TWI740209B - Quantum dot light-emitting diode and manufacturing method thereof - Google Patents

Abstract

The present invention discloses a quantum dot light-emitting diode (QLED) and a manufacturing method thereof. The QLED comprises a first electrode to be sequentially provided with an electron hole injection layer, an electron hole transporting layer, a quantum dot emissive layer, an electron transporting layer and a second electrode, wherein the electron hole transporting layer comprises a main material and a thermally activated delayed fluorescence material. The manufacturing method comprises the steps of sequentially coating the electron hole injection layer, the electron hole transporting layer, the quantum dot emissive layer and the electron transporting layer on the first electrode, and disposing the second electrode on the electron transporting layer. The electron hole transporting layer of the QLED comprises the thermally activated delayed fluorescence material which reduces driving voltage and improves brightness and luminous efficiency of the QLED.

Description

Quantum dot light-emitting diode and manufacturing method thereof

The present invention relates to a quantum dot light-emitting diode and a manufacturing method thereof. The thermally activated delayed fluorescent material is added to the hole transport layer, which can reduce the driving voltage of the quantum dot light-emitting diode and increase the quantum dot light-emitting diode Body brightness and luminous efficiency.

Quantum dot (Quantum dot) is a nanocrystalline semiconductor material composed of dozens of atoms. Its emission wavelength band is narrower than that of traditional organic dyes, and quantum dots of different compositions and sizes can be excited by the same light. Original excitation to emit light of different wavelengths. At present, quantum dots have been used in the preparation of screen displays. For example, photoluminescence quantum dots are installed in the backlight module of liquid crystal display (LCD) to obtain better backlight utilization. For example, electroluminescence quantum dots are used to prepare quantum dots to emit light. Diode (QLED); due to the narrow emission wavelength band of quantum dots, pure and high-quality red or green monochromatic light can be obtained, thereby improving the display efficiency.

The Republic of China Patent No. TW I661031(B) discloses an organic electroluminescence device and a preparation method thereof. The organic electroluminescence device includes a substrate, and an anode, a hole transport layer, a light-emitting layer, and a light-emitting layer are sequentially prepared on the substrate. The electron transport layer and the cathode, the light-emitting layer contains host materials, auxiliary materials and fluorescent dyes, the host material is a mixture of electron supply materials and electron acceptor materials, and the auxiliary material is a thermally activated delayed fluorescent material; also, Zhonghua Mingguo Patent In the light-emitting device of Patent No. TW I666299(B), a thermally activated delayed fluorescent material is also incorporated into the light-emitting layer. Generally, as a polymer luminescent material or fluorescent material, the internal quantum efficiency of the theoretical value is 25%, so its energy conversion efficiency is limited. Therefore, how to improve the luminous brightness and luminous efficiency of quantum dot light-emitting devices has always been an important research and development in this technical field. Target.

Nowadays, in view of the shortcomings of the existing quantum dot light-emitting diodes, the inventor is based on the tireless spirit, and with the help of his rich professional knowledge and years of practical experience, he has made improvements and researched accordingly. Created the present invention.

The present invention relates to a quantum dot light-emitting diode and a manufacturing method thereof. A thermally activated delayed fluorescence material (thermally activated delayed fluorescence) is added to a hole transport layer, which can effectively improve the brightness of the quantum dot light-emitting diode and Luminous efficiency.

The quantum dot light-emitting diode of the present invention includes a first electrode, which is sequentially arranged on the first electrode, a hole injection layer, a hole transport layer, a quantum dot light emitting layer, an electron transport layer, and a first electrode. Two electrodes, wherein the hole transport layer contains a host material and a thermally activated delayed fluorescent material of 10-40 wt%.

The manufacturing method of the quantum dot light-emitting diode of the present invention includes: step one, taking a glass substrate, and arranging a transparent conductive film on the glass substrate to obtain a first electrode, and then placing it on the transparent conductive film of the first electrode Coating a hole injection layer; step two, coating a hole transport layer on the hole injection layer, wherein the hole transport layer includes a host material and a thermally activated delayed fluorescent material of 10-40 wt%; and Step 3: Coating a quantum dot light emitting layer on the hole transport layer, and then coating an electron transport layer on the quantum dot light emitting layer, and then plating a second electrode on the electron transport layer.

