A method for preparing a quasi-two-dimensional blue light LED device

Abstract

The present invention is applicable to the field of light-emitting diodes, and provides a method for preparing a quasi-two-dimensional blue light LED device, wherein the blue light quasi-two-dimensional LED device is composed of a quasi-two-dimensional perovskite film, a charge transport layer and a metal electrode, wherein the quasi-two-dimensional perovskite film is composed of a pure bromine-based three-dimensional perovskite plus a suitable long-chain organic ligand. In the process of device preparation, the present invention mixes metal nanoclusters with a traditional transport layer, adjusts the electrical properties of the original transport layer, thereby achieving the effect of balanced carrier transport, and ultimately improving the performance of the perovskite light-emitting device, having the advantages of simple preparation process and high efficiency, and solving the problem of low efficiency of existing blue light quasi-two-dimensional LED devices.

Description

Technical Field

[0001] The invention belongs to the field of light emitting diodes, and in particular relates to a method for preparing a quasi-two-dimensional blue light LED device. Background Art

[0002] Quasi-two-dimensional metal halide perovskite materials hold great promise for light-emitting diode and display applications due to their high photoluminescence quantum yield, tunable optical band gap, excellent color purity and low-cost solution processability.

[0003] However, the photoelectric properties of light-emitting diodes using perovskite materials as the light-emitting layer are still far inferior to those of organic light-emitting diodes. On the one hand, it is difficult to control the crystallization process of the perovskite film solution, resulting in poor film crystallization quality and uneven phase distribution, resulting in too low energy transfer efficiency, and thus too many non-radiative recombination defects; on the other hand, the lack of a transport layer with a suitable energy level makes carrier injection difficult, resulting in unbalanced carrier transfer in the device, resulting in low device efficiency, which seriously restricts the industrial application of perovskite films and their equipment. For quasi-two-dimensional blue LED devices, due to the large blue light emission band gap, its HOMO energy level is deep. The lack of hole transport materials with both suitable mobility and energy levels has always been one of the main reasons that have plagued the further improvement of the efficiency of quasi-two-dimensional blue LED devices. For this reason, we propose a method for preparing quasi-two-dimensional blue LED devices. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a method for preparing a quasi-two-dimensional blue light LED device, aiming to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing a quasi-two-dimensional blue light LED device comprises the following steps:

[0007] Step 1: The ITO substrate was repeatedly cleaned with deionized water, ethanol and acetone, and then cleaned with a UV ozone machine for 20 minutes;

[0008] Step 2: Deposit the PEDOT:PSS solution onto the surface of the substrate in step 1 by spin coating, and perform post-annealing at 150° C. Dissolve the mixed material of the conductive polymer, metal nanoclusters and conductive polymer in an organic reagent, and deposit it on the surface of the substrate by spin coating, and perform post-annealing at 150° C.;

[0009] Step 3: Dissolve appropriate amounts of lead iodide, phenylbutylammonium bromide and cesium bromide in 1 ml of DMSO solution to form a perovskite precursor solution;

[0010] Step 4: Add an appropriate amount of the perovskite precursor solution in step 3 to the surface of the substrate in step 2, and then prepare a thin film by spin coating. At a certain time, add 150 microliters of anti-solvent to the surface of the perovskite film. The anti-solvent is one of ethyl acetate, chlorobenzene and toluene, so that the film can be crystallized quickly. Then, the film is placed on a heating table for later annealing and crystallization.

[0011] Step 5: Place the film obtained in step 4 into an evaporator to evaporate the electron transport layer and the metal aluminum electrode.

[0012] Furthermore, in step 2, the conductive polymer is one of PVK, Poly-TPD, PTAA and TFB.

[0013] Furthermore, in step 2, in the mixed material of metal nanoclusters and conductive polymers, the metal nanoclusters are one of oil-soluble gold nanoclusters, oil-soluble silver nanoclusters and oil-soluble copper nanoclusters.

[0014] Furthermore, in the step 2, in the mixed material of metal nanoclusters and conductive polymer, the proportion of metal nanoclusters in the mixed material is 5%-55%.

[0015] Furthermore, the metal nanoclusters are used to enhance hole conductivity.

[0016] Furthermore, in step 2, the organic reagent is one of DMSO, DMF, CB and m-xylene.

