Quantum dot light-emitting diode and display apparatus thereof

Abstract

A quantum dot light-emitting diode and a display apparatus comprising the quantum dot light-emitting diode are provided. The quantum dot light-emitting diode comprises an anode, a hole injecting layer, a hole transporting layer, a quantum dot light-emitting layer, an electron transporting layer and a cathode from bottom to top, wherein the materials of the quantum dot light-emitting layer contain quantum dots and CuSCN nano-particles. By blending quantum dots and CuSCN nano-particles into a membrane to prepare a quantum dot light-emitting layer, a hole trap state on the surface of the quantum dots is passivated, and the transporting effect of a hole is improved, so that the injection of holes in the quantum dot light-emitting diode and that of electrons achieve balance, and thus the light-emitting efficiency and stability are improved.

Claims

1. A quantum dot (QD) light-emitting diode, wherein comprising an anode, a cathode, and a QD light emitting layer arranged between the anode and the cathode; wherein a material of the QD light-emitting layer comprises a plurality of QDs and a plurality of cuprous thiocyanate (CuSCN) nanoparticles, and a mass ratio between the QDs and the CuSCN nanoparticles is in a range of 0.00120:1.

2. The QD light-emitting diode according to claim 1, wherein further comprising a holes injection layer arranged between the anode and the QD light emitting layer, a holes transport layer arranged between the holes injection layer and the QD light-emitting layer, and an electrons transport layer arranged between the cathode and the QD light-emitting layer, the holes transport layer overlays the QD light-emitting layer.

3. The QD light-emitting diode according to claim 1, wherein a thickness of the QD light-emitting layer is 10100 nm.

4. The QD light-emitting diode according to claim 1, wherein a size range of the CuSCN nanoparticles is 0.550 nm.

5. A display apparatus, wherein comprising the QD light-emitting diode according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a diagram on a transport mechanism of a carrier in the QD light-emitting layer in a conventional QD light-emitting diode.

(2) FIG. 2 illustrates a schematic diagram on a preferred embodiment of the QD light-emitting diode disclosed in the present disclosure.

(3) FIG. 3 illustrates a diagram on a transport mechanism of a carrier in the QD light-emitting layer of the QD light-emitting diode disclosed in the present disclosure.

(4) FIG. 4 illustrates a flow chart on a preferred embodiment of the preparation method of the QD light-emitting diode disclosed in the present disclosure.

(5) FIG. 5 illustrates a schematic diagram on an energy level of the QD light-emitting diode in the example 1 of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

(6) The present disclosure provides a QD light-emitting diode and a preparation method therefor, and a light-emitting module and a display apparatus, in order to make the purpose, technical solution and the advantages of the present disclosure clearer and more explicit, further detailed descriptions of the present disclosure are stated here, referencing to the attached drawings and some preferred embodiments of the present disclosure. It should be understood that the detailed embodiments of the disclosure described here are used to explain the present disclosure only, instead of limiting the present disclosure.

(7) Referencing to FIG. 2, which illustrates a schematic diagram on a preferred embodiment of the QD light-emitting diode disclosed in the present embodiment, shown as the figure, the QD light-emitting diode comprises sequentially from bottom up, an anode 1, a holes injection layer 2, a holes transport layer 3, a QD light-emitting layer 4, an electron transport layer 5 and a cathode 6; wherein a material of the QD light-emitting layer 4 comprises a plurality of QDs 41 and a plurality of CuSCN nanoparticles 42.

(8) The present embodiment forms a membrane from a mixture containing a plurality of QDs and a plurality of CuSCN nanoparticles, to prepare a QD light-emitting layer, because the CuSCN nanoparticles used has not only an excellent holes transport ability, but also a rich source and a lower cost. In addition, as shown in FIG. 3, wherein 20 is a holes transport layer, 21 is a plurality of CuSCN nanoparticles, 22 is a plurality of QDs, and 23 is an electrons transport layer, through blending the CuSCN nanoparticles 21 and the QDs 22, and forming a membrane, a plurality of tiny CuSCN nanoparticles 21 are filling in a plurality of gaps between the QDs 22, acting as an additive for a holes transport, which on one hand, is able to passivate a hole trap state on a surface of the QDs 22, and on the other hand, is acting as a bridge for the holes transport in the QD light-emitting layer, improving a holes transport effect, and overcomes effectively a plurality of problems including a carrier (a hole and an electron) injection imbalance causing a device performance degradation in a QLED device.