In an embodiment of the present invention, the first electrode includes a glass substrate and a transparent conductive film, and the hole injection layer is disposed on the transparent conductive film.

In an embodiment of the present invention, the host material of the hole transport layer is poly(4-butylphenyldiphenylamine) (Poly-TPD); and The thermally activated delayed fluorescent material is DDCzTrz (9,9',9``,9'''-((6-phenyl-1,3,5-triazine-2,4-diyl)bis(benzene-5,3 ,1-triyl))tetrakis(9H-carbazole)).

In an embodiment of the present invention, the thickness of the hole injection layer is 10-50 nm, the thickness of the hole transport layer is 10-50 nm, the thickness of the quantum dot light-emitting layer is 10-30 nm, and the electron transport layer The thickness of the second electrode is between 30 and 80 nm, and the thickness of the second electrode is between 100 and 300 nm.

In an embodiment of the present invention, the transparent conductive film is an indium tin oxide (ITO) film, and the hole injection layer is made of 3,4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT:PSS), And the quantum dot light-emitting layer is made of cadmium selenide/zinc sulfide (CdSe/Zns) material.

Thereby, the quantum dot light-emitting diode and the manufacturing method thereof of the present invention can effectively improve the brightness and luminous efficiency of the quantum dot light-emitting diode by adding a thermally activated delayed fluorescent material in the hole transport layer, and can maintain color purity.

The purpose of the present invention and its structural and functional advantages will be described in conjunction with specific embodiments as shown in the following figures, so that the examiner can have a deeper and specific understanding of the present invention.

The present invention relates to a quantum dot light-emitting diode and a manufacturing method thereof. It mainly uses a thermally activated delayed fluorescent material as an auxiliary material doped into the host material of the electron hole transport layer to enhance Förster energy transfer , To promote the singlet excitons of the auxiliary material to cross the back gap to the singlet excitons of the host material, so as to improve the brightness and luminous efficiency of the quantum dot light-emitting diode and maintain the color purity.

Please refer to the first figure. The quantum dot light-emitting diode of the present invention includes a first electrode (1), a hole injection layer (2), a hole transport layer (3), and a quantum dot light-emitting layer (4) , An electron transport layer (5) and a second electrode (6); wherein the first electrode (1) includes a glass substrate and a transparent conductive film, and the hole transport layer (3) includes a host material and a thermal activation Delay material.

The manufacturing method of the quantum dot light-emitting diode of the present invention includes: step one, taking a glass substrate, and arranging a transparent conductive layer on the substrate to obtain the first electrode (1), and then coating the first electrode (1) Place a hole injection layer (2); step two, coat a hole transport layer (3) on the hole injection layer (2), wherein the hole transport layer (3) includes a host material and a thermally activated delayed phosphor Optical material; and step three, coating the quantum dot light-emitting layer (4) on the hole transport layer (3), and then coating the electron transport layer (5) on the quantum dot light-emitting layer (4), and then on the electron transport layer (5) The second electrode (6) is plated on.

Wherein, the preparation material of the hole injection layer (2) can be but not limited to PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate), HATNA-F6 (CAS No. 872140-95-9), DNTPD (CAS The number is 199121-98-7), MeO-TPD (CAS number is 122738-21-0), 2T-NATA (CAS number is 185690-41-9), m-MTDATA (CAS number is 124729-98-2) , NATA (CAS No. 105389-36-4), 1T-NATA (CAS No. 185690-39-5), 2T-NATA (CAS No. 185690-41-9), m-MTDATA (CAS No. 124729- 98-2), F4-TCNQ (CAS number 29261-33-4), PPDN (CAS number 215611-93-1), MeO-TPD (CAS number 122738-21-0), MeO-Spiro-TPD (CAS number is 1138220-69-5), NTNPB (CAS number is 1394130-64-3), TPT1 (CAS number is 167218-46-4), HATNA (CAS number is 214-83-5), HATNA-Cl6 (CAS number is 389121-44-2), HATNA-F6 (CAS number is 872140-95-9), 3FTPD-C8, MeOPBI, TNAP (CAS number is 6251-01-0), Di-NPB (CAS number is 292827-46-4), 3DMFL-BPA (CAS number 354987-71-6) and NPB-DPA (CAS number 910058-11-6) at least one of them.