[0017] Furthermore, in step 5, the electron transport material is one of TPBi / LiF, TPBi / Liq, Tmpypb / LiF and Tmpypb / Liq.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The preparation method of the quasi-two-dimensional blue light LED device dopes oil-soluble metal nanoclusters into an organic conductive polymer, effectively improving the injection and transmission of hole carriers of the quasi-two-dimensional blue light LED device; utilizing the molecular state characteristics of the metal nanoclusters, the metal can be doped into the transmission layer in another way, and the metallic property is utilized to improve the conductivity and carrier mobility of the conductive polymer; at the same time, the π-π stacking between the ligands of the metal nanoclusters and the benzene rings in the conductive polymer is utilized, so that the energy level difference between the HOMO energy level of the hole transport layer and the HOMO energy level of the quasi-two-dimensional blue light perovskite light-emitting layer is smaller, thereby improving the hole injection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a comparison diagram of the film roughness before and after the experimental optimization of an embodiment of the present invention.

[0021] Figure 2 This is a comparison chart of the film conductivity before and after the experimental optimization in the embodiment of the present invention.

[0022] Figure 3 This is a comparison chart of the carrier mobility of the thin film before and after the experimental optimization in the embodiment of the present invention.

[0023] Figure 4 This is a comparison diagram of device current density and turn-on voltage before and after experimental optimization in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0026] Example 1

[0027] An embodiment of the present invention provides a method for preparing a quasi-two-dimensional blue light LED device, comprising the following steps:

[0028] Step 1: The ITO substrate was repeatedly cleaned with deionized water, ethanol and acetone, and then cleaned with a UV ozone machine for 20 minutes;

[0029] Step 2: Deposit the PEDOT:PSS solution onto the surface of the substrate in step 1 by spin coating, and perform post-annealing at 150°C;

[0030] Step 3: dissolve an appropriate amount of TFB in CB, deposit it onto the substrate surface of step 2 by spin coating in a nitrogen glove box, and perform post-annealing at 150°C;

[0031] Step 4: dissolve an appropriate amount of PVK and oil-soluble silver nanoclusters in CB, deposit them on the substrate surface of step 3 by spin coating in a nitrogen glove box, and perform post-annealing at 150°C;

[0032] Step 5: Dissolve appropriate amounts of lead iodide, phenylbutylammonium bromide and cesium bromide in 1 ml of DMSO solution to form a perovskite precursor solution;

[0033] Step 6: Add an appropriate amount of the perovskite precursor solution in step 5 to the surface of the substrate in step 4, and then prepare a thin film by spin coating. At a certain time, 150 microliters of ethyl acetate is added as an anti-solvent to the surface of the perovskite film to make the film crystallize quickly, and then the film is placed on a heating table for later annealing and crystallization;

[0034] Step 7: Place the film obtained in step 6 into an evaporator to evaporate the electron transport layer TPBi / Liq and the metal aluminum electrode.

[0035] In the embodiment of the present invention, the perovskite film is composed of a quasi-two-dimensional perovskite film. The quasi-two-dimensional film is constructed by adding long-chain organic groups to a three-dimensional perovskite to enhance the quantum confinement effect, so that the device luminescence peak is blue-shifted; preferably, the incorporation of metal nanoclusters cannot increase the roughness of the optimized transport layer film by more than 50% compared with that before optimization, and the roughness of the perovskite layer film prepared by the spin coating method cannot increase by more than 50% compared with that before optimization; the incorporation of metal nanoclusters improves the hole conductivity, improves the energy level, and makes the hole transport layer and the light-emitting layer energy level more matched, thereby improving the hole injection efficiency, which is specifically manifested in the reduction of the turn-on voltage (the voltage at a brightness of 1 candela per square meter). See Figure 1-Figure 4 , silver nanoclusters are added as dopants into the conductive polymer PVK as a hole transport layer, which improves the hole mobility of PVK, improves the energy level of PVK, realizes energy-level matching carrier injection, and improves the carrier injection efficiency. Metal nanoclusters, because of their transition scale, have both metallic and molecular properties, which can solve the limitations of inorganic silver salts and organic ligands acting alone, and are a very good way to improve transport materials. Through appropriate concentration doping, metal nanoparticles will not significantly improve the film-forming properties of the transport layer, and will not affect the film-forming properties of perovskites. The doping of silver nanoclusters can significantly enhance the transport and injection of hole carriers, build a balanced carrier transport, and achieve high-brightness and high-efficiency blue light LED device performance.

