Method for observing auger recombination of quantum dots

Abstract

The invention relates to a method for observing Auger recombination of quantum dots. A method for observing Auger recombination of quantum dots includes: preparing an EOD device, where the EOD device includes quantum dots; applying a current to the EOD device; and observing the negative tri-excitons formed in the EOD device. Further, a method for observing Auger recombination of quantum dots includes: preparing an HOD device, where the HOD device includes quantum dots; applying a current to the HOD device; and observing the positive triexcitons formed in the HOD device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Korean Patent Application No. 10-2023-0072771 filed on Jun. 7, 2023 and all benefits derived therefrom, the entire contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates to a method for observing Auger recombination of quantum dots, and more particularly to a method for observing Auger recombination of quantum dots in electron-only devices (EOD) and hole-only devices (HOD). Background Art

[0004] The light emitting device includes an anode, a cathode, and a light emitting layer formed therebetween. When excitons formed by the recombination of holes injected from the anode and electrons injected from the cathode in the light emitting layer fall from an excited state to a ground state, light is emitted.

[0005] Since light emitting devices can be operated at a low voltage and can be configured in a lightweight and flat form, the scope of their applications is expanding from personal portable devices to televisions due to their excellent characteristics such as viewing angle, contrast, response speed, etc.

[0006] Auger recombination can occur during the formation of excitons in a light-emitting device.

[0007] Auger recombination is a phenomenon in which light is not emitted to the outside when electrons and holes are recombined and energy is transferred to other excitons nearby.

[0008] That is, since no light is emitted, it becomes a major obstacle to improving the efficiency of quantum dot-based light-emitting devices, especially displays. Summary of the invention

[0009] Embodiments of the present invention provide a method for observing Auger recombination of quantum dots by observing negative trions or positive trions.

[0010] In an embodiment, a method for observing Auger recombination of quantum dots includes preparing an electron-only device (also referred to as an "EOD device"), applying a current to the EOD device, and observing negative triexcitons formed in the EOD device.

[0011] In an embodiment, in the step of applying a current to the EOD device, the applied current may be about 0.5 A / cm 2 or smaller.

[0012] In an embodiment, observing negative triexcitons formed in the EOD device may be performed by comparing the photoluminescence (PL) intensity of the EOD device before and after applying a current to the EOD device.

[0013] In an embodiment, the EOD device may include a first electrode and a second electrode disposed to face each other, a light emitting layer located between the first electrode and the second electrode, a first electron transport layer located between the first electrode and the light emitting layer, and a second electron transport layer located between the second electrode and the light emitting layer.

[0014] In an embodiment, the light emitting layer may have a ~Approx. Thickness.

[0015] In an embodiment, the first electron transport layer and the second electron transport layer may include different materials.

[0016] In an embodiment, the first electron transport layer and the second electron transport layer may include the same material.

[0017] In an embodiment, the quantum dots may include a plurality of selected from the group consisting of CdSe / CdS, CdS / CdSe / CdS, CdSe / Cd 1-X Zn X Se / CdZnS and ZnSe 1-X Te X / ZnSe / ZnS.

[0018] In an embodiment, the first electron transport layer may include ZnO.

[0019] In an embodiment, the second electron transport layer may include TPBi.

[0020] In an embodiment, a method for observing Auger recombination of quantum dots includes preparing a hole-only device (also referred to as a "HOD device"), applying a current to the HOD device, and observing positive triexcitons formed in the HOD device.

[0021] In an embodiment, in the step of applying a current to the HOD device, the applied current may be about 0.5 A / cm 2 or smaller.

[0022] In an embodiment, observing positive triexcitons formed in the HOD device may be performed by comparing the PL intensity of the HOD device before and after applying a current to the HOD device.

[0023] In an embodiment, the HOD device includes a first electrode and a second electrode disposed to face each other, a light emitting layer located between the first electrode and the second electrode, a first hole transport layer located between the first electrode and the light emitting layer, and a second hole transport layer located between the second electrode and the light emitting layer.

[0024] In an embodiment, the light emitting layer may have a ~Approx. Thickness.

