CN115715100A

CN115715100A - Light-emitting device, manufacturing method thereof and display panel

Info

Publication number: CN115715100A
Application number: CN202110961653.6A
Authority: CN
Inventors: 周礼宽; 杨一行
Original assignee: TCL Technology Group Co Ltd
Current assignee: TCL Technology Group Co Ltd
Priority date: 2021-08-20
Filing date: 2021-08-20
Publication date: 2023-02-24

Abstract

The embodiment of the invention discloses a light-emitting device, a manufacturing method thereof and a display panel; the light-emitting device comprises a light-emitting material layer and an electron transmission layer positioned on the light-emitting material layer; the electron transport layer comprises a sulfur-containing ZnO layer, and coordination bonds are connected between sulfur elements in the sulfur-containing ZnO layer and the first metal elements; according to the embodiment of the invention, the sulfur element on the sulfur-containing ZnO layer is combined with the first metal element on the surface of the luminescent material layer to form the coordination bond, so that a new electron transmission path is formed, the interface barrier is reduced, the electron transmission rate from the electron transmission layer to the luminescent material layer is accelerated, and the photoelectric property and the stability of the luminescent device are favorably improved.

Description

Light-emitting device, manufacturing method thereof and display panel

Technical Field

The invention relates to the field of display, in particular to a light-emitting device, a manufacturing method thereof and a display panel.

Background

In recent years, the inorganic nano-particle zinc oxide film serving as an electron transport layer of a quantum dot light-emitting diode device can provide better display color gamut and longer light-emitting life, and has incomparable advantages compared with the traditional organic material.

Therefore, a light emitting device, a method for manufacturing the same, and a display panel are needed to solve the above-mentioned problems.

Disclosure of Invention

The embodiment of the invention provides a light-emitting device, a manufacturing method thereof and a display panel, which can solve the technical problems that the interface barrier between a zinc oxide film and a quantum dot light-emitting diode device is high and the working efficiency of quantum dots is low at present.

The embodiment of the invention provides a light-emitting device, which comprises a light-emitting material layer and an electron transmission layer positioned on the light-emitting material layer;

the light-emitting material layer contains a first metal element, the electron transport layer comprises a sulfur-containing ZnO layer, and at least part of sulfur in the sulfur-containing ZnO layer is connected with a coordination bond with the first metal element.

In one embodiment, a covalent bond is connected between the sulfur element in the sulfur-containing ZnO layer and the zinc element in the sulfur-containing ZnO layer.

In one embodiment, the electron transport layer further comprises a ZnS layer between the sulfur-containing ZnO layer and the light emitting material layer.

In one embodiment, the content of the sulfur element in the sulfur-containing ZnO layer gradually decreases in a direction away from the luminescent material layer.

In one embodiment, in the sulfur-containing ZnO layer, the molar ratio between sulfur element and oxygen element is 1.

In one embodiment, the light emitting device further includes a cathode layer on the electron transport layer at a side away from the light emitting material layer, a hole function layer on the light emitting material layer at a side away from the electron transport layer, and an anode layer on the hole function layer; and/or the material of the luminescent material layer is a quantum dot, the quantum dot comprises a single-structure quantum dot selected from CdS, cdSe, cdTe, znS, znSe, znTe, hgS, hgSe, hgTe, pbS, pbSe, pbTe, cuInS, cdSeTe or a core-shell-structure quantum dot, the core of the core-shell-structure quantum dot comprises at least one of CdSe, cdS, cdTe, cdSe, cdSeTe, cdSnZnS, cdSeZnSe, pbSe, znTe, hgSe, hgTe, gaN, gaP, gaAs, inP, inAs, inP, inGaP, inGaN, the core-shell of the quantum dot is selected from ZnSe, znS, and at least one of the first metal elements in the ZnSe shell is selected from ZnSe, znSeS, and the first metal elements are any one of the first metal elements.

The embodiment of the invention also provides a manufacturing method of the light-emitting device, which comprises the following steps:

forming a ZnO film layer, a luminescent material film layer and a single precursor source film layer positioned between the luminescent material film layer and the ZnO film layer on a substrate to form a first substrate, wherein the single precursor source film layer comprises a single precursor source;

annealing the first substrate to form a sulfur-containing ZnO layer;

wherein the single precursor source comprises a single sulfur precursor or/and a zinc sulfur precursor.