(9) The present embodiment dissolves the QDs and the CuSCN nanoparticles in a solvent, and forms a mixture, before depositing the mixture and forming a QD light-emitting layer containing a plurality of CuSCN nanoparticles. Wherein a mass ratio between the QDs and the CuSCN nanoparticles is 0.00120:1.

(10) Preferably, a thickness of the QD light-emitting layer described in the present embodiment is 10100 nm, for example, the thickness may be 50 nm, 80 nm or 100 nm.

(11) Preferably, a size range of the CuSCN nanoparticles described in the present embodiment is 0.550 nm, for example, the size range may be 5 nm, 10 nm or 30 nm.

(12) The CuSCN nanoparticles described in the present embodiment may be a doped or undoped CuSCN material. The CuSCN nanoparticles may be prepared by a chemical method or a physical method, wherein the chemical method includes but not limited to, a sol-gel method, a chemical bath deposition method, a chemical vapor deposition method, a hydrothermal method, a co-precipitation method, and an electrochemical deposition method; the physical method includes but not limited to, a thermal evaporation coating method, an electron beam evaporation coating method, a magnetron sputtering method, a multi-arc ion plating method, and an electrolysis method.

(13) The CuSCN nanoparticles embedding in the gaps between the QDs, on one hand, it is able to passivate the hole trap state on the surface of the QDs, and on the other hand, it is able to reduce an energy barrier of the holes injecting into the QDs, improving a transport efficiency of the holes, making an injection number in the QD light-emitting layer between the holes and the electrons get balanced, thus improving a light-emitting efficiency of the QLED device.

(14) Specifically, the QDs of the present embodiment may be, but not limited to, one or more of an II-V compound semiconductor, an III-V compound semiconductor, an IV-VI compound semiconductor and a core-shell structure thereof.

(15) Specifically, the anode of the present embodiment may be, but not limited to, one or more of indium doped tin oxide (ITO), fluorine doped tin oxide (FTO), antimony doped tin oxide (ATO), and aluminum doped zinc oxide (AZO).

(16) Specifically, the holes injection layer may be, but not limited to, one or more of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), CuPc (Copper(II) phthalocyanine), F4-TCNQ (2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane), HATCN (dipyrazino[2,34:2,3-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile), undoped transition metal oxide, doped transition metal oxide, metal sulfur group compound, doped metal sulfur group compound. Wherein, the transition metal oxide may be, but not limited to, MoO.sub.3, VO.sub.2, WO.sub.3, CrO.sub.3, CuO or a mixture thereof; the metal sulfur group compound may be, but not limited to, MoS.sub.2, MoSe.sub.2, WS.sub.2, WSe.sub.2, CuS or a mixture thereof.

(17) Specifically, the holes transport layer in the present embodiment may be selected from an organic material having a holes transport ability, and may be, but not limited to, poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB), polyvinyl carbazole (PVK), poly(N,N-bis(4-butylphenyl)-N,N-bis(phenyl)-benzidine) (poly-TPD), poly(9,9-dioctylfluorene-co-bis-N,N-phenyl-1,4-phenylenediamine) (PFB), 4,4,4-tris(carbazol-9-yl)-triphenylamine (TCTA), 4,4-bis(carbazol-9-yl)biphenyl (CBP), N,N-bis(3-methylphenyl)-N,N-bis(phenyl)-1,1-biphenyl-4,4-diamine(TPD), N, N-bis-(1-naphthalenyl)-N,N-bis(phenyl)-1,1-biphenyl-4,4-diamine(NPB), doped graphene, undoped graphene, C60 or a mixture thereof.

(18) Specifically, the holes transport layer in the present embodiment may further be selected from an inorganic material having the holes transport ability, and may be, but not limited to, NiO, WO.sub.3, MoO.sub.3, CuO, VO.sub.2, CrO.sub.3, MoS.sub.2, MoSe.sub.2, WS.sub.2, WSe.sub.2, CuS, or a mixture thereof.

(19) Specifically, a material of the electrons transport layer in the present embodiment may be one or more of n-type ZnO, TiO.sub.2, SnO.sub.2, Ta.sub.2O.sub.3, AlZnO, ZnSnO, InSnO, Alq.sub.3, Ca, Ba, CsF, LiF, CsCO.sub.3. Preferably, the electrons transport layer is n-type ZnO, an n-type TiO.sub.2.