The host material of the hole transport layer (3) can be but not limited to PVK (CAS number 25067-59-8), CBP (CAS number 58328-31-7), Poly-TPD (CAS number 472960-35- 3) Nickel oxide (NiO), HAT-CN (CAS number 105598-27-4), OTPD (CAS number 746636-00-4), HMTPD (CAS number 105465-14-3), TAPC (CAS The number is 58473-78-2), spirro-TPD (CAS number is 1033035-83-4), DOFL-NPB (CAS number is 870197-09-4), DOFL-TPD (CAS number is 439942-97-9) , VNPB (CAS No. 1010396-31-2), ONPB (CAS No. 1431521-16-2), OTPD (CAS No. 746634-00-4), QUPD (CAS No. 864130-79-0), VB -At least one of FNPD (CAS No. 1173170-48-3), X-F6-TAPC, PFNIBT, and 3FTPD-C8.

The thermally activated delayed fluorescent material of the hole transport layer (3) can be but not limited to mPTC (CAS number 194824774-74-2), TZ-SBA (CAS number 2107977-57-9), Cz-TRZ4 ( CAS number is 2061376-84-7), Cz-TRZ3 (CAS number is 2061376-83-6), DMTDAc (CAS number is 1877288-52-2), MFAc-PPM (10-(4-(4,6- diphenylpyrimidin-2-yl)phenyl)-2,7-dimethyl-10H-spiro[acridine-9,9'-fluorene]), SiMCP2 (CAS number 944465-42-3), TBPe (CAS number 80663-92 -9), TPXZPO (CAS number is 2001115-35-9), DMAC-TRZ (CAS number is 1628752-98-6), ACRSA (CAS number is 1206626-95-0), Cz-VPN (CAS number is 1883400 -30-3), TCzTrz (CAS number 180815-40-8), CPC (CAS number 1803330-63-3), CZ-PS (CAS number 1396165-20-0), 2PXZ-TAZ (CAS number 1447998-15-3), CC2BP (CAS No. 1233215-35-4), DMAC-DPS (CAS No. 1477512-32-5), BDPCC-TPTA (CAS No. 1620808-43-6), BCC- TPTA (CAS No. 1361093-61-9), DCzTrz (CAS No. 1106730-48-6), DDCzTrz (CAS No. 1106730-48-6), DMOC-DPS (CAS No. 1477507-77-9), DPCC-TPTA (CAS No. 1620808-42-5), Phen-TRZ (CAS No. 1357066-21-7), Cab-Ph-TRZ (CAS No. 440354-93-8), and 4CZFCN (CAS No. 1819362-10-1) at least one of them.

The material of the quantum dot light-emitting layer (4) The quantum dot light-emitting layer can be, but is not limited to, methylamino lead bromide (MaPbBr ₃ ), tBuCzDBA (CAS number 2171334-46-4), Ir(dmppy-pro) 2tmd (CAS No. 2050041-60-4), CzDBA (CAS No. 2171334-43-1), BPTPA DMQA (CAS No. 188973-32-9), C545T (CAS No. 155306-71-1), Coumarin 6 (CAS The number is 38215-36-0), Px-VPN (CAS number is 1784766-39-7), TmCzTrz (CAS number is 1808158-41-9), Zn(BTZ)2 (CAS number is 58280-31-2) , BA-TTB (CAS No. 223735-62-4), BA-TAD (CAS No. 220721-68-6), BA-NPB (CAS No. 885502-26-1), 2PXZ-OXD (CAS No. 1447998-13-1), Ir(npy)2acac (CAS number 878393-09-0), Ir(3mppy)3 (CAS number 639006-72-7), OP-09, DPASP (CAS number 2005434- 89-7), BDAVBi (CAS number 523977-57-3), DPAVBi (CAS number 119586-44-6), TBPe (CAS number 80663-92-9), Perylene (CAS number 198-55- 0), BCzVBi (CAS number 1475480-90-1), Spiro-BDAVBi (CAS number 436798-89-9), BNP3FL (CAS number 669016-17-5), MDP3FL (CAS number 239476-24- 5), N-BDAVBi (CAS number 1032556-63-0), fac-Ir(Pmb)3, Ac-CNP (CAS number 1883400-34-7), DCJTB (CAS number 200052-70-6) , DCM (CAS number 51325-91-8), DCJT (CAS number 159788-00-8), Eu(dbm)3(Phen) (CAS number 17904-83-5), Ir(btp)2( acac) (CAS number 343978-19-0), Ir(fliq)2(acac) (CAS number 1617506-77-0), TBRb (CAS The serial number is 682806-51-5), Hex-Ir(phq)2(acac) (CAS No. 1404197-18-7) or at least one of cadmium selenide/zinc sulfide (CdSe/ZnS) .