In one embodiment, the single precursor source is selected from at least one of zinc N, N-diethyldithiocarbamate, zinc ethylxanthate, zinc isopropylxanthate, and zinc butylxanthate.

In an embodiment, the annealing the first substrate includes:

heating the first substrate to a first temperature and preserving heat for a first time;

cooling the first substrate to room temperature;

wherein the first temperature is 60 ℃ to 150 ℃ and the first time is 10 minutes to 60 minutes.

In one embodiment, the step of cooling the first substrate to room temperature includes:

sequentially carrying out a second cooling rate and a third cooling rate, and cooling the first substrate to room temperature;

wherein the second cooling rate is greater than the third cooling rate.

The embodiment of the invention also provides a display panel, which comprises any one of the light-emitting devices and the array substrate.

In one embodiment, the light emitting material layer includes a red light emitting unit, a green light emitting unit and a blue light emitting unit, and the sulfur-containing ZnO layer includes a red sulfur-containing ZnO unit corresponding to the red light emitting unit, a green sulfur-containing ZnO unit corresponding to the green light emitting unit and a blue sulfur-containing ZnO unit corresponding to the blue light emitting unit; wherein the thickness of the red sulfur-containing ZnO unit is greater than that of the green sulfur-containing ZnO unit, and the thickness of the green sulfur-containing ZnO unit is greater than that of the blue sulfur-containing ZnO unit.

According to the embodiment of the invention, the sulfur element on the sulfur-containing ZnO layer is combined with the first metal element on the surface of the luminescent material layer to form the coordinate bond, so that a new electron transmission path is formed, the interface potential barrier is reduced, the electron transmission rate from the electron transmission layer to the luminescent material layer is accelerated, and the photoelectric property and the stability of the luminescent device are favorably improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a first structure of a light-emitting device provided by an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a second structure of a light-emitting device provided by an embodiment of the present invention;

fig. 3 is a flowchart illustrating steps of a method for fabricating a light emitting device according to an embodiment of the present invention;

fig. 4 is a first schematic flow chart of a method for manufacturing a light-emitting device according to an embodiment of the present invention;

fig. 5 is a second schematic flow chart of a method for manufacturing a light-emitting device according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a first structure of a display panel according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a second structure of a display panel according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention. Furthermore, it should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, and are not intended to limit the present invention. In the present invention, unless otherwise specified, the use of directional terms such as "upper" and "lower" generally means upper and lower in the actual use or operation of the device, particularly in the orientation of the figures of the drawings; while "inner" and "outer" are with respect to the outline of the device.

In recent years, the inorganic nano-particle zinc oxide film serving as an electron transmission layer of a quantum dot light-emitting diode device can provide a better display color gamut and a longer light-emitting life, and has incomparable advantages of the traditional organic material, however, the interface barrier between the zinc oxide film and the quantum dot light-emitting diode device is higher, the electron transmission rate from the electron transmission layer to a light-emitting material layer is lower, and the working efficiency of quantum dots is lower.

Referring to fig. 1 and fig. 2, an embodiment of the invention provides a light emitting device 100, including a light emitting material layer 340 and an electron transport layer 350 disposed on the light emitting material layer 340;

wherein the light-emitting material layer 340 comprises a first metal element, the electron transport layer 350 comprises a sulfur-containing ZnO layer 351, and coordination bonds are connected between at least part of sulfur in the sulfur-containing ZnO layer 351 and the first metal element.

According to the embodiment of the invention, the sulfur element on the sulfur-containing ZnO layer is combined with the first metal element on the surface of the luminescent material layer to form the coordination bond, so that a new electron transmission path is formed, the interface barrier is reduced, the electron transmission rate from the electron transmission layer to the luminescent material layer is accelerated, and the photoelectric property and the stability of the luminescent device are favorably improved.

The technical solution of the present invention will now be described with reference to specific embodiments.

The light emitting device 100 includes a light emitting device layer including a light emitting material layer 340 and an electron transport layer 350 on the light emitting material layer 340;

the light emitting material layer 340 includes a first metal element, the electron transport layer 350 includes a sulfur-containing ZnO layer 351, and at least a portion of the sulfur element in the sulfur-containing ZnO layer 351 is connected to the first metal element by a coordination bond, specifically referring to fig. 1, wherein, for the bonding type, a dotted line represents a coordination bond, a solid line represents a covalent bond, and the first metal element in the light emitting material layer 340 is represented by "M". The sulfur element on the sulfur-containing ZnO layer is combined with the metal element on the surface of the luminescent material layer 340 to form a new electron transport path, thereby reducing the interface barrier and accelerating the electron transport rate from the electron transport layer 350 to the luminescent material layer 340.