[0025] In an embodiment, the first hole transport layer and the second hole transport layer may include different materials.

[0026] In an embodiment, the first hole transport layer and the second hole transport layer may include the same material.

[0027] In an embodiment, the quantum dots may include a plurality of selected from the group consisting of CdSe / CdS, CdS / CdSe / CdS, CdSe / Cd 1-X Zn X Se / CdZnS and ZnSe 1-X Te X / ZnSe / ZnS.

[0028] In an embodiment, the first hole transport layer may include PEDOT:PSS and TFB.

[0029] In an embodiment, the second hole transport layer may include CBP.

[0030] According to an embodiment, a method of observing Auger recombination of a quantum dot by observing a negative triexciton or a positive triexciton is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A stacked structure of an EOD device according to an embodiment is shown.

[0032] Figure 2 An observation process of Auger recombination using an EOD device according to an embodiment is explained.

[0033] Figure 3 According to the embodiment Figure 2 Energy band diagram and electron movement of the EOD device.

[0034] Figure 4 Graphs illustrating measurement results of PL intensity of an EOD device before operation and after charging according to an embodiment.

[0035] Figure 5 A stack structure of a HOD device according to an embodiment is explained.

[0036] Figure 6An observation process of Auger recombination using a HOD device according to an embodiment is explained.

[0037] Figure 7 According to the embodiment Figure 6 Energy band diagram and charge movement of the HOD device.

[0038] Figure 8 is a graph showing measurement results of PL intensity of a HOD device before operation and after charging according to an embodiment.

[0039] Fig. 9 is a graph showing negative triexcitons observed using an EOD device according to an embodiment and positive triexcitons observed using an HOD device according to an embodiment. DETAILED DESCRIPTION

[0040] Hereinafter, various embodiments of the present invention are described in detail with reference to the accompanying drawings so that those having ordinary skill in the art can easily implement the present invention.

[0041] The present invention may be embodied in various different forms and is not limited to the examples described herein.

[0042] In order to clearly explain the present invention, parts irrelevant to the explanation have been omitted, and the same or similar constituent elements are attached with the same reference numerals throughout the specification.

[0043] In addition, since the size (for example, thickness) of each component shown in the drawings is arbitrarily shown for convenience of explanation, the present invention is not limited to the size (for example, thickness) of each component shown.

[0044] In the drawings, the thickness is shown exaggerated in order to clearly show each layer and region.

[0045] Also, in the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0046] In addition, when a component (such as a layer, film, region or panel) is referred to as being “on” or “on” another component (such as a layer, film, region or panel), this not only includes the case where it is “directly on” the other component (such as a layer, film, region or panel) but also includes the case where there are other components in between them.

[0047] In contrast, when an element is referred to as being “directly on” another element, it means that there are no other elements present in between.

[0048] In addition, “on” or “over” a reference component means located above or below the reference component, and does not necessarily mean located “on” or “over” the reference component in an opposite direction of gravity.

[0049] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of this article, the first element, component, region, layer or part discussed below may be referred to as a second element, component, region, layer or part.

[0050] The terms used in this article are only used for the purpose of describing specific embodiments and are not intended to be limiting. As used in this article, "a", "an", "the" and "at least one" do not represent a limit on quantity and are intended to include both the singular and the plural, unless the context clearly indicates otherwise. For example, "element" has the same meaning as "at least one element", unless the context clearly indicates otherwise. "At least one" is not interpreted as being limited to "a" or "an". "Or" means "and / or". As used in this article, the term "and / or" includes any and all combinations of one or more of the relevant listed items.

[0051] In addition, throughout the specification, when a certain component is referred to as “comprising”, it may further include other components rather than excluding other components unless there is a clear contrary description.

[0052] In addition, throughout the specification, when “on a plane” is mentioned, it means when the target component is viewed from above, and when “on a cross section” is mentioned, it means when a cross section of the target component cut vertically is viewed from the side.

[0053] As used herein, "about" or "approximately" includes the stated value and means within an acceptable range of deviation of the particular value as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0054] Unless otherwise defined, all terms (including technical and scientific terms) used in this article have the same meaning as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. It will be further understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant field and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such in this article.