The electron transport layer (5) can be, but is not limited to, TPBi (CAS number 192198-85-9), zinc oxide (ZnO), nano-zinc oxide (ZnO nanoparticle), TPM-TAZ (CAS number 1874199-82-2 ), Liq (CAS number 25387-93-3), BAlq (CAS number 146162-54-1), Bpy-OXD (CAS number 866117-19-3), BP-OXD-Bpy (CAS number 1219827 -28-7), NTAZ (CAS No. 16152-10-6), NBphen (CAS No. 1174006-43-9), Bpy-FOXD (CAS No. 1174006-45-1), 2-NPIP (CAS No. 1234997-42-2), HNBphen (CAS number 923972-84-3), POPy2 (CAS number 721969-93-3), BTB (CAS number 266349-83-1), BmPyPhB (CAS number 1030380 -38-1), DPPS (CAS number 115216-74-7), PY1 (CAS number 1246467-58-2), Bepq2 (CAS number 148896-39-3), TpPyPB (CAS number 921205-02 -9), TmPPPyTz (CAS number 939430-31-6), B3PYMPM (CAS number 925425-96-3), TPyQB (CAS number 1350742-68-5), B4PYMPM (CAS number 1030380-51-8 ), BPy-TP2 (CAS number is 139481-58-1), BIPO (CAS number is 1426143-77-2), Libpp (CAS number is 10498805-81-3), B4PYPPM (CAS number is 1097652-83-9 ), Tm3PyP26PyB (CAS number 1492917-78-8), B3PYPPM (CAS number 1382639-67-9), B4PYPPyPM (CAS number 1382639-70-4), TP3PO (CAS number 1311378-95-6), FPQ-Br, NaQ (CAS No. 2872-54-0), DBimiBphen (CAS No. 1447848-17-0), PO-T2T (CAS No. 1646906-26-4).

In addition, the following specific examples can further prove the scope of practical application of the present invention, but it is not intended to limit the scope of the present invention in any form.

1. Preparation of the quantum dot light-emitting diode of the present invention

(1) Preparation process

In this embodiment, a glass substrate is used as the substrate of the first electrode (1) of the quantum dot light-emitting diode of the present invention, and the glass substrate is cut into a size of 1.5 cm Í 2 cm Í 0.7 mm for subsequent quantum dots. Preparation of point-emitting diodes.

The glass substrate was oscillated with acetone, isopropanol, and deionized water for 15 minutes in order, and finally the glass substrate was blown dry with a nitrogen gun; a transparent conductive film was formed on the surface of the glass substrate by using yellow light lithography technology to make The first electrode (1) is obtained. In this embodiment, the first electrode (1) is a interdigitated transparent electrode, the transparent conductive film is an indium tin oxide (ITO) film, and the sheet resistance value is 11 Ω/sq, which is used as an anode.

Next, spin coating on the transparent conductive film to coat poly 3,4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT:PSS) with a thickness of 10-50 nm, and then bake in an oven , Bake at 120°C for 15 minutes to form the hole injection layer (2), and the preferred thickness of the hole injection layer (2) is 17-32nm;

Then, spin coating on the hole injection layer (2) to coat a mixed material with a thickness of 10-50 nm, then heat it with an electric hot plate, and act on it at 110°C for 30 minutes to form a hole transport layer ( 3) The preferred thickness of the hole transport layer (3) is 12-18 nm; the mixed material contains 10 wt%-40 wt% of the thermally activated delayed fluorescent material DDCzTrz and the remaining weight percentage of the host material Poly-TPD;

Then, spin coating on the hole transport layer (3) to coat cadmium selenide/zinc sulfide (CdSe/ZnS) with a thickness of 10-30 nm, and then heat it with an electric hot plate at 90°C 30 minutes to form the quantum dot light-emitting layer (4), the preferred thickness of the quantum dot light-emitting layer (4) is 12-18 nm;