In this embodiment, the sulfur-containing ZnO layer 351 is a zinc oxide-zinc sulfide cascade product, which includes not only zinc oxide and zinc sulfide, but also a coordination bond between sulfur in the zinc sulfide and a metal element in the light-emitting material layer 340.

In this embodiment, a covalent bond is connected between the sulfur element in the sulfur-containing ZnO layer 351 and the zinc element in the sulfur-containing ZnO layer 351, specifically refer to fig. 1.ZnS is also an n-type semiconductor with a wide direct band gap, with S atoms on the surface of the zinc oxide-sulfide and metal ions in the outermost layer of the quantum dots, e.g. Zn ²⁺ Strong coordination can be formed between the ions, a fine electron transfer path can be formed, and the injection of charges into the luminescent material layer 340 having quantum dots can be accelerated. In the sulfur-containing ZnO layer 351, covalent bonds may be formed between sulfur and zinc, a new electron transport path may be formed,the electron transfer rate in the cascade layer is enhanced, and the luminous efficiency is improved.

In the present embodiment, the electron transport layer 350 further includes a ZnS layer 353 located between the sulfur-containing ZnO layer 351 and the light-emitting material layer 340, specifically referring to fig. 2. The surface of a general resistance transmission layer formed by zinc oxide nanoparticles is connected with hydroxyl, but the surface of the resistance transmission layer is caused to present Lewis base characteristics by the hydroxyl, and in a quantum dot light-emitting diode device, a severe quenching effect can be generated on quantum dots of an adjacent light-emitting material layer 340, so that the photoelectric performance of the device is reduced. The ZnS layer 353 can serve as a passivation intermediate layer to reduce the quenching effect of the electron transport layer 350 on the interface of the light emitting material layer 340, and ZnS is also an n-type semiconductor with a wide direct band gap, and can also improve the overall stability of the light emitting device 100.

In this embodiment, in the electron transport layer 350 and/or the sulfur-containing ZnO layer 351, the molar ratio between sulfur and oxygen is 1. The introduction of sulfur element can construct a new electron transport channel, but excessive sulfur element also affects the transport stability and the lifetime of the electron transport layer 350, and by limiting the molar ratio of sulfur element to oxygen element, the relationship between the transport efficiency and the transport stability and the lifetime can be balanced, thereby improving the overall cost performance of the light emitting device 100.

In this embodiment, the content of the sulfur element in the sulfur-containing ZnO layer 351 is gradually decreased in a direction away from the luminescent material layer 340. In the manufacturing process, different annealing processes, for example, a slow-to-fast cooling process, may be used to enable the sulfur element content in the sulfur-containing ZnO layer 351 to achieve an effect of gradually decreasing the sulfur element content in a direction away from the luminescent material layer 340, and such content change may reduce an interface barrier, accelerate an electron transfer rate from the electron transfer layer 350 to the luminescent material layer 340, prolong a service life of the electron transfer layer 350, and improve a transfer stability of the electron transfer layer 350.

In this embodiment, the thickness of the electron transport layer 350 is 30 nm to 80 nm, the thickness of the sulfur-containing ZnO layer 351 is 30 nm to 80 nm, and the thickness of the ZnS layer 353 is 10 nm to 20 nm. By controlling the thickness of the ZnS layer 353, the quenching effect of the electron transport layer 350 on the interface of the light emitting material layer 340 can be reduced, the service life and the transmission stability of the light emitting device 100 can be improved, and by controlling the thickness of the sulfur-containing ZnO layer 351, the electron transport rate, the service life and the transmission stability of the light emitting device 100 can be improved, and meanwhile, the electron transport path can be shortened, and the light emission delay can be reduced.

In this embodiment, the roughness of the sulfur-containing ZnO layer 351 and the ZnS layer 353 is less than 1nm, so that the flatness of the film layer can be ensured, and the electronic transmission is facilitated.

