CN113611807B - Blue-light perovskite light-emitting diode and preparation method thereof - Google Patents

Blue-light perovskite light-emitting diode and preparation method thereof Download PDF

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CN113611807B
CN113611807B CN202110788114.7A CN202110788114A CN113611807B CN 113611807 B CN113611807 B CN 113611807B CN 202110788114 A CN202110788114 A CN 202110788114A CN 113611807 B CN113611807 B CN 113611807B
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perovskite
light
layer
precursor solution
emitting diode
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CN113611807A (en
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李贵君
罗忠明
刘保星
郑婷
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Shenzhen University
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    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10KORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00Organic light-emitting devices
    • H10K50/10OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • HELECTRICITY
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Abstract

The invention discloses a blue light perovskite light-emitting diode and a preparation method thereof, the structure of the blue light perovskite light-emitting diode sequentially comprises a substrate, an anode, a hole transport layer, a light-emitting layer, a passivation layer, an electron transport layer, an electron injection layer and a cathode from bottom to top, wherein the light-emitting layer is a perovskite thin film prepared from a perovskite precursor solution; when the blue-light perovskite light-emitting diode is prepared, a perovskite precursor solution added with a thiocyanate additive is used for preparing a perovskite film, so that the film appearance of a light-emitting layer is adjusted through the thiocyanate additive; after the perovskite thin film is prepared, the perovskite thin film is passivated so as to improve the performance of the perovskite thin film. The invention further reduces the surface defects of the film and improves the light-emitting performance of the blue-light perovskite light-emitting diode by using the perovskite film prepared by additive engineering of the perovskite precursor solution added with thiocyanate additives and surface passivation treatment.

Description

Blue-light perovskite light-emitting diode and preparation method thereof
Technical Field
The invention relates to the technical field of photoelectronic device preparation, in particular to a blue light perovskite light emitting diode and a preparation method thereof.
Background
The metal halide perovskite is a new semiconductor material with excellent photoelectric properties, has the characteristics of high electron/hole mobility, high photoluminescence quantum yield, high color purity, easiness in color matching and the like, and provides a brand-new opportunity for high-definition display and solid-state illumination. In display terms, perovskite light emitting diodes (PeLEDs) have the same advantages as Organic Light Emitting Diodes (OLEDs), and further compensate for the disadvantages of poor color purity and high cost of OLEDs. PeLEDs have evolved rapidly in recent years, with External Quantum Efficiencies (EQE) of near-infrared, red and green perovskite light emitting devices all exceeding 20%, but the performance of blue PeLEDs is relatively poor.
Adjusting the morphology of the perovskite thin film through additive engineering is one of effective methods for improving the performance of the PelLEDs. Some additives form a perovskite mesophase in the precursor solution due to coordination or chelation of the lone electrons of the oxygen, sulfur, or nitrogen atoms with the lead ions. The mesophase helps to regulate the crystallization kinetics of the perovskite film, making the film morphology better. The appropriate additive can effectively reduce the defects of the perovskite thin film and reduce the loss of composite photons. Therefore, the luminous performance of the PeLEDs can be improved by using additive engineering. Surface passivation treatment processes are also common strategies to improve PeLEDs performance. The perovskite thin film prepared by the solution method still has residual solvent, unconverted precursor and defect sites. The presence of the above-mentioned problems inevitably limits the performance of PeLEDs.
The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.
Disclosure of Invention
The invention mainly aims to provide a blue perovskite light-emitting diode and a preparation method thereof, and aims to solve the technical problem of poor performance of blue Peleds.
In order to achieve the purpose, the invention provides a blue perovskite light emitting diode, which comprises a substrate, an anode, a hole transport layer, a light emitting layer, a passivation layer, an electron transport layer, an electron injection layer and a cathode from bottom to top in sequence, wherein the light emitting layer is a perovskite thin film prepared from a perovskite precursor solution;
when the blue-light perovskite light-emitting diode is prepared, the perovskite thin film is prepared through a perovskite precursor solution added with a thiocyanate additive, and the appearance of the thin film of the light-emitting layer is adjusted through the thiocyanate additive;
after the perovskite thin film is prepared, the perovskite thin film is passivated so as to improve the performance of the perovskite thin film.
