High-resolution perovskite quantum dot light-emitting layer with quick response function and preparation method of high-resolution perovskite quantum dot light-emitting layer

Abstract

The invention discloses a high-resolution perovskite quantum dot light-emitting layer with a quick response function and a preparation method of the high-resolution perovskite quantum dot light-emitting layer, and the preparation method comprises synthesis of perovskite quantum dots with quick electrical response characteristics and preparation of the high-resolution perovskite quantum dot light-emitting layer. The quantum dot material with the rapid electrical response characteristic is synthesized by using ionic liquid as a functional ligand, and the high-resolution quantum dot light-emitting layer is formed by spin-coating on a high-resolution patterned hole transport layer groove (bank). The quantum dot material which takes the ionic liquid as the ligand and has a rapid electrical response characteristic is used as the light-emitting layer in the high-resolution device, so that the electrical response speed of the device is greatly improved, the device is turned on under the stimulation of electric pulses, and the stable response time of less than 5 microseconds is achieved; and the requirement of high refresh rate of the perovskite quantum dot high-resolution device in future display application is met.

Description

Technical Field

[0001] The present invention relates to the field of perovskite quantum dot display technology, in particular to a high-resolution perovskite quantum dot light-emitting layer with a rapid response function and a preparation method thereof. Background Art

[0002] With the rapid development of the display industry, OLED display technology has been actually applied to people's daily life, and QLED display technology is hailed as the next generation of new display technology. Therefore, the development of new quantum dot display materials is a problem that must be faced. Since 2014, perovskite quantum dot light-emitting diodes have gradually been developed and studied. After several years of development, the performance of advanced red and green perovskite quantum dot light-emitting diodes has exceeded 28%, and dark blue has also exceeded 10%. These results show that perovskite quantum dots are expected to be used as luminescent materials for future display technologies. However, when applied to displays, it is not only required to have pixelation, but also a high refresh rate when the screen switches, which is crucial for display. However, there are currently few research reports in this area. How to solve the response speed of the device so that it meets the requirements of high refresh rate is a major problem for future perovskite quantum dot materials as QLED displays. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a high-resolution perovskite quantum dot light-emitting layer with a fast response function and a preparation method thereof. By using ionic liquids as functional ligands to synthesize perovskite quantum dots, the luminescence performance of the quantum dots is effectively improved, and a perovskite quantum dot light-emitting layer with fast electrical response characteristics is obtained. The high-resolution perovskite quantum dot light-emitting diode prepared for this purpose has an excellent response speed under voltage stimulation and can meet the display requirements of high refresh rates.

[0004] To achieve the above object, the present invention adopts the following technical solution: a method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function, comprising the following steps: Step 1: Synthesize perovskite quantum dots with fast electrical response characteristics using ionic liquids as functional ligands; Step 2: Prepare a high-resolution perovskite quantum dot light-emitting layer by spin coating on a patterned polymer template previously transferred onto a hole transport layer.

[0005] In a preferred embodiment, the preparation of the ionic liquid includes: before adding the A-site solvent cesium carbonate to crystallize quantum dots, adding a 5 mg / ml concentration of ionic liquid chlorobenzene solution to a previously prepared B-site solvent lead bromide chlorobenzene solution, injecting the cesium carbonate solvent into the lead bromide chlorobenzene solution to crystallize into perovskite, and synthesizing high-performance perovskite QDs.

[0006] In a preferred embodiment, step 2 specifically comprises: using a patterned gravure PDMS to imprint a PVB polymer to form microcolumns (21), then spin-coating PMMA (22), and finally washing away the PVB with ethanol to leave a honeycomb-patterned PMMA template, transferring the PMMA template to the PTAA functional layer (23), and finally spin-coating QD to form a high-resolution QD light-emitting layer (24); before imprinting the PVB polymer on the PDMS, the PDMS is first treated with UV-ozone to make the PDMS more hydrophilic; the hole injection layer PEDOT:PSS and the hole transport layer PTAA are respectively deposited on an ITO glass substrate treated with ozone for more than 15 minutes by spin coating.

[0007] In a preferred embodiment, the material for preparing the perovskite quantum dots is all-inorganic perovskite or organic-inorganic hybrid perovskite, and the luminescent wavelength is adjusted within the range of 510nm-525nm.

[0008] In a preferred embodiment, the perovskite quantum dot material is synthesized by a room temperature ligand-assisted precipitation method.

