CN111048672B - Perovskite electroluminescence-based white light LED and preparation method thereof - Google Patents
Perovskite electroluminescence-based white light LED and preparation method thereof Download PDFInfo
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- CN111048672B CN111048672B CN201911058230.2A CN201911058230A CN111048672B CN 111048672 B CN111048672 B CN 111048672B CN 201911058230 A CN201911058230 A CN 201911058230A CN 111048672 B CN111048672 B CN 111048672B
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Abstract
The invention discloses a preparation method of a perovskite electroluminescent white light LED, which comprises the following steps: (1) cleaning the anode, drying after cleaning, and pretreating the dried anode; (2) depositing a hole injection layer by adopting a spin coating process, and carrying out heat treatment; (3) preparing a yellow perovskite solution and a blue light polymer solution, sequentially spin-coating a yellow perovskite layer and a blue light polymer layer, and performing heat treatment processing after each spin-coating layer; the processed yellow perovskite layer and the processed blue polymer layer form an emitting active layer; (4) transferring the device into a vacuum evaporation bin, and carrying out evaporation on the electron injection layer and the cathode; (5) the device was encapsulated with epoxy and a glass cover plate. The invention provides a new idea for realizing white light electroluminescence, namely, the white light LED based on perovskite electroluminescence is prepared by adopting yellow perovskite and blue light polymer, and the electroluminescence spectrum of the white light LED can cover the whole visible light area.
Description
Technical Field
The invention relates to the technical field of optical display, in particular to a perovskite electroluminescence-based white light LED and a preparation method thereof.
Background
White light display (illumination) is an important research topic in the optical field, because white light illumination is ubiquitous, the white light illumination has a wide application prospect, and the improvement of the efficiency of white light illumination materials can save tens of thousands of energy sources for the whole world every year.
In recent years, organic-inorganic hybrid perovskite materials have attracted attention due to superior photoelectric and physical properties of high absorption coefficient, high and balanced electron and hole mobility, high defect tolerance, tunability of band gap, tunability of exciton confinement energy, and tunability of nanostructure, and the perovskite structure can be simply constructed as a polycrystalline thin film by a solution processing process without high temperature treatment. These excellent properties have made them a potential and challenge in the field of lighting.
The methods for realizing white light based on perovskite in the prior art include the following methods:
(1) the perovskite material emitting white light by itself is used, so that the problems of self absorption, phase separation and color instability caused by different emitters can be avoided, but at present, the material can only be used for photoluminescence and cannot be used for electroluminescence;
(2) the perovskite coating is used as a color down-conversion coating of the LED chip, and the following three realization modes are provided:
a. the cold white LED chip and the red perovskite coating;
b. the blue light LED chip + red perovskite coating + green perovskite coating or the blue light LED chip + red phosphor powder + green perovskite coating;
c. ultraviolet LED chip + color filter (red perovskite coating + green perovskite coating + blue perovskite coating).
When using the a, b method, the final device is quite unstable due to the different lifetime decay and stability of each perovskite coating, resulting in white light shift, color change. In addition, the energy is transferred and converted by different substances for many times, resulting in large energy loss. The efficiency of the device is affected and the energy is wasted. While the main bottlenecks using the c method are the low efficiency of the uv LED and the low stability of the blue perovskite.
(3) An electroluminescent perovskite LED comprising three of:
a. a white light LED of all perovskite stack;
b. a white light LED of blue light polymer + yellow light perovskite quantum dots;
c. a white light LED of blue perovskite + orange polymer.
The shortage and relatively low efficiency of blue perovskite materials required for preparing white light using the a, c methods, combined with the generally low lifetime of these materials, has limited their further development.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a perovskite electroluminescence-based white light LED and a preparation method thereof. The invention provides a new idea for realizing the application of perovskite in white electroluminescent light.
The purpose of the invention can be realized by the following technical scheme:
a preparation method of a perovskite electroluminescent white LED comprises the following steps:
(1) cleaning the anode, drying after cleaning, and pretreating the dried anode;
(2) depositing a hole injection layer by adopting a spin coating process, and carrying out heat treatment;
(3) preparing a yellow perovskite solution and a blue light polymer solution, sequentially spin-coating a yellow perovskite layer and a blue light polymer layer, and performing heat treatment processing after each spin-coating layer; the processed yellow perovskite layer and the processed blue polymer layer form an emitting active layer;
(4) transferring the device into a vacuum evaporation bin, and carrying out evaporation on the electron injection layer and the cathode;
(5) the device was encapsulated with epoxy and a glass cover plate.