In this embodiment, the material of the light emitting material layer 340 may be quantum dots, and the quantum dots may include at least one of single-structure quantum dots or composite-structure quantum dots in groups II-VI, III-V, IV-VI, VI-VI, viii-VI, I-III-VI, II-IV-VI, and II-IV-V of the periodic table. The material of the luminescent material layer is quantum dots, the quantum dots comprise single-structure quantum dots or core-shell structure quantum dots in II-VI groups, III-V groups, IV-VI groups, VIII-VI groups, I-III-VI groups, II-IV-VI groups and II-IV-V groups of the periodic table, the I groups and the II groups are sub-groups, the rest groups can be main groups or sub-groups, the single-structure quantum dots are selected from CdS, cdSe, cdTe, znSe, znTe, hgS, hgSe, hgTe, pbS, pbSe, pbTe, cuInS and CdSeTe, the core of the single-structure quantum dots comprises any one of CdSe, cdS, cdTe, cdSe, cdSeCdSe, znS, cdSeS, pbTe, hgS, hgSe, hgTe, gaN, eS, gaP, gaAs, inAs, inGaP, inGaN and at least one of ZnS and ZnS in the shell structure is selected from any one of the first metal elements and the core-shell structure quantum dots are selected from the first metal elements.

In this embodiment, the first metal element may be a metal element including at least three electrons in an outermost electron orbit, and the at least three outermost electrons make the property of the first metal element not too reactive, and more easily form coordinate bonds with at least part of sulfur elements in the sulfur-containing ZnO layer 351, so as to form a new electron transport path, thereby reducing an interface barrier and accelerating an electron transport rate from the electron transport layer 350 to the light emitting material layer 340.

In this embodiment, the light emitting device 100 may be an upright device structure or an inverted device structure.

In this embodiment, the light emitting device layers include an anode layer 310, a hole injection layer 320 on the anode layer 310, a hole transport layer 330 on the hole injection layer 320, a light emitting material layer 340 on the hole transport layer 330, an electron transport layer 350 on the light emitting material layer 340, and a cathode layer 360 on the electron transport layer 350.

In this embodiment, the light emitting device layer further includes an electron injection layer between the electron transport layer 350 and the cathode layer 360.

In this embodiment, the anode layer 310 may include any one or more of indium tin oxide, fluorine-doped tin oxide, indium zinc oxide, graphene, and carbon nanotubes; the material of the hole injection layer 320 may include PEDOT: any one or more of PSS, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide and copper oxide; the material of the hole transport layer 330 may include any one or more of PVK, poly-TPD, CBP, TCTA, and TFB; the material of the light emitting material layer 340 may include any one or more of nanocrystals of II-VI semiconductors, nanocrystals of III-V semiconductors, II-V compounds, III-VI compounds, IV-VI compounds, I-III-VI compounds, II-IV-VI compounds, group IV simple substances; the material of the cathode layer 360 may include any one or more of indium tin oxide, al, ca, ba, ag.

In this embodiment, the electron transport layer 350 further includes a ZnO layer 352 located on a side of the sulfur-containing ZnO layer 351 away from the ZnS layer 353, the material of the ZnO layer 352 may include n-type ZnO, and the ZnO layer 352 or/and the sulfur-containing ZnO layer 351 may further include a dopant, where the dopant may be any one or more of Al, ga, zr, mg, and Li.

Referring to fig. 3, an embodiment of the invention further provides a manufacturing method of the light emitting device 100, including:

s100, forming a ZnO film layer 3521, a luminescent material film layer 341, and a single precursor source film layer 3511 located between the luminescent material film layer 341 and the ZnO film layer 3521 on a substrate 110 to form a first substrate 101, where the single precursor source film layer 3511 includes a single precursor source and a solvent;

s200, annealing the first substrate 101 to form a sulfur-containing ZnO layer 351;

The method for manufacturing the light emitting device 100 includes:

s100, forming a ZnO film layer 3521, a luminescent material film layer 341, and a single precursor source film layer 3511 located between the luminescent material film layer 341 and the ZnO film layer 3521 on the substrate 110 to form the first substrate 101, where the single precursor source film layer 3511 includes a single precursor source and a solvent, which is described in detail with reference to fig. 4 and 5.

In this embodiment, the single precursor source is at least one selected from zinc N, N-diethyldithiocarbamate, zinc ethylxanthate, zinc isopropylxanthate, and zinc butylxanthate.