[0055] Embodiments are described herein with reference to cross-sectional views as schematic diagrams of ideal embodiments. As such, variations in the illustrated shapes due to, for example, manufacturing techniques and / or tolerances should be expected. Therefore, the embodiments described herein should not be construed as being limited to the specific shapes of the zones as illustrated herein, but rather include deviations in shapes due to, for example, manufacturing. For example, a zone illustrated or described as flat may typically have rough and / or nonlinear features. Moreover, the illustrated sharp corners may be rounded. Therefore, the zones illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shapes of the zones and are not intended to limit the scope of the invention.

[0056] Hereinafter, a method for observing Auger recombination of quantum dots according to an embodiment will be described.

[0057] In the method for observing Auger recombination of quantum dots according to an embodiment, Auger recombination of quantum dots is observed using an electron-only device (EOD) or a hole-only device (HOD).

[0058] Next, the EOD device will be described.

[0059] Figure 1 A stacked structure of an EOD device according to an embodiment is shown.

[0060] In the embodiments and with reference to Figure 1 The EOD device includes a first electrode 191 , a second electrode 270 , and a light emitting layer EML located between the first electrode 191 and the second electrode 270 .

[0061] Also, in an embodiment, the first electron transport layer ETL1 is located between the first electrode 191 and the light emitting layer EML, and the second electron transport layer ETL2 is located between the second electrode 270 and the light emitting layer EML.

[0062] In other words, according to an embodiment, the EOD device has the first electron transport layer ETL1 and the second electron transport layer ETL2 located on both sides of the light emitting layer EML.

[0063] In an embodiment, the first electron transport layer ETL1 and the second electron transport layer ETL2 may include different materials, or they may include the same material.

[0064] In an implementation, the first electrode 191 may include a transparent conductive oxide.

[0065] In an implementation, the first electrode 191 may include indium tin oxide (ITO).

[0066] In an embodiment, the second electrode 270 may include one or more metals (such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, lead, cesium, barium, molybdenum, etc.) or alloys thereof or multilayer structures of materials (such as LiF / Al, Li 2 O / Al, LiF / Ca and MoO x / Al), but not limited to these.

[0067] In an embodiment, the second electrode 270 may be a LiF / Al laminate structure or a MoO x / Al laminated structure, wherein x can be 1-4.

[0068] In an embodiment, the light emitting layer EML may include quantum dots.

[0069] In an embodiment, the diameter of the quantum dot may be, for example, about 1 nm to about 10 nm.

[0070] In an embodiment, the quantum dots may be synthesized by a wet chemical process, a metal organic chemical vapor deposition (MOCVD) process, a molecular beam epitaxy (MBE) process, or a process similar thereto.

[0071] In an embodiment, a wet chemical process is a method of growing quantum dot particle crystals after mixing an organic solvent and a precursor material.

[0072] In an embodiment, when the quantum dot particle crystal grows, the organic solvent naturally acts as a dispersant coordinated on the surface of the quantum dot particle crystal and regulates the growth of the crystal. Therefore, the wet chemical process is more convenient than vapor deposition methods such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE), and the growth of quantum dot particle crystals can be controlled through a low-cost process.

[0073] In an embodiment, the quantum dots are: Group III-VI semiconductor compounds; Group II-VI semiconductor compounds; Group III-V semiconductor compounds; Group I-III-VI semiconductor compounds; Group IV-VI semiconductor compounds; Group IV elements or compounds; or any combination thereof.

[0074] In an embodiment, examples of Group II-VI semiconductor compounds include binary compounds such as CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, and MgS, etc., ternary compounds such as CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS , CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, etc.), quaternary compounds (such as CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, etc.) or any combination thereof.

[0075] Moreover, in an embodiment, examples of Group III-V semiconductor compounds include binary compounds (such as GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs and InSb, etc.), ternary compounds (such as GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InGaP, InNP, InAlP, InNAs, InNSb, InPAs and InPSb, etc.), quaternary compounds (such as GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, etc.) or any combination thereof.