(20) Specifically, a material of the cathode in the present embodiment may be, but not limited to, one or more of Al, Ag, Cu, Mo, Au, or an alloy thereof.

(21) The QD light-emitting diode of the positive structures described above in the present embodiment is not limited to the functional layers described above, and may further include an interface functional layer or an interface modification layer, which includes but not limited to, one or more of an electron blocking layer, a hole blocking layer, an electrode modification layer and an isolation protection layer.

(22) It should be noted that the mixture of the QDs and the CuSCN nanoparticles in the present embodiment is not limited to preparing a QD light-emitting diode having a positive structure, but also being able to prepare a QD light-emitting diode having an inverted structure. The QD light-emitting diode having the inverted structure is not limited to the functional layers described above, and may further include an interface functional layer or an interface modification layer, which comprises, but not limited to, one or more of the an electron blocking layer, a hole blocking layer, an electrode modification layer, and an isolate protection layer.

(23) The present embodiment further provides a light-emitting module, which comprises the QD light-emitting diode described above.

(24) The present embodiment further provides a display apparatus, which comprises the QD light-emitting diode described above, or the light-emitting module described above.

(25) Based on the QD light-emitting diode, the present embodiment further provides a flow chart on a preferred embodiment of a preparation method of the QD light-emitting diode disclosed in the present embodiment, shown as FIG. 4, comprising:

(26) step S100, prepare a holes injection layer on the anode;

(27) step S200, then prepare a holes transport layer on the holes injection layer;

(28) step S300, followed by preparing a QD light-emitting layer on the holes transport layer; wherein the QD light-emitting layer is prepared from a mixture of the QDs and the CuSCN nanoparticles;

(29) step S400: finally prepare an electrons transport layer on the QD light-emitting layer, and vapor deposit a cathode on the electrons transport layer before forming a QD light-emitting diode.

(30) Specifically, the step S300 of the present embodiment comprises: spin-coat a mixture of the QDs and the CuSCN nanoparticles on the holes transport layer to form a QD light-emitting layer containing the CuSCN nanoparticles.

(31) The present embodiment blends the QDs with the CuSCN nanoparticles, before forming a CuSCN-enhanced QD light-emitting layer by an evaporation method or a solution film formation method including a plurality of processes of a spin coating, an ink spraying, a blade coating or the like.

(32) The present embodiment dissolves the QDs and the CuSCN nanoparticles in a solvent to form a mixture, before depositing the mixture and forming a QD light-emitting layer containing the CuSCN nanoparticles. Wherein, a mass ratio of the QDs to the CuSCN nanoparticles is 0.00120:1. In the mixture, a concentration of the QDs is 1 to 50 mg/mL, a concentration of the CuSCN nanoparticles is 0.001 to 50 mg/mL. Preferably, in the mixture, a concentration of the QDs is 10-20 mg/mL, and a concentration of the CuSCN nanoparticles is 0.01-10 mg/mL. A solvent used in the mixture may be, but not limited to, one or more of an n-octane, an isooctane, a toluene, a benzene, a chlorobenzene, a xylene, a chloroform, an acetone, a cyclohexane, an n-hexane, an n-pentane, an isopentane, an n-butyl ether, an anisole, a phenethyl ether, an acetophenone, an aniline, a diphenyl ether, an N,N-dimethylformamide, an N-methylpyrrolidone, a dimethyl sulfoxide, a hexamethylphosphoramide.

(33) The preparation method of the functional layers described above of the present embodiment may be a chemical method or a physical method, wherein the physical method includes, but not limited to, a spin coating method, a spray coating method, a roll coating method, a typing method, a printing method, an inkjet method, a dip coating method, a thermal evaporation coating method, an electron beam evaporation coating method, a magnetron sputtering method, a multi-arc ion plating method; the chemical methods include, but not limited to, a chemical vapor deposition method, a successive ionic layer adsorption and reaction method, an anodization method, an electrolytic deposition method, a coprecipitation method.

(34) The preparation method disclosed in the present embodiment is simple, and may solve effectively a plurality of problems in the prior art of a poor film formation, a complicated structure, a high material cost and a difficult industrialization. In addition, the prepared device has an excellent performance, a good stability, and a long service life.

(35) A detailed description is listed herein, taking a preparation process of the QD light-emitting layer and a preparation process of the QLED device as examples.