Specifically, in the step (1), the operation of cleaning and drying the anode is as follows: and (3) sequentially putting the anode into tetrahydrofuran, isopropanol, an alkaline cleaning agent and deionized water for ultrasonic cleaning, wherein the ultrasonic cleaning time in each liquid is 10-20min, and after the ultrasonic cleaning is finished, putting the anode into an oven for drying for later use.
Specifically, in the step (1), the pretreatment is O2-Plasma treatment.
Preferably, the anode is a transparent conductive substrate made of Indium Tin Oxide (ITO), tin dioxide doped zinc oxide, indium gallium zinc oxide or graphene and derivatives thereof.
Specifically, in the step (2), an anode deposited with a hole injection layer is placed on N2Heat treatment is carried out in the glove box, the heat treatment temperature is 130-180 ℃, and the heat treatment time is 10-20 min.
Preferably, the hole injection layer is formed from PEDOT: PSS, NiO or CuSCN.
Specifically, in the step (3), the preparation of the yellow perovskite solution is as follows: dissolving a yellow perovskite material in a polar solvent; the polar solvent includes but is not limited to DMF;
the blue light polymer solution was prepared as follows: dissolving a blue light polymer material in a non-polar solvent or a weak polar solvent; the non-polar and weakly polar solvents include, but are not limited to, p-xylene and chlorobenzene.
The peak value of the generation spectrum of the material of the yellow perovskite light-emitting layer needs to be between 550-590mm, and the peak value of the emission spectrum of the material of the blue polymer light-emitting layer needs to be between 420-480 mm.
Preferably, the yellow perovskite light-emitting layer is made of a three-dimensional perovskite material, a two-dimensional perovskite material or a blend material of a three-dimensional perovskite and a two-dimensional perovskite, such as MAPbBrxI3-x、FAPbBrxI3-xOr CsPbBrxI3-x；
The blue light polymer light emitting layer is made of PFSO, PFO or G0.
Specifically, in the step (3), the heat treatment processing of the yellow perovskite layer is as follows: heating at 50-60 deg.C for 10-15 min;
the heat treatment process for the blue polymer layer was: heating at 50-60 deg.C for 5-10 min;
the heat treatment process can dry the film.
Preferably, the electron injection layer is made of alkali metal, alkaline earth metal or alkali metal compound of distillation type.
Specifically, in the step (4), the thickness of the evaporated electron injection layer is 4-10nm, and the thickness of the evaporated cathode is 100-200 nm.
The perovskite electroluminescence-based white light LED is prepared by the method, and the blue light polymer luminescent layer is simultaneously used as an electron transmission layer, so that the potential barrier of the device is stepped, electrons are transmitted and injected more effectively, and the performance of the device is improved.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides a new idea for realizing white light electroluminescence, namely, the white light LED based on perovskite electroluminescence is prepared by adopting yellow perovskite and blue light polymer, and the electroluminescence spectrum of the white light LED can cover the whole visible light area.
2. The yellow perovskite of the invention has a two-dimensional or three-dimensional structure, and the yellow perovskite layer and the blue polymer layer are respectively used as luminescent layers in a laminating way. And the blue light polymer and the yellow perovskite are jointly used as a light emitting layer, and white light can be emitted at the interface of the blue light polymer and the yellow perovskite in a compounding manner.
3. According to the invention, the blue light polymer which is relatively mature and stable is introduced, so that the blue light polymer not only has the function of emitting blue light, but also serves as an electron transmission layer, and the electron transmission layer is not required to be additionally added, so that the structure and the preparation process of the device are simpler, the use of a blue light perovskite material with resource shortage and relatively low efficiency is avoided.
4. In the invention, the blue light polymer is dissolved in a non-polar solvent, and the yellow perovskite is dissolved in a polar solvent, so that the solvent orthogonal effect is achieved, and the problem of solvent corrosion easily caused by solution processing is solved.
Drawings
The invention is further illustrated by means of the attached drawings, the content of which is not in any way limiting.
Fig. 1 is a schematic structural diagram of a perovskite electroluminescence-based white light LED of the present invention.
Fig. 2 is a schematic structural diagram of the perovskite electroluminescence-based white LED in example 1.
Fig. 3 is a schematic structural diagram of a perovskite electroluminescence-based white LED in example 2.
Fig. 4 is a schematic structural diagram of a perovskite electroluminescence-based white LED in example 3.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
Fig. 1 is a schematic structural diagram of a perovskite electroluminescence-based white light LED of the present invention.
Example 1
As shown in fig. 2, the device structure in this embodiment sequentially includes, from bottom to top: anode (ITO)/hole injection layer (PEDOT: PSS)/yellow perovskite luminescent layer (FAPBR)2.1I0.9) A blue light polymer light emitting layer and electron transport layer (PFSO)/electron injection layer (Ba)/cathode (Ag) with an emission spectrum peak wavelength of 450 nm.
