R ₅ are CH ₃ , and R ₂ , R ₄ and R ₆ are C ₃ H ₆ Br.

<Preparation Example 2-1> Preparation of a perovskite light emitting device including a passivation layer

After preparing an ITO substrate (a glass substrate coated with an ITO anode), spin-coating a solution of a conductive material PEDOT:PSS (AI4083 from Heraeus) and PFI in a 1:1.5 weight ratio on the ITO anode was spin-coated, and then at 150°C. A hole injection layer with a thickness of 50 nm was formed by heat treatment for 30 minutes.

A solution in which halide perovskite nanocrystal particles according to Preparation Example 1-1 are dissolved on the hole injection layer. After 150 μl was added dropwise and dried for 10 minutes, spin-coated and heat-treated at 90° C. for 10 minutes to form a halide perovskite nanocrystal particle emission layer.

Next, a solution for a passivation layer was spin-coated on the light emitting layer having halide perovskite nanocrystal particles, and heat treatment was performed at 90° C. for 10 minutes to form a passivation layer.

The solution for the passivation layer was prepared by mixing a compound containing a halogen group and an organic material in a non-polar solvent in a molar ratio of 1:1. In this case, the nonpolar solvent is toluene, and the compound containing the halogen group is 1,3,5-tris(bromomethyl)-2,4,6-triethyl which is a compound represented by the following Chemical Formula 5-1 benzene (TBTB), and the organic material is ,3,5-tris(N-phenylbenzimidazol-2-yl)benzene {1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene, TPBI} .

[Formula 5-1]

[Formula 6]

In this case, Chemical Formula 6 is the structural formula of TPBI.

Thereafter, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) having a thickness of 50 nm was deposited on the TBTB passivation layer at a high vacuum of 1×10 ^-7 Torr or less. A halide perovskite light emitting device was manufactured by forming an electron transport layer, depositing 1 nm thick LiF thereon to form an electron injection layer, and depositing 100 nm thick aluminum thereon to form a negative electrode.

In addition, those skilled in the art may use an appropriate material as the passivation layer in consideration of the composition of the light emitting layer. That is, F, Cl, or I can be selectively applied by substituting Br in TBTB to suit the emitted color and perovskite composition. That is, the passivation layer that can be used in this preparation is according to Chemical Formula 5 below.

[Formula 5]

In Formula 5, X ₁ , X ₂ or X ₃ is F, Cl, Br, or I.

<Preparation Example 2-2> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 2-1, but TBMM was used as a compound containing a halogen group in the solution for the passivation layer.

<Preparation Example 2-3> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 2-1, but polyethylene oxide (PEO), a polymer, was used instead of TPBI as an organic material for the passivation layer solution.

<Preparation Example 2-4> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 2-1, but the molar ratio of the compound and organic material containing the halogen group in the solution for the passivation layer was 1:0.2.

<Preparation Example 2-5> Preparation of a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 2-1, but the molar ratio of the compound and organic material containing a halogen group in the solution for the passivation layer was 1:12.

<Comparative Preparation Example 1-1> Preparation of a perovskite light emitting device excluding passivation layer

After preparing an ITO substrate (a glass substrate coated with an ITO anode), spin coating a solution of a conductive material PEDOT:PSS (AI4083 from Heraeus) and PFI in a 1:1.5 weight ratio on the ITO anode was spin-coated at 150°C. A hole injection layer having a thickness of 50 nm was formed by heat treatment for 30 minutes. 150 μl of the solution in which the halide perovskite nanocrystal particles according to Preparation Example 1 are dissolved according to Preparation Example 1 was added dropwise to 150 μl on the hole injection layer, dried for 10 minutes, and then the remaining solution in an undried state was spin (spin) ) and heat-treated at 90° C. for 10 minutes to form an organic/inorganic hybrid perovskite nanocrystal particle emission layer.

After that, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) having a thickness of 50 nm was deposited on the light emitting layer at a high vacuum of 1×10 ^-7 Torr or less to form an electron transport layer A halide perovskite light emitting device was manufactured by forming a negative electrode by depositing a 1 nm thick LiF thereon to form an electron injection layer, and depositing 100 nm thick aluminum thereon to form a negative electrode.

<Comparative Preparation Example 1-2> Preparation of a perovskite light emitting device comprising another passivation layer 1

It was prepared in the same manner as in Preparation Example 1-2, but the following compound 2,4,6-tris(bromomethyl)mesitylene (TBMM) was used as a passivation layer.

<Comparative Preparation Example 1-3> Preparation of a perovskite light emitting device including another passivation layer 2

It was prepared in the same manner as in Preparation Example 1-2, but the following compound 1,3,5-tris(bromomethyl)benzene (TBB) was used as a passivation layer.

<Comparative Preparation Example 1-4> Preparation of a perovskite light emitting device comprising another passivation layer 3

It was prepared in the same manner as in Preparation Example 1-2, but the following compound 1,2,4,5-tetrakis(bromomethyl)benzene (TKBB) was used as a passivation layer.

<Comparative Preparation Example 1-5> Preparation of a perovskite light emitting device including another passivation layer 4

It was prepared in the same manner as in Preparation Example 1-2, but the following compound hexakis(bromomethyl)benzene (HBB) was used as a passivation layer.

<Comparative Preparation Example 1-6> Preparation of a perovskite light emitting device including another passivation layer 5

It was prepared in the same manner as in Preparation Example 2, but the following compound poly(pentabromophenyl methacrylate) was used as a passivation layer.