[0009] In a preferred embodiment, the types of ionic liquids include all ionic liquids whose cations are imidazoles, such as imidazole ionic liquids whose anions are: tetrafluoroborate BF4⁻, hexafluorophosphate PF6⁻, trifluoromethanesulfonate CF3SO3⁻.

[0010] In a preferred embodiment, the ionic liquid is added during the synthesis of perovskite quantum dots as a regulating ligand for crystallization.

[0011] In a preferred embodiment, the ionic liquid is added after the synthesis of quantum dots to serve as a post-defect compensation ligand.

[0012] In a preferred embodiment, the high-resolution perovskite quantum dot light-emitting layer is prepared by deposition through nanoimprinting, inkjet printing, transfer printing or photolithography.

[0013] The present invention also provides a high-resolution perovskite quantum dot light-emitting layer with a rapid response function, which is prepared by the method for preparing a high-resolution perovskite quantum dot light-emitting layer with a rapid response function.

[0014] The present invention also provides a high-resolution perovskite quantum dot light-emitting diode with a fast response function, including a high-resolution perovskite quantum dot light-emitting layer with a fast response function, wherein the high-resolution perovskite quantum dot light-emitting layer with a fast response function is prepared by the preparation method of the high-resolution perovskite quantum dot light-emitting layer with a fast response function.

[0015] The present invention also provides an application of a high-resolution perovskite quantum dot light-emitting diode with a fast response function, which uses the high-resolution perovskite quantum dot light-emitting diode with a fast response function. The high-resolution perovskite quantum dot light-emitting diode with a fast response function is used in the fields of computer, mobile phone, television or e-book display.

[0016] Compared with the prior art, the present invention has the following beneficial effects: by using high-performance perovskite quantum dots modified with ionic liquid as the light-emitting layer, a continuous positive pulse voltage signal is applied to the device, thereby observing the time taken for the brightness of the device to rise from the start of the pulse stimulation to the final rise to 90% of the maximum stable brightness value (defined as the response speed). Based on the improvement of the light-emitting layer material by ionic liquid, the response speed of the device is greatly improved, giving the device the function of fast response, and developing future perovskite QLED display technology with high refresh rate capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the ionic liquid-assisted synthesis of quantum dot light-emitting materials for a high-resolution perovskite quantum dot light-emitting diode with rapid response function described in the present invention.

[0018] Figure 2 This is a schematic diagram of the process of preparing a patterned light-emitting layer of a high-resolution perovskite quantum dot light-emitting diode with a fast response function described in the present invention.

[0019] Figure 3 This is a device structure and response speed test diagram of a high-resolution perovskite quantum dot light-emitting diode with fast response function described in the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0023] like Figure 1This is a schematic diagram of the ionic liquid-assisted synthesis of a quantum dot light-emitting material for a high-resolution perovskite quantum dot light-emitting diode with a fast response function according to the present invention, specifically comprising: Before adding the A-site solvent cesium carbonate to crystallize quantum dots, a 5 mg / ml concentration of ionic liquid chlorobenzene solution is added to the previously prepared B-site solvent lead bromide chlorobenzene solution11. The cesium carbonate solvent is injected into the lead bromide solution to crystallize into perovskite12. The added ionic liquid will effectively improve the crystallization process to ensure the synthesis of high-performance perovskite QDs, which have fast electrical response characteristics when applied to devices.

[0024] Furthermore, after the perovskite is crystallized in step one, a long-faced dispersing ligand DDAB is added in step two to ensure the dispersion stability of the quantum dots.

[0025] Furthermore, in step 3, the anti-solvent ethyl acetate is added to precipitate the crude perovskite solution obtained by centrifugation 13.

[0026] Further, in step 4, the centrifuged perovskite QD solution is collected for later use 14.

[0027] like Figure 2 The present invention is a schematic diagram of a process for preparing a patterned light-emitting layer of a high-resolution perovskite quantum dot light-emitting diode with a fast response function, which specifically includes: Use a patterned gravure PDMS to imprint PVB polymer to form microcolumns 21, then spin-coat PMMA 22, and finally wash off the PVB with ethanol, leaving a honeycomb-patterned PMMA template, transfer the PMMA template to the PTAA functional layer 23, and finally spin-coat QD to form a high-resolution QD light-emitting layer 24. Before PDMS is imprinted with PVB polymer, it is first treated with UV-ozone to make PDMS more hydrophilic. The hole injection layer PEDOT:PSS and the hole transport layer PTAA are deposited on the ITO glass substrate treated with ozone for more than 15 minutes by spin coating.