For example, the single precursor source is only zinc N, N-diethyldithiocarbamate, or for example, the single precursor source is a mixed solution of zinc N, N-diethyldithiocarbamate and zinc ethylxanthate, which may be selected according to actual needs, and is not limited herein.

In this embodiment, the concentration of the single precursor source solution film layer is 0.1mol/L to 0.5mol/L.

In this embodiment, the ZnO film 3521 may include an organic solution containing zinc and oxygen, such as an ethanol solution of ZnO, an ethanol solution of ZnMgO, and Zn (OH) ₂ Ethanol solution, etc., without limitation.

In this embodiment, the luminescent material film 341 includes a quantum dot material and may further include a quantum dot solvent, which is beneficial to inkjet printing or coating, and after the printing or coating is completed, the solvent in the luminescent material film 341 is volatile and can be heated or vacuum-removed.

In this embodiment, the light emitting device 100 may be an upright device structure or an inverted device structure, that is, the sequence of forming the film layers in the light emitting device 100, for the upright device structure in the embodiment of the present invention, the single precursor source film layer 3511 is formed on the light emitting material film layer 341 formed on the substrate 110, and then the ZnO film layer 3521 is formed on the single precursor source film layer 3511, where the substrate 110 may be a hole transport layer 330, specifically refer to fig. 4; for the inverted device structure in the embodiment of the present invention, the ZnO film layer 3521 is formed on the substrate 110, a single precursor source film layer 3511 is formed on the ZnO film layer 3521, and a light emitting material film layer 341 is formed on the single precursor source film layer 3511, which is specifically shown in fig. 5.

In this embodiment, for an upright device structure or/and an inverted device structure, the forming step of the single precursor source film layer 3511 includes: coating or spin-coating a single precursor source solution film layer; and removing the solvent in the single precursor source solution film layer. The single precursor source solution film layer comprises the single precursor source and a solvent, wherein the solvent comprises any one of the following components: benzene, toluene, chloroform, carbon tetrachloride and ethanol. And evaporating and removing the solvent in the single precursor source solution film layer to reduce the fluidity of the single precursor source solution film layer and improve the film layer precision in the manufacturing of the light-emitting device 100.

In this embodiment, for the ZnO film layer 3521, the light-emitting material film 341, and the single precursor source film 3511 in the first substrate 101, after forming the respective films, annealing may be performed, for example, forming the ZnO film layer 3521 on the substrate 110, and performing a first annealing process; forming a single precursor source film layer 3511 on the ZnO film layer 3521, and performing a second annealing process; finally, a luminescent material film 341 is formed on the single precursor source film 3511; and a step S200 of annealing the entire first substrate 101. And the annealing is carried out step by step respectively, so that the solvent can be removed and the pre-curing is carried out, the manufacturing position precision and the refinement of the film layer are improved, and the working performance of the film layer can be improved.

S200, annealing treatment is carried out on the first substrate 101, so that a sulfur-containing ZnO layer 351 is formed.

In this embodiment, step S200 includes:

s210, heating the first substrate 101 to a first temperature and keeping the temperature for a first time.

S220, cooling the first substrate 101 to room temperature to form a sulfur-containing ZnO layer 351.

In this embodiment, after the first substrate 101 is cooled to room temperature, the light emitting material layer 341 forms the light emitting material layer 340, and the ZnO layer 3521 and the single precursor source layer 3511 form the sulfur-containing ZnO layer 351, wherein, according to different annealing processes (for example, increasing or decreasing the annealing time), a ZnS layer 353 and a ZnO layer 352 may be further formed on two sides of the sulfur-containing ZnO layer 351, as shown in fig. 2.

In this embodiment, the first temperature is 60 ℃ to 150 ℃, and the first time is 10 minutes to 60 minutes.

In this embodiment, step S220 includes:

s221a, cooling the first substrate 101 to room temperature at a first cooling rate.

In this embodiment, the first cooling rate is 2 ℃/min to 10 ℃/min. The constant-speed cooling is adopted, so that the uniform formation of the sulfur-containing ZnO layer 351 can be ensured.

In this embodiment, step S220 includes:

and S221b, sequentially carrying out a second cooling rate and a third cooling rate, and cooling the first substrate 101 to room temperature.

In this embodiment, the second cooling rate and the third cooling rate are sequentially experienced, that is, the temperature is subjected to program cooling, and the second cooling rate is different from the third cooling rate.