[0036] Example 2

[0037] An embodiment of the present invention provides a method for preparing a quasi-two-dimensional blue light LED device, comprising the following steps:

[0038] Step 1: The ITO substrate was repeatedly cleaned with deionized water, ethanol and acetone, and then cleaned with a UV ozone machine for 20 minutes;

[0039] Step 2: Deposit the PEDOT:PSS solution onto the surface of the substrate in step 1 by spin coating, and perform post-annealing at 150°C;

[0040] Step 3: dissolve an appropriate amount of Poly-TPD in m-xylene, deposit it on the surface of the substrate in step 2 by spin coating in a nitrogen glove box, and perform post-annealing at 150°C;

[0041] Step 4: dissolving an appropriate amount of PTAA and oil-soluble copper nanoclusters in CB, depositing them onto the substrate surface of step 3 by spin coating in a nitrogen glove box, and performing post-annealing at 150°C;

[0042] Step 5: Dissolve appropriate amounts of lead iodide, phenylbutylammonium bromide and cesium bromide in 1 ml of DMSO solution to form a perovskite precursor solution;

[0043] Step 6: Add an appropriate amount of the perovskite precursor solution in step 5 to the surface of the substrate in step 4, and then prepare a thin film by spin coating. At a certain time, 150 microliters of chlorobenzene is added as an anti-solvent to the surface of the perovskite film to make the film crystallize quickly, and then put the film on a heating table for later annealing and crystallization;

[0044] Step 7: Place the film obtained in step 6 into an evaporator to evaporate the electron transport layer TPBi / LiF and the metal aluminum electrode.

[0045] Example 3

[0046] An embodiment of the present invention provides a method for preparing a quasi-two-dimensional blue light LED device, comprising the following steps:

[0047] Step 1: The ITO substrate was repeatedly cleaned with deionized water, ethanol and acetone, and then cleaned with a UV ozone machine for 20 minutes;

[0048] Step 2: Deposit the PEDOT:PSS solution onto the surface of the substrate in step 1 by spin coating, and perform post-annealing at 150°C;

[0049] Step 3: Dissolve an appropriate amount of TFB in DMSO, deposit it onto the substrate surface of step 2 by spin coating in a nitrogen glove box, and perform post-annealing at 150°C;

[0050] Step 4: dissolving an appropriate amount of Poly-TPD and oil-soluble copper nanoclusters in CB, depositing them onto the substrate surface of step 3 by spin coating in a nitrogen glove box, and performing post-annealing at 150°C;

[0051] Step 5: Dissolve appropriate amounts of lead iodide, phenylbutylammonium bromide and cesium bromide in 1 ml of DMSO solution to form a perovskite precursor solution;

[0052] Step 6: Add an appropriate amount of the perovskite precursor solution in step 5 to the surface of the substrate in step 4, and then prepare a thin film by spin coating. At a certain time, 150 microliters of ethyl acetate is added as an anti-solvent to the surface of the perovskite film to make the film crystallize quickly, and then the film is placed on a heating table for later annealing and crystallization;

[0053] Step 7: Place the film obtained in step 6 into an evaporator to evaporate the electron transport layer TPBi / Liq and the metal aluminum electrode.

[0054] Example 4

[0055] An embodiment of the present invention provides a method for preparing a quasi-two-dimensional blue light LED device, comprising the following steps:

[0056] Step 1: The ITO substrate was repeatedly cleaned with deionized water, ethanol and acetone, and then cleaned with a UV ozone machine for 20 minutes;

[0057] Step 2: Deposit the PEDOT:PSS solution onto the surface of the substrate in step 1 by spin coating, and perform post-annealing at 150°C;

[0058] Step 3: Dissolve an appropriate amount of TFB in DMSO, deposit it onto the substrate surface of step 2 by spin coating in a nitrogen glove box, and perform post-annealing at 150°C;

[0059] Step 4: dissolving an appropriate amount of PTAA and oil-soluble copper nanoclusters in CB, depositing them onto the substrate surface of step 3 by spin coating in a nitrogen glove box, and performing post-annealing at 150°C;