<Comparative Preparation Example 1-7> Preparation of a perovskite light emitting device including another passivation layer 6

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-10 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-10]

In Formula 1-10, R ₁ , R ₃ and R ₅ are an alkyl group having 7 carbon atoms, and R ₂ , R ₄ and R ₆ are CH ₂ Br.

<Comparative Preparation Example 1-8> Preparation of a perovskite light emitting device including another passivation layer 7

A perovskite light emitting device was manufactured in the same manner as in Preparation Example 1-2, but a compound represented by the following Chemical Formula 1-12 was used instead of the compound of Chemical Formula 5-1.

[Formula 1-12]

In Formula 1-12, R ₁ , R ₃ and R ₅ are CH ₃ , and R ₂ , R ₄ and R ₆ are C ₅ H ₁₀ Br.

<Experimental Example> Measurement of perovskite light emitting device characteristics

The perovskite light emitting devices prepared in Preparation Examples 1-2 to Preparation 1-11, Comparative Preparation Examples 1-1 to Comparative Preparation Examples 1-8, Preparation Examples 2-1 to Preparation Examples 2-5 were prepared as follows. The properties were measured by the method, and the results are shown in Tables 1 to 5 below.

(1) External quantum efficiency (EQE) measurement

By connecting an electrode to the light emitting device and increasing the voltage at regular intervals in a constant voltage mode, the light generated from the device is analyzed through the Spectroradiometer (cs-2000) equipment, and the electricity according to the angle is analyzed. The external quantum efficiency (%) was measured by measuring an angle-dependent electroluminescence intensity profile.

(2) Measurement of current density

By connecting an electrode to the light emitting device and increasing the voltage at regular intervals in a constant voltage mode, the current flowing through the source measure unit (keithley 2400) is measured through a source measure unit (keithley 2400) and divided by the size of the light emitting area to emit light. The current density of the device was measured.

production example
1-2 production example
1-3 production example
1-4 production example
1-5 production example
1-6 matter (One) TBTB Formula 1-1 Formula 1-2 Formula 1-3 Formula 1-4 (2) - - - - - External luminous efficiency (%) 25.56 24.12 23.58 22.94 23.21 Current density (mA/cm ² ) 66.65 64.14 63.47 61.54 63.11

production example
1-7 production example
1-8 production example
1-9 production example
1-10 production example
1-11 matter (One) Formula 1-5 Formula 1-6 Formula 1-7 Formula 1-8 Formula 1-9 (2) - - - - - External luminous efficiency (%) 23.14 23.38 23.74 23.44 22.89 Current density (mA/cm ² ) 67.15 68.33 65.73 64.45 63.17

Comparative Preparation Example
1-1 Comparative Preparation Example
1-2 Comparative Preparation Example
1-3 Comparative Preparation Example
1-4 matter (One) x TBMM TBB TKBB (2) - - - - External luminous efficiency (%) 21.65 22.56 20.23 19.84 Current density (mA/cm ² ) 71.24 58.84 54.29 53.67

Comparative Preparation Example
1-5 Comparative Preparation Example
1-6 Comparative Preparation Example
1-7 Comparative Preparation Example
1-8 matter (One) HBB poly(pentabromophenyl methacrylate) Formula 1-10 Formula 1-11 (2) - - - - External luminous efficiency (%) 19.22 18.21 20.47 20.11 Current density (mA/cm ² ) 53.11 37.21 45.13 47.66

production example
2-1 production example
2-2 production example
2-3 production example
2-4 production example
2-5 matter type TBTB+TPBI TBMM+TPBI TBTB+PEO TBTB+TPBI TBTB+TPBI molar ratio 1:1 1:1 1:1 1:0.2 1:12 External luminous efficiency (%) 26.12 23.27 26.03 2.86 21.56 Current density (mA/cm ² ) 70.23 60.82 62.65 68.21 72.35

Looking at Tables 1 to 5, the perovskite light emitting devices prepared in Preparation Examples 1-2 to 1-11 have light emitting device external quantum efficiency and higher than Comparative Preparation Examples 1-1 to 1-8. It was confirmed that the current density was excellent.

More specifically, in Comparative Preparation Example 1-2 (TBMM) and Comparative Preparation Example 1-3 (TBB), it was confirmed that the current density was decreased compared to TBTB, which was found that the halide of the molecule was on the substituted carbon and adjacent carbon. As the length of the substituted substituents becomes shorter, the arrangement of passivation molecules in the thin film becomes non-uniform, which prevents the injection of electrons into the perovskite crystal compared to repairing the perovskite surface defects and causes the device to emit light This is expected to be due to the reduced efficiency.

Preparation Examples 1-3 to Preparation Examples 1-5 have higher current density and external quantum efficiency of the device than Comparative Preparation Examples, but compared to Preparation Example 1-2 (TBTB), the halide-substituted carbon and adjacent carbon As the length of the substituted substituent increases, it can be seen that the current density is gradually decreased and the external quantum efficiency of the light emitting device is also gradually decreased. Furthermore, as in Comparative Preparation Example 1-7, when the length of carbon is increased by more than a certain amount, it can be confirmed that the arrangement of passivation molecules in the thin film becomes non-uniform, so that the current density and device efficiency decrease sharply.

In Preparation Example 1-6, the current density and external quantum efficiency of the device were higher than those of Comparative Preparations, but the volume of the substituent substituted on the halide-substituted carbon and the adjacent carbon was larger than that of Preparation Example 1-2 (TBTB). It can be seen that the arrangement of the passivation molecules in the thin film is relatively non-uniform, so that the current density gradually decreases and the external quantum efficiency of the light emitting device also decreases.