Then at the quantum dot light emitting layer (4) applied to a thickness of 30-80 nm for the spin coating of nano-zinc oxide (ZnO nanoparticle), then to a hot plate heated at 90 deg.] C for 30 minutes to form an electron transporting Layer (5), and the thickness of the electron transport layer (5) is preferably 40-60 nm;

Finally, by means of thermal evaporation, aluminum (Al) metal with a thickness of 150 nm ± 2 nm is deposited on the electron transport layer (5) to form the second electrode (6). In this embodiment, the second electrode is used as Cathode; the working pressure used in the thermal evaporation step is less than 1×10 ^-6 torr.

In the quantum dot light-emitting diode prepared in this embodiment, the thickness of the hole injection layer (2) is 25 nm, the thickness of the hole transport layer (3) is 25 nm, and the thickness of the quantum dot light-emitting layer (4) is 16 nm, the thickness of the electron transport layer (5) is 55 nm, the thickness of the second electrode (6) is 150 nm, and the light-emitting area is 1×1 mm ² .

The quantum dot light-emitting diode of the present invention is an electroluminescence element. After the current is introduced, the quantum dot light-emitting diode will emit light, and the wavelength of the light emitted is related to the luminescent material used.

(2) Electroluminescence spectrum analysis

In the quantum dot light-emitting diode used in this embodiment, the material used for the hole transport layer (3) includes 0 wt% to 60 wt% of thermally activated delayed fluorescent material DDCzTrz and the remaining weight percentage of the host material Poly-TPD, in which the thermally activated delayed fluorescent material DDCzTrz takes the proportions of 0 wt%, 20 wt%, 40 wt%, 50 wt%, and 60 wt%, respectively, as an example of the present invention.

DDCzTrz is a thermally activated delayed fluorescent material with a chemical formula of C ₆₉ H ₄₃ N _7. Its highest occupied molecular orbital (HOMO) is -6.1 eV and the lowest occupied molecular orbital (HOMO) is -6.1 eV. LUMO) is -2.9 eV, the singlet and triplet energy difference (ΔE _ST ) is 0.27 eV, and the binary value difference is less than 3 eV, which means that the energy band gap is small and the molecules are easily excited. According to previous studies, the light induced by DDCzTrz The luminescence spectrum, the luminescence wavelength is between 400 nm and 600 nm, and the wave front falls at about 455 nm. Also, please refer to the second figure. The absorption spectrum of the quantum dot material (QDs) cadmium selenide/zinc sulfide (CdSe/ZnS) used in this case is clearly compared with the photoluminescence fluorescence spectrum of the thermally activated delay fluorescent material DDCzTrz The overlapped part (please refer to the horizontal line area in the second figure) represents that fluorescence resonance energy transfer can occur between the two materials, that is, the fluorescence emitted by DDCzTrz can excite quantum dot materials (QDs) and make quantum dot materials (QDs) ) It emits visible light with a wavelength of about 600~650 nm.

Please refer to the third figure. In the quantum dot light-emitting diode of this embodiment, the hole transport layer (3) contains 0 wt%-40 wt% thermally activated delayed fluorescent material DDCzTrz and the remaining weight percentage. The host material Poly-TPD; according to the third figure (A), the emission wavelengths of the four quantum dot light-emitting diodes are all between 600 nm and 700 nm, and there is no significant difference in the waveforms; please refer to the third figure ( B) is an enlarged spectrogram for the emission wavelength range of 440 nm to 460 nm. It can be seen that the light emitted by the four sets of quantum dot light-emitting diodes is not emitted by the thermally activated delayed fluorescent material DDCzTrz under the condition of electrical conductivity. Therefore, adding DDCzTrz to the hole transport layer (3) will not affect the color purity of the quantum dot light-emitting diode.

(3) Analysis of driving voltage

In the quantum dot light-emitting diode of this embodiment, the hole transport layer (3) contains 0 wt% to 60 wt% of the thermally activated delayed fluorescent material DDCzTrz and the remaining weight percentage of the host material Poly-TPD, respectively. And test the driving voltage of each quantum dot light-emitting diode. In this experiment, the driving voltage is defined as the voltage when the current density is 100 milliamperes per square meter; please refer to the fourth figure and table 1, when the addition ratio of DDCzTrZ increases , Can reduce the driving voltage of quantum dot light-emitting diodes.