In this embodiment, the second temperature reduction rate is greater than the third temperature reduction rate, that is, the sulfur element content is gradually reduced in a first-speed-last-slow temperature reduction manner, and the content change can reduce an interface barrier, increase an electron transmission rate from the electron transmission layer 350 to the light emitting material layer 340, prolong a service life of the electron transmission layer 350, and improve a transmission stability of the electron transmission layer 350, while reducing the interface barrier.

In this embodiment, the formation of the sulfur-containing ZnO layer 351 is mainly performed in step S210, and the formation of the sulfur-containing ZnO layer 351 may be further refined by performing temperature-changing and heat-preserving within the heat-preserving range of the first temperature, for example, by slowly raising the temperature from 60 ℃ to 150 ℃ within 60 minutes, and then reducing the temperature.

In the embodiment, an upright device structure is adopted, 50ul of 0.2mmol/ml zinc N, N-diethyldithiocarbamate toluene solution is removed in vacuum at normal temperature on a red quantum dot light-emitting layer by means of spin coating, then a toluene solvent is removed at normal temperature, an electron transport layer ZnO is deposited, the manufactured device is subjected to heat preservation annealing for 20min on a hot plate at 120 ℃, the zinc N, N-diethyldithiocarbamate is decomposed to form ZnS, a cascaded sulfur-containing ZnO layer is formed with ZnO, the ZnO and quantum dot interface is separated by the formed ZnS, and the phenomenon that the surface hydroxyl of the zinc oxide with Lewis base property quenches the quantum dot is avoided; meanwhile, in the process, the sulfur atoms in contact with the quantum dot interface generate coordination with zinc atoms on the surface of the quantum dot to form a fine electron transfer path, which is beneficial to effectively injecting electrons into the quantum dot light-emitting layer. Due to elimination of quenching influence of ZnO on quantum dots of the light-emitting layer and improvement of electron transfer efficiency, the light-emitting material layer 340 with the quantum dots has the light-emitting wavelength =625nm, the FWHM (full width at half maximum) =22nm, the External Quantum Efficiency (EQE) of the device is as high as 19%, and the T95@1000nit =2200h with good stability is obtained; the result of the test of the comparative device without the cascade electron transport layer 350 is that the EQE is 13%, and the test result is that the t95@1000nit =1300h. Wherein, T95@1000nit represents that the continuous brightness test is carried out from 1000nit brightness, and when the brightness is reduced for only 95% of the brightness, the service life of the light-emitting brightness can be represented.

In this embodiment, an inverted device structure is adopted, znO is deposited on ITO, 30ul 0.4mmol/ml zinc ethyl xanthate benzene solution is spin-coated on a ZnO film at a rotation speed of 3000rpm, and a benzene solvent is removed in vacuum at normal temperature to obtain a dried film, then green quantum dots are deposited on the film, and the fabricated device is subjected to thermal insulation annealing at a hot plate of 90 ℃ for 30min, thereby obtaining the luminescent wavelength =535nm, fwhm =24nm, eqe (Max) =18.5%, and tj95 @1000nit =5300h of the luminescent material layer 340 with the quantum dots; in contrast, for a device in which no cascade layer is formed, EQE (Max) =11%, and tj @1000nit =1800h.

In this embodiment, the solvent in the single precursor source solution film layer may also be removed in the annealing process.

In this example, the production parameters of the experimental product 1 are as follows: and (3) coating a hole injection layer PEDOT on the ITO of the anode layer: PSS material, then annealing for 15min at 100 ℃; then forming a TFB hole transport layer 330 on the hole injection layer 320, and annealing at 100 ℃ for 15min; forming a light emitting layer of CdZnSe/ZnSe/ZnS red quantum dots on the hole transport layer 330; 50ul of a 0.2mmol/ml zinc N, N-diethyldithiocarbamate solution in toluene; preparing an ethanol solution of ZnO on the luminescent layer, and performing thermal annealing on a hot plate at 120 ℃ for 20min to obtain a sulfur-containing ZnO layer 351; and finally, evaporating an Ag cathode electrode layer, and packaging, wherein the CdZnSe/ZnSe/ZnS represents three-layer lamination.

In this example, the production parameters of comparative example 1 were the same as those of experiment 1 except that "50. Mu.l of a 0.2mmol/ml zinc N, N-diethyldithiocarbamate toluene solution" was removed.