[0076] Meanwhile, in an embodiment, the Group III-V semiconductor compound may further include a Group II element.

[0077] In an embodiment, examples of the Group III-V semiconductor compound further including the Group II element may include InZnP, InGaZnP, InAlZnP, and the like.

[0078] In an embodiment, examples of III-VI semiconductor compounds include binary compounds such as GaS, Ga 2 S 3 ,GaSe,Ga 2 Se 3 、GaTe、InS、InSe、In 2 Se3 and InTe, etc.), ternary compounds (such as InGaS 3 and InGaSe 3 etc.) or any combination thereof.

[0079] In an embodiment, examples of Group I-III-VI semiconductor compounds include ternary compounds such as AgInS, AgInS 2 、AgInSe 2 、AgGaS、AgGaS 2 、AgGaSe 2 、CuInS、CuInS 2 、CuInSe 2 、CuGaS 2 、CuGaSe 2 、CuGaO 2 、AgGaO 2 and AgAlO 2 etc.), quaternary compounds (such as AgInGaS 2 and AgInGaSe 2 etc.) or any combination thereof.

[0080] In an embodiment, examples of Group IV-VI semiconductor compounds include binary compounds (such as SnS, SnSe, SnTe, PbS, PbSe and PbTe, etc.), ternary compounds (such as SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe and SnPbTe, etc.), quaternary compounds (such as SnPbSSe, SnPbSeTe and SnPbSTe, etc.) or any combination thereof.

[0081] In embodiments, the Group IV element or compound may be a single element material (such as Si or Ge), a binary compound (such as SiC and SiGe), or any combination thereof.

[0082] In an embodiment, each element included in the multi-element compound such as a binary compound, a ternary compound, and a quaternary compound may be present in the particle at a uniform concentration or a non-uniform concentration.

[0083] That is, in an embodiment, a chemical formula means the types of elements included in a compound, and the ratio of elements in the compound may be different.

[0084] For example, in an embodiment, AgInGaS 2 Can mean AgIn x Ga 1-x S 2 (where 0 <x<1)。

[0085] On the other hand, in an embodiment, the quantum dot may have a single structure in which the concentration of each element included in the quantum dot is uniform, or a core-shell dual structure.

[0086] For example, in an embodiment, a material included in the core and a material included in the shell may be different from each other.

[0087] In embodiments, the shell of a quantum dot may serve as a protective layer for maintaining semiconductor properties by preventing chemical denaturation of the core and / or as a charging layer for imparting electrophoretic properties to the quantum dot.

[0088] In embodiments, the shell may be a single layer or multiple layers.

[0089] In an embodiment, the interface between the core and the shell may have a concentration gradient in which the concentration of the element present in the shell decreases toward the core.

[0090] In an embodiment, examples of the shell of the quantum dot include metal or non-metal oxides, semiconductor compounds, or combinations thereof.

[0091] In an embodiment, examples of metal or non-metal oxides include binary compounds such as SiO 2 、Al 2 O 3 、TiO 2 、ZnO、MnO、Mn 2 O 3 , Mn 3 O 4 , CuO, FeO, Fe 2 O 3 , Fe 3 O 4 , CoO, Co 3 O 4 and NiO, etc.), ternary compounds (such as MgAl 2 O 4 、CoFe 2 O 4 、NiFe 2 O 4 and CoMn 2 O 4 etc.) or any combination thereof.

[0092] In embodiments, examples of semiconductor compounds include Group III-VI semiconductor compounds, Group II-VI semiconductor compounds, Group III-V semiconductor compounds, Group I-III-VI semiconductor compounds, Group IV-VI semiconductor compounds, or any combination thereof as described herein.

[0093] For example, in an embodiment, the semiconductor compound may be CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnSeS, ZnTeS, GaAs, GaP, GaS, GaSe, AgGaS, AgGaS 2 , GaSb, HgS, HgSe, HgTe, InAs, InP, InGaP, InSb, AlAs, AlP, AlSb or any combination thereof.