Table I. Hole transport layer Poly-TPD 100 wt% 80 wt% 60 wt% 50 wt% 40 wt% DDCzTrZ 0 wt% 20 wt% 40 wt% 50 wt% 60 wt% Drive voltage (V) 3.8 3.5 3.3 3.2 3.1

(4) Analysis of luminous brightness.

In the quantum dot light-emitting diode of this embodiment, the hole transport layer (3) contains 0 wt% to 60 wt% of the thermally activated delayed fluorescent material DDCzTrz and the remaining weight percentage of the host material Poly-TPD, respectively. And test the maximum luminous brightness (Luminance, L _max ) of each light-emitting diode, the measurement unit is candles per square meter (cd/m ² ). Please refer to Table 2 and Figure 5. The brightness of quantum dot light-emitting diodes with 20 wt% and 40 wt% DDCzTrz added will be higher than that of quantum dot light-emitting diodes without DDCzTrz, but when the proportion of DDCzTrz is high At 40 wt%, the luminous brightness of quantum dot light-emitting diodes will decrease significantly.

Table II Hole transport layer Poly-TPD 100 wt% 80 wt% 60 wt% 50 wt% 40 wt% DDCzTrZ 0 wt% 20 wt% 40 wt% 50 wt% 60 wt% L _max (cd/m ² ) 68496 80889 109046 31070 21486

(5) Analysis of current efficiency

In the quantum dot light-emitting diode of this embodiment, the hole transport layer (3) contains 0 wt% to 60 wt% of the thermally activated delayed fluorescent material DDCzTrz and the remaining weight percentage of the host material Poly-TPD, respectively. And test the current efficiency (CE _max ) of each light-emitting diode. Please refer to Table 3 and Figure 6, the current efficiency of quantum dot light-emitting diodes with 20 wt% and 40 wt% DDCzTrz added is significantly higher than that of the non-additive group, but when the addition ratio of DDCzTrz is higher than 40 wt %, the current efficiency of the quantum dot light-emitting diode will be significantly reduced.

Table Three Hole transport layer Poly-TPD 100 wt% 80 wt% 60 wt% 50 wt% 40 wt% DDCzTrZ 0 wt% 20 wt% 40 wt% 50 wt% 60 wt% CE _max (cd/A) 3.4 4.7 5.2 0.7 0.2

According to the above examples, it can be seen that adding an appropriate proportion of thermally activated delayed fluorescent material in the hole transport layer of the quantum dot light-emitting diode, such as the DDCzTrz used in the example of this case, will reduce the drive of the quantum dot light-emitting diode Voltage, improve the brightness and current efficiency of the quantum dot light-emitting diode; taking the actual embodiment of this case as an example, adding 10 wt to 40 wt% of DDCzTrz in the hole transport layer can significantly reduce the driving voltage and increase the light emission of the quantum dot. The brightness and current efficiency of the polar body will not affect the emission spectrum of the quantum dot light-emitting diode.

In the quantum dot light-emitting diode of the present invention, a thermally activated delayed fluorescent material is added to the host material to enhance Förster resonance energy transfer. Compared with the conventional quantum dot light-emitting diode, it is only Compared with the mechanism of using charge injection to make light-emitting diodes emit light, the present invention uses both an energy conversion mechanism and a charge injection mechanism to simultaneously improve the brightness and current efficiency of quantum dot light-emitting diodes. In this case, thermal activation with high quantum efficiency is selected. Delayed fluorescent materials are used as energy donors in the energy conversion mechanism to promote the back gap of the auxiliary material singlet excitons to the host material singlet excitons, which not only does not affect the emission spectrum of the quantum dot light-emitting diode. Color purity can increase the converted energy and further improve component performance. According to the spectrum analysis chart of the third figure, the emission band of the quantum dot light-emitting diode of the present invention is 620 nm, which can be applied to manufacture red light-emitting diodes.

In summary, the quantum dot light-emitting diode and its manufacturing method of the present invention can indeed achieve the expected use effect through the embodiments disclosed above, and the present invention has not been disclosed before the application. Comply with the provisions and requirements of the Patent Law. If you file an application for a patent for invention in accordance with the law, you are kindly requested to review and grant a quasi-patent.