Optionally, the solution added with the thiocyanate additive is a perovskite precursor solution, and a passivation layer precursor solution is spin-coated on the perovskite thin film to perform passivation treatment on the perovskite thin film;
dissolving cesium bromide, lead bromide, a large-group organic halide and a thiocyanate additive in a dimethyl sulfoxide solvent to prepare a perovskite precursor solution;
and dissolving the passivation layer material in a chlorobenzene solvent to prepare a passivation layer precursor solution.
Optionally, the perovskite precursor solution has a formula of components:
cesium bromide CsBr:0.1-0.3mol/L;
lead bromide PbBr 2 :0.1-0.3mol/L;
Phenethyl amine chloride PEACl:0.1-0.3mol/L;
guanidine bromide GABr:0.1-0.3mol/L;
thiocyanate salt: 0.05-0.1mol/L.
Optionally, the thiocyanate additive comprises ammonium thiocyanate additive, guanidine thiocyanate additive, ammonium thiocyanate additive or additive with guanidine thiocyanate and ammonium thiocyanate, and the passivation layer material comprises tri-n-octylphosphine oxide or triphenylphosphine oxide.
Optionally, the thicknesses of the respective layer structures of the blue perovskite light emitting diode are respectively as follows:
the thickness of the anode: 10-300nm;
thickness of the hole transport layer: 20-100nm;
thickness of the passivation layer: 20-100nm;
thickness of the electron transport layer: 20-100nm;
thickness of the electron injection layer: 0.5-3nm;
thickness of the cathode: 50-200nm.
Optionally, the substrate is a glass substrate;
the anode is indium tin oxide transparent conductive glass or a flexible transparent electrode;
the hole transport layer is one or more of PEDOT, PSS, PVK or Poly-TPD, wherein the PEDOT, PSS (Poly (3, 4-ethylenedioxythiophene) -polystyrene sulfonic acid), PVK (polyvinyl carbazole) and Poly-TPD (Poly [ bis (4-phenyl) (4-butylphenyl) amine ]);
the luminescent layer consists of perovskite, large-group organic halide and thiocyanate additive;
the passivation layer is one or more of tri-n-octyl phosphine oxide or triphenylphosphine oxide;
the electron transport layer is one or more of TPBi, POT2T or TmPyPB, wherein the TPBi is 1,3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene, the POT2T is (1, 3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene), and the TmPyPB is (2, 4, 6-tri [3- (diphenylphosphinoxy) phenyl ] -1,3, 5-triazole) (4, 6-bis (3, 5-di (3-pyridine) phenyl) -2-methylpyrimidine);
the electron injection layer is lithium fluoride or 8-hydroxyquinoline-lithium;
the cathode is aluminum or silver.
The invention also provides a preparation method of the blue perovskite light-emitting diode, which is used for preparing any one of the blue perovskite light-emitting diodes, and the preparation method of the blue perovskite light-emitting diode comprises the following steps:
providing an ITO glass substrate, and carrying out pattern design on the ITO glass substrate by utilizing a laser etching process to obtain a first prefabricated object;
sequentially carrying out ultrasonic cleaning on the first prefabricated part by using deionized water, alkali liquor, isopropanol solution and ethanol solution, and drying the cleaned first prefabricated part to obtain a second prefabricated part;
carrying out UV ozone pretreatment on the second prefabricated part to obtain a third prefabricated part;
spin-coating a hole transport layer precursor solution on the third prefabricated object, and performing annealing treatment to obtain a hole transport layer on the ITO glass substrate;
spin-coating the perovskite precursor solution on the hole transport layer, and carrying out annealing treatment to obtain a light-emitting layer;
spin-coating a passivation layer precursor solution on the light-emitting layer to obtain a passivation layer;
and sequentially evaporating an electron transmission layer, an electron injection layer and a cathode on the passivation layer by a vacuum thermal evaporation method to obtain the blue-light perovskite light-emitting diode.