[0094] In an embodiment, the quantum dots may include CdSe / CdS, CdSe / Cd 1-X Zn X Se / CdZnS and ZnSe 1-X Te X / ZnSe / ZnS, one or more of which 0 <X≤1。

[0095] In an embodiment, it is preferred that the thickness of the light emitting layer EML does not exceed the thickness of the three-layer quantum dots.

[0096] That is, in an embodiment, the light emitting layer EML may have about ~Approx. Thickness.

[0097] In an embodiment, when the light emitting layer EML is thick, current is hindered during measurement for observing Auger recombination, which is not preferable.

[0098] In an embodiment, the first electron transport layer ETL1 and the second electron transport layer ETL2 may include ZnO or TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene), but are not limited thereto.

[0099] In an embodiment, other materials may be used as long as they are materials having an energy level similar to that of ZnO or materials having an energy level similar to that of TPBi.

[0100] In an embodiment, by injecting charge into the EOD device, Auger recombination can be observed without degrading the properties of the quantum dots.

[0101] In an embodiment, Auger recombination is a phenomenon in which light is not emitted to the outside when electrons and holes are recombined and energy is transferred to other excitons nearby.

[0102] That is, in an embodiment, since no light is emitted, it becomes a major obstacle to improving the efficiency of quantum dot-based light-emitting devices, especially displays.

[0103] In embodiments, measuring the extent of Auger recombination is important for measuring the efficiency of a light emitting device.

[0104] Accordingly, in an embodiment, a method for observing Auger recombination includes observing Auger recombination of quantum dots using an electron-only device (EOD) or a hole-only device (HOD).

[0105] Figure 2 An observation process of Auger recombination using an EOD device according to an embodiment is explained.

[0106] Figure 2 An EOD device having a stack structure of ITO / ZnO / QD / TPBi / LiF / Al according to an embodiment is shown.

[0107] Figure 3 According to the embodiment Figure 2 Energy band diagram and electron movement of the EOD device.

[0108] In the embodiments and with reference to Figure 2 , when electrons are injected into the EOD device, the light emitting layer EML is charged.

[0109] In an embodiment, light is irradiated from the outside in this electron injection and charging state.

[0110] In an embodiment, light irradiation may be performed using laser light.

[0111] In an embodiment, by such light irradiation, Figure 2 As shown in the state (D), a negative triexciton is formed.

[0112] In an embodiment, a negative triexciton means two electrons and one hole.

[0113] In embodiments, the extent of Auger recombination may be measured by observing the negative triexcitons thereby formed.

[0114] In an embodiment, after the negative triexciton is formed, light emission may be performed, and the degree of Auger recombination may be measured by measuring the degree of light emission.

[0115] Figure 4 Graphs illustrating measurement results of PL intensity of an EOD device before operation and after charging according to an embodiment.

[0116] In the embodiments and with reference to Figure 4 The extent of Auger recombination can be measured by the difference in photoluminescence (PL) intensity before operation and after charging.

[0117] In an embodiment, if Figure 4 As shown, the PL intensity before the operation is given by Figure 2 The hv2 in the process indicates the measurement result of the luminescence, and the PL intensity after charging is given by Figure 2Hv2 and Hv3 indicate the measurement results of the luminescence during the process.

[0118] Therefore, according to an embodiment, through this comparison, the degree of luminescence in the process indicated by hv3 can be measured.

[0119] Among conventional Auger recombination analysis methods, photochemical and electrochemical methods have a problem in that, in addition to injecting additional charges, the photochemical and electrochemical methods cannot accurately observe multi-exciton dynamics because chemical reactions occur on the surface.

[0120] However, the method for observing Auger recombination according to the embodiment can measure the degree of Auger recombination without a surface chemical reaction.

[0121] In addition, conventional optical doping methods cannot observe positive triexcitons, but in the embodiments of the present invention, there is an advantage in that positive triexcitons can be observed using a HOD device.

[0122] Figure 5 A stacked structure of a HOD device according to an embodiment is shown.

[0123] In the embodiments and with reference to Figure 5 The HOD device includes a first electrode 191 , a second electrode 270 , and a light emitting layer EML located between the first electrode 191 and the second electrode 270 .