The preparation process comprises the following steps:
(1) placing the ITO substrate in tetrahydrofuran, isopropanol, an alkaline cleaning agent and deionized water in sequence for ultrasonic cleaning, wherein the ultrasonic cleaning time in each liquid is 10min, and after the ultrasonic cleaning is finished, placing the ITO substrate in an oven for drying for later use; the ITO substrate used was subjected to O before spin-coating with a hole injection layer (PEDOT: PSS)2-Plasma treatment to improve the wettability of PEDOT: PSS on ITO;
(2) PSS as a hole injection layer, and then transferring the substrate with the hole injection layer into N2Carrying out heat treatment in a glove box at 150 ℃ for 10 min;
(3) preparation of yellow perovskite solution (solute FAPBBr)2.1I0.9DMF as solvent) and blue-light polymer solution (PFSO as solute and p-xylene as solvent); spin-coating a yellow perovskite layer in a glove box according to the stacking sequence of the device structure, and heating for 10min at the temperature of 60 ℃ after spin-coating; then spin-coating a blue photopolymer layer in a glove box, and heating for 5min at the temperature of 60 ℃ after spin-coating to dry the film;
(4) transferring the device into a vacuum evaporation bin, and performing evaporation on an electron injection layer and a cathode, wherein the thickness of the evaporated electron injection layer (Ba) is 7nm, and the thickness of the evaporated cathode (Ag) is 150 nm;
(5) after the silver electrode is evaporated, the device is encapsulated with epoxy resin and a glass cover plate.
Example 2
As shown in fig. 3, the device structure in this embodiment is as follows from top to bottom: anode (graphene)/hole injection layer (NiO)/yellow perovskite luminescent layer (MAPbBr) with emission spectrum peak wavelength of 580nm1.8I1.2) Blue light polymer luminescent layer and electron transport layer (PFO)/electron injection Layer (LiF)/cathode (Al) with peak wavelength of emission spectrum of 440 nm.
The preparation process comprises the following steps:
(1) sequentially placing the graphene substrate in tetrahydrofuran, isopropanol, an alkaline cleaning agent and deionized water for ultrasonic cleaning, wherein the ultrasonic cleaning time in each liquid is 15min, and after the ultrasonic cleaning is finished, placing the substrate in an oven for drying for later use; subjecting the graphene substrate to O before spin-coating a hole injection layer (NiO)2Plasma treatment to improve the wettability of NiO on graphene.
(2) Depositing a layer of NiO with the thickness of 35nm as a hole injection layer by adopting a spin coating process, and then transferring the substrate deposited with the hole injection layer into N2Carrying out heat treatment in a glove box at 150 ℃ for 10 min;
(3) preparation of yellow perovskite solution (solute MAPbBr)1.8I1.2DMF as solvent), and blue-light polymer solution (PFO as solute and chlorobenzene as solvent); spin-coating a yellow perovskite layer in a glove box according to the stacking sequence of the device structure, and heating for 10min at the temperature of 60 ℃ after spin-coating; then spin-coating blue photopolymer PFO in a glove box, heating for 5min at the temperature of 60 ℃ after spin-coating, and drying the film;
(4) transferring the device into a vacuum evaporation bin, and carrying out evaporation on an electron injection layer and a cathode, wherein the thickness of the evaporated electron injection Layer (LiF) is 4nm, and the thickness of the evaporated cathode (Al) is 100 nm;
(5) after the aluminum electrode is evaporated, the device is encapsulated with epoxy resin and a glass cover plate.
Example 3
As shown in fig. 4, the device structure of this embodiment is, in order from top to bottom: anode (ITO)/hole injection layer (CuSCN)/yellow perovskite luminescent layer (CsPbBr) with peak wavelength of emission spectrum of 566nm2.1I0.9) Blue light polymer light-emitting layer and electron transport layer (G0)/electron injection layer (Ca)/cathode (Al) with peak wavelength of emission spectrum of 455 nm.
The preparation process comprises the following steps:
(1) placing the ITO substrate in tetrahydrofuran, isopropanol, an alkaline cleaning agent and deionized water in sequence for ultrasonic cleaning, wherein the ultrasonic cleaning time in each liquid is 15min, and after the ultrasonic cleaning is finished, placing the ITO substrate in an oven for drying for later use; before spin-coating the hole injection layer (CuSCN), the ITO substrate used was subjected to O2Plasma treatment to improve the wettability of NiO on graphene.