Optionally, before the step of spin coating a hole transport layer precursor solution on the third preform and performing an annealing process to obtain a hole transport layer on the ITO glass substrate, the method further includes:
mixing a PEDOT (4083) solution and an ethanolamine solution to prepare a hole transport layer precursor solution;
wherein the volume ratio of the PEDOT: PSS (4083) solution to the ethanolamine solution is 1000.
Optionally, the cleaning time period corresponding to ultrasonic cleaning of the first preform is 10-20min, and the treatment time period corresponding to UV ozone pretreatment of the second preform is 10-20min.
Optionally, the preparation method of the blue perovskite light emitting diode further comprises:
spin-coating the hole transport layer precursor solution on the third prefabricated object at a first preset rotation speed for a first spin-coating time, and annealing at a first preset temperature for a first preset time to obtain a hole transport layer on the ITO glass substrate;
spin-coating the perovskite precursor solution on the hole transport layer at a second preset rotation speed for a second spin-coating time, and annealing at a second preset temperature for a second preset time to obtain a light-emitting layer;
and spin-coating the passivation layer precursor solution on the light-emitting layer at a third preset rotation speed for a third spin-coating time to obtain the passivation layer.
The invention provides a blue perovskite light-emitting diode, which structurally comprises a substrate, an anode, a hole transport layer, a light-emitting layer, a passivation layer, an electron transport layer, an electron injection layer and a cathode from bottom to top in sequence, wherein the light-emitting layer is a perovskite thin film prepared from a perovskite precursor solution; when the blue-light perovskite light-emitting diode is prepared, the perovskite thin film is prepared through a perovskite precursor solution added with a thiocyanate additive, and the appearance of the thin film of the light-emitting layer is adjusted through the thiocyanate additive; after the perovskite thin film is prepared, the perovskite thin film is passivated so as to improve the performance of the perovskite thin film. According to the invention, the perovskite thin film is prepared based on the additive engineering of the perovskite precursor solution added with the thiocyanate additive, and the surface of the thin film between the perovskite luminescent layer and the electron transport layer is passivated by utilizing surface passivation treatment, so that the surface defects of the thin film are reduced, the appearance of the thin film of the electron transport layer is improved, the performance of the blue perovskite light-emitting diode is further improved by effectively reducing non-radiative recombination, and the blue perovskite light-emitting diode with better luminescent performance and higher external quantum efficiency can be prepared.
Drawings
FIG. 1 is a schematic diagram of a blue perovskite light emitting diode of the present invention;
FIG. 2 is a schematic flow chart of a first embodiment of a method for manufacturing a blue perovskite light emitting diode according to the present invention;
FIG. 3 is a CIE color coordinate diagram of a blue perovskite light emitting diode prepared by the method for preparing the blue perovskite light emitting diode of the invention;
FIG. 4 is a graph of external quantum efficiency and current density of a blue perovskite light emitting diode correspondingly prepared in a first preparation process based on a perovskite precursor solution according to the present invention;
FIG. 5 shows the electroluminescence spectra of blue perovskite light emitting diodes correspondingly prepared in a first perovskite precursor solution-based preparation process under different bias voltages;
FIG. 6 is a graph of external quantum efficiency and current density of a blue perovskite light emitting diode correspondingly prepared in a second preparation process based on a perovskite precursor solution according to the present invention;
FIG. 7 shows the electroluminescence spectra of a blue perovskite LED under different bias voltages, correspondingly prepared in a second perovskite precursor solution-based preparation process according to the present invention;
FIG. 8 is a graph of luminance and voltage of a blue perovskite light emitting diode correspondingly fabricated in a second fabrication process based on a perovskite precursor solution according to the present invention;