However, the above-mentioned explanations are only the preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. For those who are familiar with the art, other equivalent changes made according to the characteristics of the present invention are made. Any modification or modification should be regarded as not departing from the design scope of the present invention.

(1): The first electrode (2): Hole injection layer

(3): Hole transmission layer (4): Quantum dot light-emitting layer

(5): Electron transport layer (6): Second electrode

Figure 1: Schematic diagram of the structure of the quantum dot light-emitting diode of the present invention.

Figure 2: Absorption spectrum and fluorescence spectrum of the quantum dot material and thermally activated delay fluorescent material used in the present invention.

Figure 3: The electroluminescence spectrum analysis diagram of the quantum dot light-emitting diode of the present invention.

Figure 4: The driving voltage analysis diagram of the quantum dot light-emitting diode of the present invention.

Figure 5: The luminous brightness analysis diagram of the quantum dot light-emitting diode of the present invention.

Figure 6: Current efficiency analysis diagram of the quantum dot light-emitting diode of the present invention.

without

(1): The first electrode

(2): Hole injection layer

(3): Hole transmission layer

(4): Quantum dot light-emitting layer

(5): Electron transport layer

(6): Second electrode

Claims (8)

A quantum dot light-emitting diode includes a first electrode on which a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a second electrode are sequentially arranged , Wherein the hole transport layer contains a host material and a thermally activated delayed fluorescent material of 10-40wt%, wherein the host material of the hole transport layer is poly[bis(4-phenyl)(4-butyl) Poly(4-butylphenyldiphenylamine), and the thermally activated delayed fluorescent material is DDCzTrz(9,9',9",9"'-((6-phenyl-1,3,5 -triazine-2,4-diyl)bis(benzene-5,3,1-triyl))tetrakis(9H-carbazole)). The quantum dot light-emitting diode according to claim 1, wherein the first electrode includes a glass substrate and a transparent conductive film, and the hole injection layer is disposed on the transparent conductive film. The quantum dot light-emitting diode according to claim 1, wherein the hole injection layer has a thickness of 10-50 nm, the hole transport layer has a thickness of 10-50 nm, and the quantum dot light-emitting layer has a thickness of 10 ~30nm, the thickness of the electron transport layer is 30~80nm, and the thickness of the second electrode is between 100~300nm. The quantum dot light-emitting diode according to claim 2, wherein the transparent conductive film is an indium tin oxide (ITO) film. The quantum dot light-emitting diode according to claim 1, wherein the hole injection layer is made of poly 3,4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT: PSS), and the quantum dot emits light The layer system is made of cadmium selenide/zinc sulfide (CdSe/ZnS) material. A method for preparing the quantum dot light-emitting diode according to claim 1, comprising: Step 1: Take a glass substrate, set a transparent conductive film on the glass substrate to obtain a first electrode, and then coat a hole injection layer on the transparent conductive film of the first electrode; Step 2: The hole injection layer is coated with a hole transport layer, wherein the hole transport layer contains a host material and a thermally activated delayed fluorescent material of 10-40wt%, wherein the host material is poly[bis(4- Phenyl) (4-butylphenyldiphenylamine), the thermally activated delayed fluorescent material is DDCzTrz(9,9',9",9'''-((6-phenyl- 1,3,5-triazine-2,4-diyl)bis(benzene-5,3,1-triyl))tetrakis(9H-carbazole)); Step 3: Coating a quantum dot on the hole transport layer The light-emitting layer, and then coating an electron transport layer on the quantum dot light-emitting layer; and step 4: disposing a second electrode on the electron transport layer. The method according to claim 6, wherein the hole injection layer has a thickness of 10-50 nm, the hole transport layer has a thickness of 10-50 nm, the quantum dot light-emitting layer has a thickness of 10-30 nm, and the electron The thickness of the transmission layer is 30-80 nm, and the thickness of the second electrode is 100-300 nm. The method according to claim 6, wherein the transparent conductive film is an indium tin oxide (ITO) film, and the hole injection layer is made of poly 3,4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT: PSS). ), and the quantum dot light-emitting layer is prepared with cadmium selenide/zinc sulfide (CdSe/ZnS) material.

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