Preparation Examples 1-7 to Preparation Examples 1-8 are unsaturated compounds containing unsaturated bonds such as double bonds and triple bonds, and have higher current density and external quantum efficiency of the device compared to Comparative Preparation Examples, especially due to the presence of unsaturated bonds It can be seen that the current density is greatly improved.

Preparation Examples 1-9 to Preparation Examples 1-11 are compounds having different lengths of substituents including silver halide, and it can be confirmed that they have higher current density and external quantum efficiency of the device compared to Comparative Preparation Examples. However, as in Comparative Preparation Example 1-8, when the length of the substituent is longer than a certain length, the arrangement of the passivation molecules in the thin film becomes non-uniform, and it can be seen that the current density and device efficiency are sharply decreased.

On the other hand, looking at Table 5, it can be seen that Preparation Example 2-1, in which a mixture of a compound and an organic material is applied to the passivation layer, has excellent current density and external quantum efficiency of the device, which means that the passivation material is a defect of the perovskite. It is believed that this is because TPBI, an electron injection layer material, improves the luminous efficiency and current density by promoting electron injection into the perovskite layer.

In addition, in Preparation Example 2-3 using a polymer as an organic material, compared with Preparation Example 1-2 using only TBTB, it can be seen that the current density is decreased but the external quantum efficiency is increased, which is that the polymer layer interferes with electron injection, but It was predicted that this is because it has the effect of healing perovskite defects together with TBTB.

In addition, Preparation Examples 2-4 to Preparation 2-5, in which the molar ratio of the compound having a halogen group and the organic material are out of 1: 0.7 to 1.4, showed somewhat poor performance compared to Preparation Example 2-1, which was mixed at 1:1. visibility could be confirmed.

Specifically, in Preparation Example 2-4, wherein the molar ratio is less than 1: 0.7, it can be seen that the current density is slightly increased, but the external quantum efficiency of the light emitting device is decreased. Accordingly, it is considered that the effect of promoting electron injection was insignificant, but had an adverse effect that prevented the uniform application of TBTB.

In addition, in Preparation Example 2-5, in which the molar ratio exceeds 1:1.4, it was confirmed that the current density was greatly improved but the external quantum efficiency of the light emitting device was decreased, which helps the injection of the TPBI valence electron transport layer material, but relatively It is predicted that this is because the large TPBI molecule interferes with the uniform application of TBTB, which prevents sufficient perovskite defect healing, thereby reducing the luminous efficiency of the device.

<Measurement Example 1> Measurement of external quantum efficiency-voltage characteristics according to whether or not a passivation layer is formed on the perovskite thin film

External quantum efficiency-voltage characteristics of the light emitting device manufactured in Preparation Example 1-2 and the light emitting device manufactured by Comparative Preparation Example 1-1 were measured.

13 is a graph showing the external quantum efficiency according to Measurement Example 1 of the present invention.

13, the light emitting device of Preparation Example 1-2 in which a passivation layer using TBTB is formed on the light emitting layer has high external quantum efficiency compared to the light emitting device of Comparative Preparation Example 1-1 of the same structure in which the passivation layer is not formed. indicates. That is, when the passivation layer using TBTB is formed, the maximum value of the external quantum efficiency EQE is 25.56%, whereas when the passivation layer is not intervened, the maximum value of the external quantum efficiency EQE remains at 21.65%. That is, it is confirmed that the external quantum efficiency is increased by 1.18 times by the introduction of the passivation layer of the present invention.

From this, it can be seen that the passivation layer using the TBTB can be usefully used as a passivation layer by stabilizing the defects of the perovskite light emitting layer.

<Measurement Example 2> Measurement of capacitance-temperature characteristics according to whether or not a passivation layer is formed on a perovskite thin film

The following experiment was performed to investigate the change in defect density of the light emitting device according to the presence or absence of the formation of a passivation layer including TBTB on the perovskite light emitting layer.

Specifically, capacitance-temperature characteristics of the light emitting device manufactured in Preparation Example 2 and the light emitting device of Comparative Preparation Example 1-1 were measured.

14 is a graph illustrating capacitance-temperature characteristics of light emitting devices according to Measurement Example 2 of the present invention.

Referring to FIG. 14 , in the light emitting device of Preparation Example 1-2, the capacitance peak was decreased. This indicates that the passivation layer using TBTB stabilizes the defects of the perovskite light emitting layer. That is, as the number of defects in the light emitting layer decreases, the intensity of the peak of the capacitance graph decreases, and it is confirmed that the intensity of the peak in the 200K to 300K region is reduced. This is confirmed through Table 6 below.

Fault activation energy (eV) Defect concentration (N _t (cm ^-3 )) FAPbBr ₃

0.5

0.5 4.93×10 ¹² Preparation Example 1-2

0.5 3.10×10 ¹² Preparation 1-1

0.5 1.70×10 ¹²

In Table 6, the defect concentration of the light emitting layer is calculated through deep-level transient sectroscopy. As shown in Table 1, it is confirmed that the defect density of the light emitting layer is reduced by the passivation layer using TBTB.

<Measurement Example 3> Measurement of external quantum efficiency/electrical efficiency-voltage characteristics according to whether or not a passivation layer is formed on the perovskite thin film

External quantum efficiency-voltage characteristics and electrical efficiency-voltage characteristics were measured for the light emitting devices manufactured in Preparation Example 1-2 and the light emitting devices of Comparative Preparation Examples 1-2 and 1-3.