FIG. 9 is a graph of external quantum efficiency and current density of a blue perovskite light emitting diode correspondingly prepared in a third preparation process based on a perovskite precursor solution according to the present invention;
fig. 10 shows the electroluminescence spectra of the blue-light perovskite light emitting diode correspondingly prepared by the third preparation process based on the perovskite precursor solution according to the present invention under different bias voltages.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
The invention provides a blue light perovskite light emitting diode, which refers to a structural schematic diagram of the blue light perovskite light emitting diode shown in figure 1, and the structure of the blue light perovskite light emitting diode sequentially comprises a substrate, an anode, a hole transport layer, a light emitting layer, a passivation layer, an electron transport layer, an electron injection layer and a cathode from bottom to top, wherein the light emitting layer is a perovskite thin film prepared from a perovskite precursor solution;
when the blue-light perovskite light-emitting diode is prepared, the perovskite thin film is prepared through a perovskite precursor solution added with a thiocyanate additive, and the appearance of the thin film of the light-emitting layer is adjusted through the thiocyanate additive;
after the perovskite thin film is prepared, the perovskite thin film is passivated so as to improve the performance of the perovskite thin film.
In this example, thiocyanate (SCN) - ) The anion is a stable halogen-like anion with an ionic radius almost the same as that of iodide, thiocyanate (SCN) - ) The introduction of anions can reduce the vacancy of the crystal structure of the perovskite thin film, the vacancy of the crystal structure in the perovskite thin film is filled, the crystal structure of the perovskite thin film is more stable, the defect of the perovskite thin film is reduced, the performance of the perovskite thin film is improved, and the luminescence performance of the luminescent layer is optimizedAnd, thiocyanate radical (SCN) - ) Can form strong ion interaction with adjacent cation and reduce the film defect to form strong ion interaction through the vacancy that reduces perovskite thin film crystal structure and with adjacent cation, reduce the defect of perovskite thin film, promote the performance of perovskite thin film, promote blue light perovskite light emitting diode's luminous performance.
In addition, the addition of the thiocyanate additive improves the stability of the crystal structure of the perovskite thin film, is beneficial to adjusting the crystallization kinetics of the perovskite thin film and enables the form of the perovskite thin film to be better. The addition of the thiocyanate obviously improves the flatness and the perovskite crystallinity of the perovskite thin film, and is beneficial to reducing the defect density at a crystal boundary, thereby inhibiting photoluminescence quenching, avoiding non-radiative recombination loss increased by ion defects in an interface and the perovskite thin film, reducing the loss of composite photons and improving the photoelectric performance of the blue-light perovskite light-emitting diode.
The perovskite thin film prepared by the solution method still has residual solvent, unconverted precursor and insufficient smoothness of the surface of the perovskite thin film caused by defect points, and the performance of the blue perovskite light-emitting diode is inevitably limited due to the problems, so that the light-emitting performance of the blue perovskite light-emitting diode can be further improved by passivating the light-emitting layer.
Further, a passivation layer precursor solution is spin-coated on the perovskite thin film to perform passivation treatment on the perovskite thin film, namely the prepared luminescent layer is spin-coated with the passivation layer precursor solution to perform passivation treatment on the luminescent layer.
The preparation method of the perovskite precursor solution comprises the following steps: cesium bromide, lead bromide, a large-group organic halide and a thiocyanate additive are dissolved in a dimethyl sulfoxide solvent to prepare a perovskite precursor solution. The perovskite precursor solution is used for preparing a perovskite thin film, namely a luminescent layer.
The preparation method of the passivation layer precursor solution comprises the following steps: and dissolving the passivation layer material in a chlorobenzene solvent to prepare a passivation layer precursor solution.