In this example, the production parameters of the experimental article 2 are as follows: and (3) coating a hole injection layer PEDOT on the ITO of the anode layer: PSS material, then annealing for 15min at 100 ℃; then forming a TFB hole transport layer on the hole injection layer 320, and annealing at 100 ℃ for 15min; forming a light-emitting layer of CdZnSeS/ZnS green quantum dots on the hole transport layer 330; 30ul of 0.3mmol/ml zinc ethylxanthate benzene solution; preparing an ethanol solution of ZnMgO containing 5% of magnesium on the luminescent layer, and carrying out thermal annealing on a hot plate at 90 ℃ for 30min to obtain a sulfur-containing ZnO layer; and finally, performing encapsulation by evaporating an Ag cathode electrode layer, wherein CdZnSeS/ZnS represents two-layer lamination.

In this example, the production parameters of comparative example 2 were the same as those of Experimental example 2 except that "30. Mu.l of a 0.3mmol/ml zinc ethylxanthate benzene solution" was removed.

Referring to fig. 6, an embodiment of the invention further provides a display panel 10 including any one of the light emitting devices 100 and the array substrate 200.

For a specific structure of the light emitting device 100, refer to any one of the above embodiments of the light emitting device 100 and fig. 1 to 2.

In this embodiment, the light emitting material layer 340 of the light emitting device 100 includes a red light emitting unit, a green light emitting unit, and a blue light emitting unit, and the sulfur-containing ZnO layer 351 includes a red sulfur-containing ZnO unit corresponding to the red light emitting unit, a green sulfur-containing ZnO unit corresponding to the green light emitting unit, and a blue sulfur-containing ZnO unit corresponding to the blue light emitting unit; the thickness of the red sulfur-containing ZnO unit is greater than that of the green sulfur-containing ZnO unit, and the thickness of the green sulfur-containing ZnO unit is greater than that of the blue sulfur-containing ZnO unit, as shown in fig. 7. According to the emission wavelength and the transmission efficiency of different colors, the electron transmission efficiency of different emission colors is improved by changing the thicknesses of different sulfur-containing ZnO units, so that the emission efficiency of different colors is uniform, and the uniformity is favorably displayed.

In this embodiment, the red sulfur-containing ZnO unit, the green sulfur-containing ZnO unit, and the blue sulfur-containing ZnO unit all include the dopant, the content of the dopant in the red sulfur-containing ZnO unit is less than the content of the dopant in the green sulfur-containing ZnO unit, and the content of the dopant in the green sulfur-containing ZnO unit is less than the content of the dopant in the blue sulfur-containing ZnO unit, and by controlling the content of the dopant, the electron transmission rates of different emission colors can be significantly increased, so that the emission efficiencies of different colors are uniform, and the display uniformity is balanced.

The display panel 10 performs parameter characterization by using the light emitting device 100, and the result corresponds to the following:

the characterization parameters of the test article 1 are as follows: emission wavelength =625nm, fwhm =21nm, eqe =19%, and tj @1000nit =2200h.

The characterization parameters of comparative 1 are as follows: emission wavelength =625nm, fwhm =21nm, eqe =13%, tj 95@1000nit =1300h.

The characterization parameters of experiment 2 are as follows: luminescence wavelength =532nm, fwhm =23nm, eqe =17.8%, tj 95@1000nit =5600h.

The characterization parameters of comparative 2 were as follows: luminous wavelength =532nm, fwhm =23nm, eqe =13.8%, and tj 95@1000nit =2700h.

It can be seen that, compared with the comparative product 1, the eqe of the experimental product 1 is significantly improved, and the service life of the experimental product 2 is significantly prolonged, which indicates that the introduction of the sulfur-containing ZnO layer 351 can accelerate the electron transfer rate from the electron transfer layer 350 to the light-emitting material layer 340, thereby facilitating the improvement of the photoelectric property and stability of the display panel 10, and prolonging the service life of the display panel 10.

The life test adopts a 128-channel life test system customized by Guangzhou New View company. The system is constructed by driving a QLED by a constant voltage and constant current source and testing the change of voltage or current; a photodiode detector and test system to test the variation of brightness (photocurrent) of the QLED; the luminance meter test calibrates the luminance (photocurrent) of the QLED.