[0060] Step 5: Dissolve appropriate amounts of lead iodide, phenylbutylammonium bromide and cesium bromide in 1 ml of DMSO solution to form a perovskite precursor solution;

[0061] Step 6: Add an appropriate amount of the perovskite precursor solution in step 5 to the surface of the substrate in step 4, and then prepare a thin film by spin coating. At a certain time, 150 microliters of ethyl acetate is added as an anti-solvent to the surface of the perovskite film to make the film crystallize quickly, and then the film is placed on a heating table for later annealing and crystallization;

[0062] Step 7: Place the film obtained in step 6 into an evaporator to evaporate the electron transport layer Tmpypb / Liq and the metal aluminum electrode.

[0063] Example 5

[0064] An embodiment of the present invention provides a method for preparing a quasi-two-dimensional blue light LED device, comprising the following steps:

[0065] Step 1: The ITO substrate was repeatedly cleaned with deionized water, ethanol and acetone, and then cleaned with a UV ozone machine for 20 minutes;

[0066] Step 2: Deposit the PEDOT:PSS solution onto the surface of the substrate in step 1 by spin coating, and perform post-annealing at 150°C;

[0067] Step 3: Dissolve an appropriate amount of Poly-TPD in CB, deposit it onto the substrate surface of step 2 by spin coating in a nitrogen glove box, and perform post-annealing at 150°C;

[0068] Step 4: dissolve an appropriate amount of PVK and oil-soluble silver nanoclusters in CB, deposit them on the substrate surface of step 3 by spin coating in a nitrogen glove box, and perform post-annealing at 150°C;

[0069] Step 5: Dissolve appropriate amounts of lead iodide, phenylbutylammonium bromide and cesium bromide in 1 ml of DMSO solution to form a perovskite precursor solution;

[0070] Step 6: Add an appropriate amount of the perovskite precursor solution in step 5 to the surface of the substrate in step 4, and then prepare a thin film by spin coating. At a certain time, 150 microliters of ethyl acetate is added as an anti-solvent to the surface of the perovskite film to make the film crystallize quickly, and then the film is placed on a heating table for later annealing and crystallization;

[0071] Step 7: Place the film obtained in step 6 into an evaporator to evaporate the electron transport layer Tmpypb / Liq and the metal aluminum electrode.

[0072] Example 6

[0073] An embodiment of the present invention provides a method for preparing a quasi-two-dimensional blue light LED device, comprising the following steps:

[0074] Step 1: The ITO substrate was repeatedly cleaned with deionized water, ethanol and acetone, and then cleaned with a UV ozone machine for 20 minutes;

[0075] Step 2: Deposit the PEDOT:PSS solution onto the surface of the substrate in step 1 by spin coating, and perform post-annealing at 150°C;

[0076] Step 3: dissolving an appropriate amount of PTAA and oil-soluble silver nanoclusters in CB, depositing them onto the substrate surface of step 2 by spin coating in a nitrogen glove box, and performing post-annealing at 150°C;

[0077] Step 4: Dissolve appropriate amounts of lead iodide, phenylbutylammonium bromide and cesium bromide in 1 ml of DMSO solution to form a perovskite precursor solution;

[0078] Step 5: Add an appropriate amount of the perovskite precursor solution in step 4 to the surface of the substrate in step 3, and then prepare a thin film by spin coating. At a certain time, 150 microliters of ethyl acetate is added as an anti-solvent to the surface of the perovskite film to make the film crystallize quickly, and then the film is placed on a heating table for later annealing and crystallization;

[0079] Step 6: Place the film obtained in step 5 into an evaporator to evaporate the electron transport layer Tmpypb / Liq and the metal aluminum electrode.