15 is a graph illustrating an external quantum efficiency-voltage characteristic and an electrical efficiency-voltage characteristic according to Measurement Example 3 of the present invention.

15A shows an external quantum efficiency-voltage characteristic. When the passivation layer using TBTB is formed on the light emitting layer, it can be seen that the external quantum efficiency is higher than that of a light emitting device using other types of passivation layers.

15B also shows the electrical efficiency-voltage characteristic. When the passivation layer using TBTB is formed on the light emitting layer, it can be seen that it has high electrical efficiency compared to the light emitting device using other types of passivation layers.

15A and 15B, the light emitting device to which the TBTB passivation layer is applied exhibits a maximum external quantum efficiency of 25.56% and a maximum current efficiency of 110.23 cd/A, whereas the TBMM is passivated. The light emitting device of Comparative Preparation Example 1-2 used as a layer exhibits an external quantum efficiency of up to 22.56% and an electrical efficiency of up to 96.95 cd/A. In addition, the light emitting device of Comparative Preparation Examples 1-3 using TBB as a passivation layer exhibits an external quantum efficiency of up to 20.23% and an electrical efficiency of up to 86.3 cd/A.

That is, the increase in external quantum efficiency and electrical efficiency in the same structure is due to the reduction of defects in the light emitting layer and the securing of structural stability. That is, the change in properties in the light emitting layer having the same thickness and the same material is directly related to the reduction of defects in the light emitting layer.

<Measurement Example 4> Measurement of properties according to the waiting time of a solution when forming a perovskite thin film

For the formation of the perovskite light emitting layer in Preparation Example 1-2, a solution in which perovskite nanocrystal particles are dissolved is added dropwise, and the drying process is started by giving a holding time for 10 minutes.

However, the holding time of 10 minutes provided in Preparation Example 1-2 corresponds to one manufacturing example, and it is preferable that a holding time of 1 minute to 50 minutes is provided. Specifically, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 20 minutes, It can be 30 minutes, 40 minutes, 50 minutes. The thickness of the thin film varies depending on the holding time, and the conditions vary depending on the temperature and humidity of the glove box and the atmosphere when the thin film is formed. By providing the holding time, the perovskite thin film acting as the light emitting layer becomes more dense and high optical properties can be obtained. However, if the holding time is less than 1 minute, the alignment of the lower nanocrystal particles or fixing on the lower film quality is not smooth, so that a dense thin film cannot be obtained. In addition, if the holding time exceeds 50 minutes, the process time is long and it is difficult to obtain uniformity of the thin film by spin coating according to evaporation of the solvent. Preferably, a time of 2 minutes or more and 15 minutes or less may be used in a conventional process. If the holding time is left longer, the ligand will float further upward, so that defects on the surface can be more controlled. In addition, since the ligand can act as an insulator, a process of removing only the ligand on top of this additional ligand by spin-coating only a solvent can be additionally used. This process is called the Ligand Removal Process.

In this preparation example, the holding time is given for 10 minutes. Even if a holding time of 10 minutes is given, not all of the sprayed and dripped solution is dried, and the undried solution is coated through spinning.

16 is a schematic diagram of forming a perovskite light emitting layer by giving a holding time according to Measurement Example 4 of the present invention.

Referring to FIG. 16 , a solution in which perovskite nanocrystal particles are dissolved is dropped onto a substrate or other functional film.

In addition, when the dropped solution is in a solution state on the lower substrate (electrode or hole injection layer), spin coating is not performed immediately, and a holding time is given. When the holding time is given, the solvent partially evaporates, and the perovskite nanocrystal particles are immobilized on the surface in contact with the substrate or other film quality. Thereafter, when spin coating is performed on the solution remaining thereon, a light emitting layer having a uniform thickness may be formed.

17 is an SEM image of the perovskite light emitting layer according to the holding time according to Measurement Example 4 of the present invention.

Referring to FIG. 17A , aggregation phenomenon due to attraction between particles occurs in the film quality immediately spin-coated without being given a waiting time after introduction of the solution. That is, it is confirmed that a dense and uniform film quality cannot be obtained. On the other hand, referring to FIG. 17B , it was found that the density of the thin film was increased in the perovskite light emitting layer having a holding time of a predetermined time or longer compared to the light emitting layer having no holding time as shown in FIG. 17A .

From this, it is confirmed that the holding time before coating can be usefully used as a method to increase the luminous efficiency by improving the density of the perovskite thin film, and to form a high-performance light emitting layer.

18 is a graph showing the light emission and absorbance of the perovskite light emitting layer according to the holding time according to Measurement Example 4 of the present invention.

Referring to FIG. 18 , it was found that the perovskite light emitting layer having a holding time of a predetermined time or longer had higher light emission and absorbance of the thin film compared to the light emitting layer having no holding time. That is, there is a large difference in photoluminescence characteristics and absorbance of the light emitting device of Preparation Example 1-2 to which a holding time is not provided and the light emitting device of Preparation Example 1-2 to which a holding time of 10 minutes is provided. The peak of photoluminescence (indicated by PL) appears at 534 nm as well. However, it is confirmed that the strength is 22.33 a.u. in the sample with a holding time of 10 minutes, which is approximately 11.5 times higher than that of 1.95 a.u. in the case of not. In addition, it is confirmed that the absorbance intensity is increased by about 1.5 times from 0.123 a.u. to 0.179 a.u. at 400 nm.