[0124] Also, in an embodiment, the first hole transport layer HTL1 is located between the first electrode 191 and the emission layer EML, and the second hole transport layer HTL2 is located between the second electrode 270 and the emission layer EML.

[0125] In other words, in an embodiment, the first hole transport layer HTL1 and the second hole transport layer HTL2 are located at both sides of the emission layer EML.

[0126] In an embodiment, the first hole transport layer HTL1 and the second hole transport layer HTL2 may contain different materials, or they may contain the same material.

[0127] In the embodiment, the first electrode 191, the second electrode 270, and the light emitting layer EML are described as follows. Figure 1 The description of the first electrode 191, the second electrode 270 and the light emitting layer EML are the same.

[0128] Detailed description of the same constituent elements is omitted.

[0129] In an embodiment, the first hole transport layer HTL1 and the second hole transport layer HTL2 may include one or more of PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid), TFB (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl))diphenylamine)]), and CBP (4,4′-bis(N-carbazolyl)-1,1′-biphenyl), but are not limited thereto.

[0130] In an embodiment, through the process of injecting charge into the HOD device, Auger recombination can be observed without degrading the properties of the quantum dots.

[0131] In addition, in the embodiment, positive triexcitons that were difficult to observe in the past can be observed through charge injection of the HOD device.

[0132] Figure 6 An observation process of Auger recombination using a HOD device according to an embodiment is explained.

[0133] Figure 6 The ITO / PEDOT:PSS / TFB / QD / CBP / MoO x An implementation method of a HOD device with a stacked structure of / Al.

[0134] Figure 7 According to the embodiment Figure 6 Energy band diagram and charge movement of the HOD device.

[0135] refer to Figure 6 , when charges are injected into the HOD device, the light emitting layer EML is charged.

[0136] In an embodiment, light is irradiated from the outside in this electron injection and charging state.

[0137] In an embodiment, light irradiation may be performed using laser light.

[0138] In an embodiment, by such light irradiation, Figure 6 The state (D) shows the formation of positive triexcitons.

[0139] In an embodiment, a positive triexciton means two holes and one charge.

[0140] Therefore, according to an embodiment, the extent of Auger recombination can be measured by observing the positive triexcitons formed thereby.

[0141] In an embodiment, after the positive triexciton is formed, light emission may be performed, and the degree of Auger recombination may be measured by measuring the degree of light emission.

[0142] Figure 8is a graph showing measurement results of PL intensity of a HOD device before operation and after charging according to an embodiment.

[0143] In the embodiments and with reference to Figure 8 , the extent of Auger recombination can be measured by the difference in PL intensity before operation and after charging.

[0144] In an embodiment, Figure 6 In the example, the PL intensity before the operation is given by Figure 6 The hv2 in the process indicates the measurement result of the luminescence, and the PL intensity after the operation (after charging) is given by Figure 6 Hv2 and Hv4 indicate the measurement results of the luminescence during the process.

[0145] Therefore, according to an embodiment, through this comparison, the degree of luminescence in the process indicated by hv4 can be measured.

[0146] Fig. 9 Graphs illustrating negative triexcitons observed using an EOD device according to an embodiment and positive triexcitons observed using an HOD device according to an embodiment.

[0147] pass Fig. 9 It was confirmed that negative triexcitons and positive triexcitons can be observed using the EOD device and the HOD device, respectively, according to the embodiment.

[0148] Thus, according to the embodiment, Auger recombination of quantum dots included in the light emitting device may be observed.

[0149] In particular, although positive triexcitons cannot be observed in the case of the conventional Auger recombination measurement method, the amount of positive triexcitons can be observed in the embodiment.

[0150] In addition, the ZnSe with high conduction band of the light emitting layer 1-X Te X The quantum dots of the series have a very unstable negative triexciton state and cannot be observed by conventional methods. However, in the embodiment, due to the high energy level of TPBi included in the electron transport layer, electrons are confined in the quantum dot layer, so that negative triexcitons can be observed.