[0028] Furthermore, after the QD is spin-coated into a film, it is taken into an evaporator to deposit the electron transport layer TPBI, the LiF layer and the cathode AL layer in sequence under high vacuum.

[0029] like Figure 3 The device structure and response speed test diagram of a high-resolution perovskite quantum dot light-emitting diode with a fast response function described in the present invention specifically include: The fast response function of the LED was tested using the TREL test system 31, mainly comparing the TREL rising edge time. The response speed of the device using the QD improved by ionic liquid as the light-emitting layer was improved by tens of microseconds compared with the standard device without ionic liquid 32. Finally, the high-resolution perovskite quantum dot light-emitting diode we prepared has an ultra-fast response speed of 4.6 microseconds 33, which can meet the high refresh rate requirements of the display device. The synthesis of the perovskite quantum dots is assisted by ionic liquid as a functional ligand. These quantum dots have excellent luminescence properties, and the assembled light-emitting layer has fast electrical response characteristics.

[0030] The high-resolution light-emitting layer preparation method first prepares a patterned template by nanoimprinting technology, then transfers it to a hole transport layer that has been spin-coated in advance, then spin-coats perovskite quantum dots, and finally deposits an electron transport layer and metal electrodes by vacuum thermal evaporation technology to complete the device preparation.

[0031] The above are preferred embodiments of the present invention. Any changes made according to the technical solution of the present invention, as long as the resulting functions do not exceed the scope of the technical solution of the present invention, belong to the protection scope of the present invention.

Claims

1. A method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function, characterized in that: The following steps are involved: Step 1: Synthesize perovskite quantum dots with fast electrical response characteristics using ionic liquids as functional ligands; Step 2: Prepare a high-resolution perovskite quantum dot light-emitting layer by spin coating on a patterned polymer template previously transferred onto a hole transport layer.

2. The method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function according to claim 1, characterized in that: The preparation of the ionic liquid includes: before adding the A-site solvent cesium carbonate to crystallize and form quantum dots, adding a 5 mg / ml ionic liquid chlorobenzene solution to a previously prepared B-site solvent lead bromide chlorobenzene solution, injecting the cesium carbonate solvent into the lead bromide chlorobenzene solution to crystallize and form perovskite, thereby synthesizing high-performance perovskite QDs.

3. The method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function according to claim 1, characterized in that: The step 2 specifically comprises: using a patterned gravure PDMS to imprint a PVB polymer to form microcolumns (21), then spin-coating PMMA (22), finally washing away the PVB with ethanol to leave a honeycomb-patterned PMMA template, transferring the PMMA template to the PTAA functional layer (23), and finally spin-coating QDs to form a high-resolution QD light-emitting layer (24); before imprinting the PVB polymer on the PDMS, the PDMS is first treated with UV-ozone to make the PDMS more hydrophilic; the hole injection layer PEDOT:PSS and the hole transport layer PTAA are respectively deposited on an ITO glass substrate treated with ozone for more than 15 minutes by spin coating.

4. The method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function according to claim 1, characterized in that: The material for preparing the perovskite quantum dots is all-inorganic perovskite or organic-inorganic hybrid perovskite, and the luminescent wavelength is adjusted within the range of 510nm-525nm.

5. The method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function according to claim 1, characterized in that: The perovskite quantum dot material is synthesized by a room temperature ligand-assisted precipitation method.

6. The method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function according to claim 1, characterized in that: The types of ionic liquids include all ionic liquids whose cations are imidazoles, such as imidazole ionic liquids whose anions are: tetrafluoroborate BF4⁻, hexafluorophosphate PF6⁻, trifluoromethanesulfonate CF3SO3⁻.

7. The method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function according to claim 6, characterized in that: The ionic liquid is added during the synthesis of perovskite quantum dots as a regulating ligand for crystallization.

8. The method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function according to claim 6, characterized in that: The ionic liquid is added after the synthesis of the quantum dots as a post-defect compensation ligand.

9. The method for preparing a high-resolution perovskite quantum dot light-emitting layer with a fast response function according to claim 1, characterized in that: The high-resolution perovskite quantum dot light-emitting layer is prepared by deposition through nano-imprinting, inkjet printing, transfer printing or photolithography.

10. A high-resolution perovskite quantum dot light-emitting layer with fast response function, characterized in that: The high-resolution perovskite quantum dot light-emitting layer with fast response function is prepared by the preparation method of any one of claims 1 to 9.

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