[0080] Example 7

[0081] An embodiment of the present invention provides a method for preparing a quasi-two-dimensional blue light LED device, comprising the following steps:

[0082] Step 1: The ITO substrate was repeatedly cleaned with deionized water, ethanol and acetone, and then cleaned with a UV ozone machine for 20 minutes;

[0083] Step 2: Deposit the PEDOT:PSS solution onto the surface of the substrate in step 1 by spin coating, and perform post-annealing at 150°C;

[0084] Step 3: dissolving an appropriate amount of PVK and oil-soluble copper nanoclusters in DMF, depositing them onto the substrate surface of step 2 by spin coating in a nitrogen glove box, and performing post-annealing at 150° C.;

[0085] Step 4: Dissolve appropriate amounts of lead iodide, phenylbutylammonium bromide and cesium bromide in 1 ml of DMSO solution to form a perovskite precursor solution;

[0086] Step 5: Add an appropriate amount of the perovskite precursor solution in step 4 to the surface of the substrate in step 3, and then prepare a thin film by spin coating. At a certain time, 150 microliters of ethyl acetate is added as an anti-solvent to the surface of the perovskite film to make the film crystallize quickly, and then the film is placed on a heating table for later annealing and crystallization;

[0087] Step 6: Place the film obtained in step 5 into an evaporator to evaporate the electron transport layer Tmpypb / Liq and the metal aluminum electrode.

[0088] The working principle of the present invention is:

[0089] The preparation method of the quasi-two-dimensional blue light LED device dopes oil-soluble metal nanoclusters into an organic conductive polymer, effectively improving the injection and transmission of hole carriers of the quasi-two-dimensional blue light LED device; utilizing the molecular state characteristics of the metal nanoclusters, the metal can be doped into the transmission layer in another way, and the metallic property is utilized to improve the conductivity and carrier mobility of the conductive polymer; at the same time, the π-π stacking between the ligands of the metal nanoclusters and the benzene rings in the conductive polymer is utilized, so that the energy level difference between the HOMO energy level of the hole transport layer and the HOMO energy level of the quasi-two-dimensional blue light perovskite light-emitting layer is smaller, thereby improving the hole injection efficiency.

[0090] The above are only preferred embodiments of the present invention. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These should also be regarded as the protection scope of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for preparing a quasi-two-dimensional blue light LED device, characterized in that: The following steps are involved: Step 1: The ITO substrate was repeatedly cleaned with deionized water, ethanol and acetone, and then cleaned with a UV ozone machine for 20 minutes; Step 2: Deposit the PEDOT:PSS solution onto the surface of the substrate in step 1 by spin coating, and perform post-annealing at 150° C. Dissolve the mixed material of the conductive polymer, metal nanoclusters and conductive polymer in an organic reagent, and deposit it on the surface of the substrate by spin coating, and perform post-annealing at 150° C.; Step 3: Dissolve appropriate amounts of lead iodide, phenylbutylammonium bromide and cesium bromide in 1 ml of DMSO solution to form a perovskite precursor solution; Step 4: Add an appropriate amount of the perovskite precursor solution in step 3 to the surface of the substrate in step 2, and then prepare a thin film by spin coating. At a certain time, add 150 microliters of anti-solvent to the surface of the perovskite film. The anti-solvent is one of ethyl acetate, chlorobenzene and toluene, so that the film can be crystallized quickly. Then, the film is placed on a heating table for later annealing and crystallization. Step 5: Place the film obtained in step 4 into an evaporator to evaporate the electron transport layer and the metal aluminum electrode.

2. The method for preparing a quasi-two-dimensional blue light LED device according to claim 1, characterized in that: In the step 2, the conductive polymer is one of PVK, Poly-TPD, PTAA and TFB.

3. The method for preparing a quasi-two-dimensional blue light LED device according to claim 2, characterized in that: In the step 2, in the mixed material of metal nanoclusters and conductive polymers, the metal nanoclusters are one of oil-soluble gold nanoclusters, oil-soluble silver nanoclusters and oil-soluble copper nanoclusters.

4. The method for preparing a quasi-two-dimensional blue light LED device according to claim 3, characterized in that: In the step 2, in the mixed material of metal nanoclusters and conductive polymer, the proportion of metal nanoclusters in the mixed material is 5%-55%.

5. The method for preparing a quasi-two-dimensional blue light LED device according to claim 4, characterized in that: The metal nanoclusters are used to enhance hole conductivity.

6. The method for preparing a quasi-two-dimensional blue light LED device according to claim 4, characterized in that: In the step 2, the organic reagent is one of DMSO, DMF, CB and m-xylene.

7. The method for preparing a quasi-two-dimensional blue light LED device according to claim 1, characterized in that: In the step 5, the electron transport material is one of TPBi / LiF, TPBi / Liq, Tmpypb / LiF and Tmpypb / Liq.

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