The embodiment of the invention discloses a light-emitting device, a manufacturing method thereof and a display panel; the light-emitting device comprises a light-emitting material layer and an electron transmission layer positioned on the light-emitting material layer; the electron transport layer comprises a sulfur-containing ZnO layer, and a coordination bond is connected between sulfur in the sulfur-containing ZnO layer and the first metal element; according to the embodiment of the invention, the sulfur element on the sulfur-containing ZnO layer is combined with the first metal element on the surface of the luminescent material layer to form the coordinate bond, so that a new electron transmission path is formed, the interface potential barrier is reduced, the electron transmission rate from the electron transmission layer to the luminescent material layer is accelerated, and the photoelectric property and the stability of the luminescent device are favorably improved.

The light emitting device, the manufacturing method thereof, and the display panel provided by the embodiments of the present invention are described in detail above, and the principles and embodiments of the present invention are explained herein by applying specific examples, and the description of the above embodiments is only used to help understanding the method and the core concept of the present invention; meanwhile, for those skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. A light-emitting device is characterized by comprising a light-emitting material layer and an electron transport layer positioned on the light-emitting material layer;

2. The light-emitting device according to claim 1, wherein a covalent bond is connected between sulfur in the sulfur-containing ZnO layer and zinc in the sulfur-containing ZnO layer.

3. The light-emitting device according to claim 2, wherein the electron transport layer further comprises a ZnS layer between the sulfur-containing ZnO layer and the light-emitting material layer.

4. The light-emitting device according to claim 1, wherein the sulfur element content in the sulfur-containing ZnO layer gradually decreases in a direction away from the light-emitting material layer.

5. The light-emitting device according to claim 1, wherein in the sulfur-containing ZnO layer, a molar ratio of sulfur element to oxygen element is 1.

6. The light-emitting device according to claim 1, further comprising a cathode layer on the electron-transporting layer on a side away from the light-emitting material layer, a hole-functional layer on the light-emitting material layer on a side away from the electron-transporting layer, and an anode layer on the hole-functional layer; and/or

The material of the luminescent material layer is quantum dots, the quantum dots comprise single-structure quantum dots or core-shell structure quantum dots in II-VI groups, III-V groups, IV-VI groups, VIII-VI groups, I-III-VI groups, II-IV-VI groups and II-IV-V groups of the periodic table, the single-structure quantum dots are selected from CdS, cdSe, cdTe, znS, znSe, znTe, hgS, hgSe, hgTe, pbS, pbSe, pbTe, cuInS and CdSeTe, the core of the core-shell structure quantum dots comprises at least one of CdSe, cdS, cdTe, cdSeTe, cdSZnS, pbSe, znTe, cdSeS, pbTe, hgS, hgSe, hgTe, gaP, gaAs, gaN, inP, inZnP, inQuantum and InGaN, the core-shell structure quantum dots are selected from GaP, znSe and the shell is selected from at least one metal element of the first metal eSe.

7. A method of fabricating a light emitting device, comprising:

annealing the first substrate to form a sulfur-containing ZnO layer;

8. The method for manufacturing a light-emitting device according to claim 7, wherein the single precursor source is at least one selected from the group consisting of zinc N, N-diethyldithiocarbamate, zinc ethylxanthate, zinc isopropylxanthate, and zinc butylxanthate.

9. The method for manufacturing a light-emitting device according to claim 7, wherein the annealing the first substrate comprises:

cooling the first substrate to room temperature;

10. The method of claim 7, wherein the step of cooling the first substrate to room temperature comprises:

wherein the second cooling rate is greater than the third cooling rate.

11. A display panel comprising the light emitting device according to any one of claims 1 to 6 and an array substrate.

12. The display panel according to claim 11, wherein the light-emitting material layer comprises a red light-emitting unit, a green light-emitting unit, and a blue light-emitting unit, and wherein the sulfur-containing ZnO layer comprises a red sulfur-containing ZnO unit corresponding to the red light-emitting unit, a green sulfur-containing ZnO unit corresponding to the green light-emitting unit, and a blue sulfur-containing ZnO unit corresponding to the blue light-emitting unit;

wherein the thickness of the red sulfur-containing ZnO unit is greater than that of the green sulfur-containing ZnO unit, and the thickness of the green sulfur-containing ZnO unit is greater than that of the blue sulfur-containing ZnO unit.