From this, it was confirmed that the holding time before coating can be usefully used as a method for forming a high-performance light emitting layer by improving the density of the perovskite thin film and improving optical properties.

19 is a graph measuring the electrical efficiency of the perovskite light emitting layer according to the holding time according to Measurement Example 4 of the present invention.

Referring to FIG. 19A , it was found that the perovskite thin film having a holding time of more than a certain time increased the electrical efficiency of the device compared to the thin film having no holding time. That is, when the holding time of 10 minutes is applied, the maximum electric efficiency is 49.6 cd/A, which is very high compared to the maximum electric efficiency of 37.4 cd/A in the case where it is not.

In addition, referring to FIG. 19B , as disclosed in Preparation Example 1-2, the electrical efficiencies of a plurality of samples to which a holding time is not provided and a plurality of samples to which a holding time of 10 minutes are applied are compared. The increase in electrical efficiency is confirmed for the sample to which the holding time is given compared to the sample to which it is not.

From this, it was confirmed that the holding time before spin coating can be usefully used as a method for forming a high-performance light emitting layer by improving the density of the perovskite thin film and blocking the leakage path of charge carriers.

<Preparation Example 3> Using an organic ligand removal process, manufacturing a perovskite light emitting device including a passivation layer

A perovskite light emitting device was manufactured in the same process as in Preparation Example 1-2. However, when the perovskite light emitting layer is formed, a holding time of 10 minutes is given and spin coating is performed, and then 0.7 ml of toluene is sprayed and spin coated on the thin foil on which spin coating has been performed. Thereafter, heat treatment is performed at 90° C. in the same manner as in Preparation Example 1-2 to form a perovskite light emitting layer.

20 is a schematic diagram for explaining the ligand removal process according to Preparation Example 3 of the present invention.

In the perovskite nanocrystal particle solution, the organic ligand resulting from the surfactant is distributed in the solution. The organic ligand binds to the surface of the nanocrystal grains and prevents aggregation between the grains. However, organic ligands that are not bound to the surface of the nanocrystal particles are suspended in the solution. It is removed via toluene.

<Measurement Example 5> Measurement of characteristics of perovskite light emitting device according to the presence or absence of organic ligand removal process

In this measurement example, the light emitting device of Preparation Example 1-2 and the light emitting device of Preparation Example 3 are compared.

21 is a graph showing FTIR data of a perovskite light emitting layer in light emitting devices according to Measurement Example 5 of the present invention.

Referring to FIG. 21 , it is confirmed that the peak corresponding to oleic acid corresponding to the organic ligand is greatly reduced in the sample of Preparation Example 3 to which the organic ligand removal process is applied. Through this, it can be confirmed that not only the thickness of the thin film is reduced, but also the side effects caused by the excess organic ligand are eliminated, the charge injection operation becomes smooth, and the efficiency is improved.

22 is a graph illustrating current densities of light emitting devices according to Measurement Example 5 of the present invention.

Referring to FIG. 22 , it is confirmed that the light emitting device of Preparation Example 3 has a higher current density than the light emitting device of Preparation Example 1-2. It is confirmed that a kind of insulating effect or an obstruction of charge transfer is resolved by the organic ligand floating in the solution, and the performance of the light emitting device is improved.

23 is a graph illustrating electrical efficiency and luminance of light emitting devices according to Measurement Example 5 of the present invention.

Referring to FIG. 23 , the light emitting device of Preparation Example 3 exhibits an electrical efficiency of up to 75.1 cd/A, and the light emitting device of Preparation Example 1-2 exhibits an electrical efficiency of up to 49.6 cd/A. In addition, the light emitting device of Preparation Example 3 exhibits a maximum luminance of 18,709 cd/m 2 , and the light emitting device of Preparation Example 1-2 exhibits a maximum luminance of 971 cd/m 2 . That is, it can be seen that the light emitting device on which the organic ligand removal process is performed is not combined with the perovskite, and the free ligand remaining in the thin film is sufficiently removed, thereby exhibiting high electrical efficiency and luminance characteristics.

<Preparation Example 4> Preparation of a perovskite light emitting device comprising a passivation layer using a bar coating

After preparing an ITO substrate (a glass substrate coated with ITO anode), PEDOT:PSS (AI4083 from Heraeus) and perfluorinated ionomer (Sigma-Aldrich Nafion ^TM 2wt% in water/ After spin-coating a solution mixed with alcohol solution) (PFI) in a weight ratio of 1:1.5, heat treatment was performed at 150° C. for 30 minutes to form a hole injection layer with a thickness of 50 nm.

Bar coating is performed immediately after 150 μl of the solution in which the halide perovskite nanocrystal particles are dissolved according to Preparation Example 1-1 is added dropwise onto the hole injection layer. In bar-coating, the substrate is tilted at 50° to remove the solvent and at the same time to align the nanocrystal particles. Thereafter, heat treatment was performed at 90° C. for 10 minutes to form a halide perovskite nanocrystal particle emission layer.

Next, a solution in which 1,3,5-tris(bromomethyl)-2,4,6-triethylbenzene (TBTB) is dissolved on the halide perovskite nanocrystal particle emission layer is spin coated and A passivation layer was formed by heat treatment at 90° C. for 10 minutes.

Thereafter, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) having a thickness of 50 nm was deposited on the passivation layer in a high vacuum of 1×10 ^-7 Torr or less, A halide perovskite light emitting device was manufactured by forming an electron transport layer, depositing 1 nm thick LiF thereon to form an electron injection layer, and depositing 100 nm thick aluminum thereon to form a negative electrode.