[0151] In an embodiment, the EOD device and the HOD device according to the embodiment have about 20 nm of ZnO, about 30 nm of TPBi, about 10 nm of MoO x , PEDOT:PSS of about 20 nm, TFB of about 20 nm, CBP of about 60 nm, and Al of about 110 nm are manufactured and used, but the thickness of each layer is not limited thereto.

[0152] In an embodiment, it is preferred that the thickness of each layer except the first electrode and the second electrode does not exceed about 100 nm.

[0153] In addition, when measuring Auger recombination according to the embodiment, an excessively high current may damage the EOD device or the HOD device, and the applied current is preferably about 0.5 A / cm 2 or smaller.

[0154] If the applied current is greater than 0.5A / cm 2 , it is not preferred because the EOD device or the HOD device may be damaged.

[0155] Although the present invention has been specifically shown and described with reference to embodiments of the present invention, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit or scope of the present invention. Therefore, it should be understood that the foregoing is an illustration of various embodiments and is not to be construed as being limited to the specific embodiments disclosed, and modifications to the present invention are intended to be included within the scope of the present invention. Moreover, embodiments or portions of embodiments may be combined in whole or in part without departing from the scope of the present invention.

Claims

1. A method for observing Auger recombination in quantum dots, include: preparing an electron-only device, wherein the electron-only device comprises quantum dots; applying an electric current to the electronic device; as well as Negative triexcitons were observed to be formed in the electron-only device.

2. The method according to claim 1, wherein Applying current includes applying 0.5A / cm 2 or less current.

3. The method according to claim 1, wherein Observing negative triexcitons includes comparing photoluminescence intensity of the electron-only device before and after applying the current to the electron-only device.

4. The method according to claim 1, wherein The electronic device only include: a first electrode and a second electrode disposed to face each other; a light emitting layer located between the first electrode and the second electrode; a first electron transport layer located between the first electrode and the light emitting layer; as well as A second electron transport layer is located between the second electrode and the light emitting layer.

5. The method according to claim 4, wherein The light-emitting layer has The thickness is within the range of .

6. The method according to claim 4, wherein The first electron transport layer and the second electron transport layer include different materials.

7. The method according to claim 4, wherein The first electron transport layer and the second electron transport layer include the same material.

8. The method according to claim 4, wherein The quantum dots include CdSe / CdS, CdS / CdSe / CdS, CdSe / Cd 1-X Zn X Se / CdZnS and ZnSe 1-X Te X At least one of / ZnSe / ZnS.

9. The method according to claim 8, wherein The first electron transport layer includes ZnO.

10. The method according to claim 9, wherein The second electron transport layer includes TPBi.

11. A method for observing Auger recombination in quantum dots. include: preparing a hole-only device, wherein the hole-only device comprises quantum dots; applying a current to the hole-only device; as well as Positive triexcitons were observed to be formed in the hole-only device.

12. The method according to claim 11, in: Applying current includes applying 0.5A / cm 2 or less current.

13. The method according to claim 11, wherein Observing positive triexcitons includes comparing photoluminescence intensity of the hole-only device before and after applying the current to the hole-only device.

14. The method according to claim 11, wherein The hole-only device include: a first electrode and a second electrode disposed to face each other; a light emitting layer located between the first electrode and the second electrode; a first hole transport layer located between the first electrode and the light-emitting layer; as well as A second hole transport layer is located between the second electrode and the light emitting layer.

15. The method according to claim 14, wherein The light-emitting layer has The thickness is within the range of .

16. The method according to claim 14, wherein The first hole transport layer and the second hole transport layer include different materials.

17. The method according to claim 14, wherein The first hole transport layer and the second hole transport layer include the same material.

18. The method according to claim 14, wherein The quantum dots include CdSe / CdS, CdS / CdSe / CdS, CdSe / Cd 1-X Zn X Se / CdZnS and ZnSe 1-X Te X At least one of / ZnSe / ZnS.

19. The method according to claim 18, wherein The first hole transport layer includes PEDOT:PSS and TFB.

20. The method according to claim 19, wherein The second hole transport layer includes CBP.

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