EXAMPLE 1

(36) 1) Prepare a mixture of the CuSCN nanoparticles and the QDs: dissolve 10 mg CuSCN powder and 15 mg CdSe@ZnS QDs in 1 mL n-octane, mix well and form a uniform mixture.

(37) 2). A plurality of preparation steps of the QLED device is as follows: spin coat a layer of the PEDOT:PSS holes injection layer on the ITO substrate; spin coat a layer of the PVK holes transport layer on the PEDOT:PSS holes injection layer;

(38) 3). Spin-coat the mixture of the CuSCN nanoparticles and the QDs on the PVK holes transport layer, and form a QD light-emitting layer containing the CuSCN nanoparticles;

(39) 4). Followed by spin-coating a layer of the ZnO electrons transport layer on the QD light-emitting layer;

(40) 5). Finally, an Al cathode is evaporated on the ZnO electrons transport layer, to obtain the QD light-emitting diode, whose energy level structure is shown in FIG. 5.

EXAMPLE 2

(41) 1) Prepare a mixture of the CuSCN nanoparticles and the QDs: dissolve 5 mg CuSCN powder and 15 mg CdSe@ZnS QDs in 1 mL n-octane, mix well and form a uniform mixture.

(42) 2). A plurality of preparation steps of the QLED device is as follows: spin coat a layer of the PEDOT:PSS holes injection layer on the ITO substrate;

(43) spin coat a layer of the PVK holes transport layer on the PEDOT:PSS holes injection layer;

(44) 3). Spin-coat the mixture of the CuSCN nanoparticles and the QDs on the PVK holes transport layer, and form a QD light-emitting layer containing the CuSCN nanoparticles;

(45) 4). Followed by spin-coating a layer of the ZnO electrons transport layer on the QD light-emitting layer;

(46) 5). Finally, an Al cathode is evaporated on the ZnO electrons transport layer, to obtain the QD light-emitting diode.

EXAMPLE 3

(47) 1) Prepare a mixture of the CuSCN and the QDs: dissolve 0.1 mg CuSCN powder and 15 mg CdSe@CdS@ZnS QDs in 1 mL n-octane, mix well and form a uniform mixture.

(48) 2). A plurality of preparation steps of the QLED device is as follows: spin coat a layer of the PEDOT:PSS holes injection layer on the ITO substrate; spin coat a layer of the TFB holes transport layer on the PEDOT:PSS holes injection layer;

(49) 3). Spin-coat the mixture of the CuSCN nanoparticles and the QDs on the TFB holes transport layer, and form a QD light-emitting layer containing the CuSCN nanoparticles;

(50) 4). Followed by spin-coating a layer of the ZnO electrons transport layer on the QD light-emitting layer;

(51) 5). Finally, an Al cathode is evaporated on the ZnO electrons transport layer, to obtain the QD light-emitting diode.

EXAMPLE 4

(52) 1) Prepare a mixture of the CuSCN and the QDs: dissolve 0.05 mg CuSCN powder and 20 mg CdSe@CdS@ZnS QDs in 1 mL n-octane, mix well and form a uniform mixture.

(53) 2). A plurality of preparation steps of the QLED device is as follows: spin coat a layer of the PEDOT:PSS holes injection layer on the ITO substrate; spin coat a layer of the poly-TPD holes transport layer on the PEDOT:PSS holes injection layer;

(54) 3). Spin-coat the mixture of the CuSCN nanoparticles and the QDs on the poly-TPD holes transport layer, and form a QD light-emitting layer containing the CuSCN nanoparticles;

(55) 4). Followed by spin-coating a layer of the ZnO electrons transport layer on the QD light-emitting layer;

(56) 5). Finally, an Al cathode is evaporated on the ZnO electrons transport layer, to obtain the QD light-emitting diode.

(57) All above, the present disclosure provides a QD light-emitting diode and a preparation method therefor, and a light-emitting module and a display apparatus. The present disclosure blends the QDs and the CuSCN nanoparticles into a membrane to prepare the QD light-emitting layer, and passivates a hole trap state on a surface of the QDs, as well as improving a transport effect of the holes, making an injection of the holes and the electrons in the QLED achieve a balance, thus improving a light-emitting efficiency and a stability of the QLED.

(58) It should be understood that, the application of the present disclosure is not limited to the above examples listed. Ordinary technical personnel in this field can improve or change the applications according to the above descriptions, all of these improvements and transforms should belong to the scope of protection in the appended claims of the present disclosure.