24 is a schematic diagram for explaining a bar coating applied to form a perovskite light emitting layer according to Preparation Example 4 of the present invention.

<Measurement Example 6> Measurement of properties of perovskite thin films produced through bar coating

During the bar coating disclosed in Preparation Example 4, the change in characteristics according to the inclination of the substrate with respect to the horizontal plane and the characteristics of the light emitting device according to the presence or absence of the bar coating were measured.

25 is a graph and an image of measuring photoluminescence distribution according to Measurement Example 6 of the present invention.

Referring to FIG. 25 , photoluminescence properties at nine points (a to I) were measured during bar coating. In addition, during bar coating, the inclination angle of the substrate is changed from 0° to 70°, and compared with the measured value during spin coating. Spin coating is advantageous for forming a light emitting layer with a small area, but bar coating is essential for forming a light emitting layer with a large area. In FIG. 26 , when the substrate has an inclination angle of 30° to 70° with respect to the horizontal plane, a distribution similar to spin coating is shown. In addition, when the inclination angle is 50° to 70°, it is confirmed that photoluminescence properties almost identical to those of spin coating are exhibited.

This shows that when a specific inclination angle is given in bar coating, the same characteristics as spin coating advantageous for coating a small area can be obtained, and a thin film of uniform thickness can be obtained even when bar coating is used in the process of forming a light emitting layer of a large area. Able to know.

26 is a SEM image showing the surface uniformity of the light emitting layer according to Measurement Example 6 of the present invention.

Referring to FIG. 26 , when an inclination angle of 50° is provided, it is confirmed that a very uniform thin film can be obtained and a thin film with minimal surface defects can be obtained.

27 is an AFM image showing the surface uniformity of the light emitting layer according to Measurement Example 6 of the present invention.

Referring to FIG. 27 , when an inclination angle of 50° is given, the surface roughness of the light emitting layer of Preparation Example 3 is measured at nine points. It is confirmed that the thin film is uniformly formed with low surface roughness over the entire area.

28 is a graph illustrating external quantum efficiency and luminance characteristics of a light emitting device according to Measurement Example 6 of the present invention.

Referring to FIG. 28 , the external quantum efficiency and luminance characteristics of the light emitting device of Preparation Example 3 on which spin coating was performed to form the light emitting layer and the light emitting device of Preparation Example 4 on which bar coating was performed are compared.

The external quantum efficiency of the light emitting device on which the bar coating is performed is higher at low voltage than the light emitting device on which the spin coating is performed. This is due to the fact that the surface defects of the bar-coated light emitting layer are reduced compared to spin coating, and the density is improved. In addition, at a low luminance voltage, the light emitting layer formed by bar coating appears to be higher than that of the light emitting layer formed by spin coating.

In addition, there is no difference in external quantum efficiency between the two types of light emitting devices above 3.3 V, which corresponds to a relatively high voltage. In particular, the maximum value of the external quantum efficiency over the entire range is 23.26% of the sample of Preparation Example 4 on which the bar coating is performed, and the sample of Preparation Example 3 on which the spin coating is performed has a maximum value of 23.11%. That is, it can be seen that the light emitting device on which the bar coating is performed over the entire range has high external quantum efficiency.

However, those skilled in the art may selectively apply the process of forming the perovskite light emitting layer according to the operating conditions and specifications of the light emitting device. That is, if the operating voltage (voltage difference between the positive electrode and the negative electrode) is 3.5 V or less, high external quantum efficiency and luminance can be obtained by performing bar coating. If the operating voltage exceeds 3.5 V, spin coating is preferably performed. In addition, in the case of manufacturing a light emitting device having a large area, desired properties may be secured by performing bar coating.

As such, the perovskite light emitting device according to the present invention has a passivation layer including TBTB on the perovskite light emitting layer. Through this, the defects of the perovskite nanocrystal particles forming the light emitting layer are alleviated and the charge imbalance in the device is resolved, so that the luminous efficiency and maximum luminance are improved, so it can be usefully used instead of the conventional perovskite device .

On the other hand, the embodiments of the present invention disclosed in the present specification and drawings are merely presented as specific examples to aid understanding, and are not intended to limit the scope of the present invention. It will be apparent to those of ordinary skill in the art to which the present invention pertains that other modifications based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein.

100: perovskite nanocrystal particles
100': core-shell structured perovskite nanocrystal grains
100": Perovskite nanocrystal grains having a structure having a gradient composition
110: perovskite nanocrystal structure
111: doping element 115: core
120: organic ligand 130: shell
140: halide perovskite nanocrystal structure of a structure having a gradient composition

Claims (20)

Board;
a first electrode positioned on the substrate;
a perovskite thin film positioned on the first electrode;
a passivation layer positioned on the perovskite thin film and comprising at least one of Chemical Formulas 1 to 4; and
A perovskite light emitting device comprising a; a second electrode positioned on the passivation layer.
[Formula 1]

(In Formula 1, R ₁ , R ₃ or R ₅ is an alkyl group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, or hetero an alkenyl group, an aryl group or aryloxy group having 6 to 30 carbon atoms, or a heteroaryl group having 2 to 30 carbon atoms, R ₂ , R ₄ or R ₆ is a halogen or a halogenated alkyl group having 1 to 10 carbon atoms, 2 to 10 carbon atoms is a halogenated alkenyl group or a halogenated alkynyl group of
[Formula 2]