(2) Depositing a layer of CuSCN with the thickness of 40nm as a hole injection layer by adopting a spin coating process, and then transferring the substrate deposited with the hole injection layer into N2Carrying out heat treatment in a glove box at 150 ℃ for 10 min;
(3) solution for preparing yellow perovskite (solute CsPbBr)2.1I0.9DMF as solvent), and a solution of blue-light polymer (G0 as solute and p-xylene as solvent); spin-coating a yellow perovskite layer (CsPbBr) in a glove box in the order of stacking the device structures2.1I0.9) After spin coating, heating for 10min at the temperature of 60 ℃; then spin-coating blue photopolymer (G0) in glove box, heating at 60 deg.C for 5min to dry the film;
(4) transferring the device into a vacuum evaporation bin, and carrying out evaporation on an electron injection layer and a cathode, wherein the thickness of the evaporated electron injection layer (Ca) is 6nm, and the thickness of the evaporated cathode (Al) is 100 nm;
(5) after the aluminum electrode is evaporated, the device is encapsulated with epoxy resin and a glass cover plate.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. A perovskite electroluminescent white light LED preparation method, wherein use the lamination way to make yellow light perovskite layer and blue light polymer layer as the luminescent layer separately, and blue light polymer and yellow light perovskite regard as the luminescent layer jointly and can compound and send out the white light at the interface of blue light polymer and yellow light perovskite, including the step:
(1) cleaning the anode, drying after cleaning, and pretreating the dried anode;
(2) depositing a hole injection layer by adopting a spin coating process, and carrying out heat treatment;
(3) preparing a yellow perovskite solution and a blue light polymer solution, sequentially spin-coating a yellow perovskite layer and a blue light polymer layer, and performing heat treatment processing after each spin-coating layer; the processed yellow perovskite layer and the processed blue polymer layer form an emitting active layer;
(4) transferring the device into a vacuum evaporation bin, and carrying out evaporation on the electron injection layer and the cathode;
(5) the device was encapsulated with epoxy and a glass cover plate.
2. The method of claim 1, wherein in the step (1), the anode cleaning and drying operation comprises: sequentially putting the anode into tetrahydrofuran, isopropanol, an alkaline cleaning agent and deionized water for ultrasonic cleaning, wherein the ultrasonic cleaning time in each liquid is 10-20min, and after the ultrasonic cleaning is finished, putting the anode into an oven for drying for later use; the pretreatment is O2-Plasma treatment.
3. The method according to claim 1, wherein the anode is a transparent conductive substrate made of indium tin oxide, tin dioxide doped zinc oxide, indium gallium zinc oxide or graphene and derivatives thereof.
4. The method of claim 1, wherein in the step (2), the anode deposited with the hole injection layer is placed in N2Heat treatment is carried out in the glove box, the heat treatment temperature is 130-180 ℃, and the heat treatment time is 10-20 min.
5. The method of claim 1, wherein the hole injection layer is formed from PEDOT: PSS, NiO or CuSCN.
6. The method according to claim 1, wherein in step (3), a yellow perovskite solution is prepared: dissolving a yellow perovskite material in a polar solvent; the polar solvent includes but is not limited to DMF;
preparation of blue-light polymer solution: dissolving a blue light polymer material in a non-polar solvent or a weak polar solvent; the non-polar and weakly polar solvents include, but are not limited to, p-xylene and chlorobenzene;
the peak value of the generation spectrum of the material of the yellow perovskite light-emitting layer needs to be between 550-590mm, and the peak value of the emission spectrum of the material of the blue polymer light-emitting layer needs to be between 420-480 mm.
7. The method according to claim 1, wherein in step (3), the heat treatment process for the yellow perovskite layer is: heating at 50-60 deg.C for 10-15 min;
the heat treatment process for the blue polymer layer was: heating at 50-60 deg.C for 5-10 min.
8. The method according to claim 1, characterized in that the electron injection layer is made of alkali metal, alkaline earth metal or alkali metal compound of the distillation type.
9. The method as claimed in claim 1, wherein in step (4), the thickness of the evaporated electron injection layer is 4-10nm, and the thickness of the evaporated cathode is 100-200 nm.
10. A perovskite electroluminescence based white LED prepared by the method of any one of claims 1 to 9; the blue photopolymer layer also acts as an electron transport layer.
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| CN105374937A (en) * | 2015-10-19 | 2016-03-02 | 浙江大学 | Perovskite MIS structure electroluminescent device and preparation method thereof |
| CN109346616A (en) * | 2018-10-11 | 2019-02-15 | 电子科技大学 | A kind of white light Ca-Ti ore type electroluminescent device and preparation method |
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| CN105374937A (en) * | 2015-10-19 | 2016-03-02 | 浙江大学 | Perovskite MIS structure electroluminescent device and preparation method thereof |
| CN109346616A (en) * | 2018-10-11 | 2019-02-15 | 电子科技大学 | A kind of white light Ca-Ti ore type electroluminescent device and preparation method |
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