(In Formula 2, a ¹ to a ⁶ are each independently an alkyl group or alkoxy group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms. Alkenyl or heteroalkenyl group, aryl or aryloxy group having 6 to 30 carbon atoms, heteroaryl group having 2 to 30 carbon atoms, halogen, halogenated alkyl group having 1 to 10 carbon atoms, halogenated alkenyl group having 2 to 10 carbon atoms or halogenated is an alkynyl group)
[Formula 3]

(In Formula 3, X is a halogen element, and n is an integer of 1 to 100)
[Formula 4]

(In Formula 4, X is a halogen element, and n is an integer of 1 to 100) According to claim 1,
The organic semiconductor is tris(8-quinolinolate)aluminum {Tris-(8-hydroxyquinoline)aluminum, Alq3}, 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1, 2,4-triazole {3- (4-Bipenylyl) -4-phenyl-5-tert-butylphenyl-1, 2, 4-triazole ,TAZ}, tris-phenylquinoxaline 1,3,5-tris [ (3-phenyl-6-trifluoromethyl)quinoxalin-2-yl]benzene {Tris-Phenylquinoxalines 1,3,5-tris[(3-phenyl-6-trifluoromethyl)quinoxaline-2-yl]benzene, TPQ1 }, tris-phenylquinoxaline 1,3,5-tris[{3-(4-tert-butylphenyl)-6-trifluoromethyl}quinoxalin-2-yl]benzene {Tris-Phenylquinoxalines 1,3 ,5-tris[{3-(4-tert-butyl)-6-trifluoromethyl}quinoxaline-2-yl]benzene, TPQ2}, 4,7-diphenyl-1,10-phenanthroline (4,7- diphenyl-1,10-phenanthroline, Bphen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, BCP), 10-benzo [h] quinolinol-beryllium (10-benzo [h] quinolinol-beryllium, BeBq2), 8-hydroxy-2-methylquinoline- (4-phenylphenoxy) aluminum {(Bis ( 8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum, BAlq}, 4,4'-N,N'-dicarbazole-biphenyl (4,4'-N,N'-Dicabazol-biphenyl, CBP ), 9,10-di(naphthalen-2-yl)anthracene) {9,10-di(naphthalene-2-yl)anthracene, AND}, 4,4',4"-tris(N-carbazolyl)tri Phenylamine {4, 4', 4''-Tris(N-cabazolyl)triphenylamine, TCTA}, 1,3,5-tris(N-phenylbene) Zimidazol-2-yl)benzene {1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene, TPBI}, 3-tert-butyl-9,10-di(naphth-2-yl) Anthracene (TBADN) (1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-diyl)tris(diphenylphosphine oxide),2,4,6-tris[ 3-diphenylphosphinyl]phenyl]-1,3,5-triazine (PO-T2T), tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB) , 4,6-bis(3,5-di(pyridin-3-yl)phenyl)-2-methylpyrimidine (B3PYMPM) and 2-[4-(9,10-di-naphthalen-2-yl-anthracene) -2-yl)-phenyl]-1-phenyl-1H-benzoimidazole (ZADN) comprising at least one selected from
The polymer is poly(methyl methacrylate) {Poly(Methyl Methacrylate, PMMA), poly(ethyl methacrylate) {Poly(ethyl methacrylate), PEMA}, poly(butyl methacrylate) {Poly(butyl methacrylate, PBMA) ), poly (2-ethyl-2-oxazoline {Poly (2-ethyl-2-oxazoline, PEOXA}), polyacrylamide (Polyacrylamide PAM) and polyethylene oxide (Polyethylene oxide, PEO) containing at least one selected from Perovskite light emitting device, characterized in that. The perovskite light emitting device according to claim 1, wherein the passivation layer comprises a compound represented by the following formula (5).
[Formula 5]

In Formula 5, X ₁ , X ₂ or X ₃ is F, Cl, Br, or I. The perovskite light emitting device according to claim 3, wherein the X ₁ , X ₂ and X ₃ are the same halogen element. According to claim 1,
When the compound represented by Formula 2, Formula 3, or Formula 4 is used in the passivation layer, an organic material comprising at least one selected from organic semiconductors and polymers for at least one compound of Formulas 2 to 4 A perovskite light emitting device, characterized in that it contains a molar ratio of 1: 0.3 to 1: 10. According to claim 1,
A hole injection layer or an electron transport layer is further included between the first electrode and the perovskite thin film, or between the passivation layer and the second electrode. According to claim 1, wherein the perovskite thin film comprises perovskite nanocrystal particles, the perovskite nanocrystal particles are bonded to the perovskite nanocrystals and the surface of the perovskite nanocrystals A perovskite light emitting device comprising an organic ligand. The perovskite light emitting device according to claim 7, wherein the perovskite nanocrystal particles have a core-shell structure. The perovskite light emitting device according to claim 7, wherein the perovskite nanocrystal particles have a gradient composition. The perovskite light emitting device according to claim 7, wherein the perovskite nanocrystal particles are doped with n-type or p-type. The perovskite light emitting device according to claim 7, wherein the perovskite nanocrystal particles have a diameter larger than the exciton bore diameter. forming a first electrode on a substrate;
forming a perovskite thin film on the first electrode;
forming a passivation layer comprising the following (1) or (2) on the perovskite thin film; and
A method of manufacturing a perovskite light emitting device comprising the step of forming a second electrode on the passivation layer.
(1) a compound represented by the following formula (1)
[Formula 1]

(In Formula 1, R ₁ , R ₃ or R ₅ is an alkyl group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, or hetero an alkenyl group, an aryl group or aryloxy group having 6 to 30 carbon atoms, or a heteroaryl group having 2 to 30 carbon atoms, R ₂ , R ₄ or R ₆ is a halogen or a halogenated alkyl group having 1 to 10 carbon atoms, 2 to 10 carbon atoms is a halogenated alkenyl group or a halogenated alkynyl group of
(2) a compound represented by Formula 2, Formula 3, or Formula 4; and an organic material comprising at least one selected from organic semiconductors and polymers; a mixture of mixtures
[Formula 2]

(In Formula 2, a ¹ to a ⁶ are each independently an alkyl group or alkoxy group having 1 to 10 carbon atoms, an alkenyl group or alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms. Alkenyl or heteroalkenyl group, aryl or aryloxy group having 6 to 30 carbon atoms, heteroaryl group having 2 to 30 carbon atoms, halogen, halogenated alkyl group having 1 to 10 carbon atoms, halogenated alkenyl group having 2 to 10 carbon atoms or halogenated is an alkynyl group)
[Formula 3]

(In Formula 3, X is a halogen element, and n is an integer of 1 to 100)
[Formula 4]

(In Formula 4, X is a halogen element, and n is an integer of 1 to 100) The method of claim 12, wherein the perovskite thin film is formed through spin coating. The method of claim 13, wherein the formation of the perovskite thin film,
introducing a solution of perovskite nanocrystals on the first electrode;
Giving a holding time to the introduced perovskite nanocrystal particle solution; and
After the holding time is over, the method of manufacturing a perovskite light emitting device comprising the step of applying the perovskite nanocrystalline particle solution through a spin coater to proceed with spin coating. 15. The method of claim 14, wherein the holding time is 2 minutes to 50 minutes. The method of claim 12, wherein the perovskite thin film is formed through bar coating. 17. The method of claim 16, wherein the bar coating is
introducing a solution of perovskite nanocrystals on the first electrode;
tilting the first electrode into which the perovskite nanocrystal solution is introduced by giving an inclination angle with respect to the horizontal plane; and
Method of manufacturing a perovskite light emitting device comprising the step of performing bar coating on the inclined first electrode and the perovskite nanocrystal particle solution. The method of claim 17, wherein a holding time is given after the step of introducing the perovskite nanocrystal particle solution. [13] The method of claim 12, wherein the passivation layer comprises a compound represented by the following formula (5):
[Formula 5]

In Formula 5, X ₁ , X ₂ or X ₃ is F, Cl, Br, or I. 13. The method of claim 12, wherein the organic semiconductor is tris(8-quinolinolate)aluminum {Tris-(8-hydroxyquinoline)aluminum, Alq3}, 3-(4-biphenylyl)-4-phenyl-5-tert -Butylphenyl-1,2,4-triazole {3-(4-Bipenylyl)-4-phenyl-5-tert-butylphenyl-1, 2, 4-triazole ,TAZ}, tris-phenylquinoxaline 1, 3,5-tris[(3-phenyl-6-trifluoromethyl)quinoxalin-2-yl]benzene {Tris-Phenylquinoxalines 1,3,5-tris[(3-phenyl-6-trifluoromethyl)quinoxaline-2 -yl]benzene, TPQ1}, tris-phenylquinoxaline 1,3,5-tris[{3-(4-tert-butylphenyl)-6-trifluoromethyl}quinoxalin-2-yl]benzene { Tris-Phenylquinoxalines 1,3,5-tris[{3-(4-tert-butyl)-6-trifluoromethyl}quinoxaline-2-yl]benzene, TPQ2}, 4,7-diphenyl-1,10-phenanthro Lin (4,7-diphenyl-1,10-phenanthroline, Bphen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (2,9-dimethyl-4,7-diphenyl- 1,10-phenanthroline , BCP), 10-benzo [h] quinolinol-beryllium (10-benzo [h] quinolinol-beryllium, BeBq2), 8-hydroxy-2-methylquinoline- (4-phenylphenoxy) ) aluminum {(Bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum, BAlq}, 4,4'-N,N'-dicarbazole-biphenyl (4,4'-N,N') -Dicabazol-biphenyl, CBP), 9,10-di(naphthalene-2-yl)anthracene) {9,10-di(naphthalene-2-yl)anthracene, AND}, 4, 4',4"-tris ( N-carbazolyl) triphenylamine {4, 4', 4''-Tris (N-cabazolyl) triphenylamine, TCTA}, 1,3, 5-tris(N-phenylbenzimidazol-2-yl)benzene {1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene, TPBI}, 3-tert-butyl-9,10-di (naphth-2-yl)anthracene (TBADN) and 2-[4-(9,10-di-naphthalen-2-yl-anthracen-2-yl)-phenyl]-1-phenyl-1H-benzoimidazole (ZADN) comprising at least one selected from,
The polymer is poly(methyl methacrylate) {Poly(Methyl Methacrylate, PMMA), poly(ethyl methacrylate) {Poly(ethyl methacrylate), PEMA}, poly(butyl methacrylate) {Poly(butyl methacrylate, PBMA) ), poly (2-ethyl-2-oxazoline {Poly (2-ethyl-2-oxazoline, PEOXA}), polyacrylamide (Polyacrylamide PAM) and polyethylene oxide (Polyethylene oxide, PEO) containing at least one selected from Method of manufacturing a perovskite light emitting device, characterized in that.

Images