Further, the thiocyanate additive can be any one of ammonium thiocyanate additive, guanidine thiocyanate additive, ammonium thiocyanate additive or additive added with guanidine thiocyanate and ammonium thiocyanate, and the passivation layer material can be any one of tri-n-octyl phosphine oxide or triphenylphosphine oxide.
In this example, when the passivation material used for passivation is TOPO (short for trioctylphosphine oxide), the perovskite thin film is passivated by a solution prepared from TOPO, which is a highly branched blocking ligand with strong steric effect and is generally used as a blocking ligand for conventional II-VI, III-V and IV-VI perovskite quantum dots.
The principle of passivating the defects of the perovskite thin film by TOPO is based on the fact that trioctyl groups of TOPO molecules are located at three vertexes of a plane, and the only oxygen atom is located at the fourth vertex, so that the perovskite thin film is highly branched in structure and stable in molecular structure, and in addition, the perovskite thin film has relatively strong coordination capacity of P = O groups, and the crystal structure of the perovskite thin film can be more stable. TOPO may also work in concert with the surface of the perovskite crystals to provide more complete surface passivation of the perovskite crystals, further reducing non-radiative recombination on the perovskite surface or grain boundaries.
Further, the perovskite precursor solution comprises the following components:
cesium bromide CsBr:0.1-0.3mol/L;
lead bromide PbBr2:0.1-0.3mol/L;
phenethyl amine chloride PEACl:0.1-0.3mol/L;
guanidine bromide GABr:0.1-0.3mol/L;
thiocyanate salt: 0.05-0.1mol/L.
Further, the thickness of each layer structure of the blue perovskite light emitting diode is as follows:
anode: 10-300nm;
hole transport layer: 20-100nm;
passivation layer: 20-100nm;
electron transport layer: 20-100nm;
electron injection layer: 0.5-3nm;
cathode: 50-200nm.
Further, the substrate may be a glass substrate; the anode can be indium tin oxide transparent conductive glass or a flexible transparent electrode; the hole transport layer can be one or more of PEDOT (Poly (3, 4-ethylenedioxythiophene) -polystyrene sulfonic acid), PVK (polyvinylcarbazole) and Poly-TPD (Poly [ bis (4-phenyl) (4-butylphenyl) amine) ]; the luminescent layer consists of perovskite, large-group organic halide and thiocyanate additive; the passivation layer can be one or more of tri-n-octyl phosphine oxide or triphenylphosphine oxide; the electron transport layer can be one or more of TPBi, POT2T or TmPyPB, wherein TPBi is 1,3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene, POT2T can be (1, 3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene), tmPyPB can be (2, 4, 6-tri [3- (diphenylphosphinoxy) phenyl ] -1,3, 5-triazole) (4, 6-bis (3, 5-di (3-pyridine) phenyl) -2-methylpyrimidine); the electron injection layer can be lithium fluoride or 8-hydroxyquinoline-lithium; the cathode may be aluminum or silver.
The invention also provides a preparation method of the blue perovskite light emitting diode, and referring to fig. 2, fig. 2 is a schematic flow chart of a first embodiment of the preparation method of the blue perovskite light emitting diode.
In this embodiment, the preparation method of the blue perovskite light emitting diode includes the following steps:
step S10, providing an ITO glass substrate, and carrying out pattern design on the ITO glass substrate by utilizing a laser etching process to obtain a first prefabricated object;
in this embodiment, starting with the preparation of the blue perovskite light emitting diode, an ITO glass substrate is provided to prepare the blue perovskite light emitting diode according to the ITO glass substrate; and carrying out pattern design on the ITO glass substrate by utilizing a laser etching process to obtain a first prefabricated object. Wherein, the ITO is indium tin oxide, the ITO glass substrate is a glass substrate covered with ITO (indium tin oxide), namely the glass substrate is covered with ITO, the glass substrate is used as a substrate of the blue light perovskite light emitting diode, and the ITO is used as an anode of the blue light perovskite light emitting diode; the first preform is an ITO glass substrate after designing a pattern.
S20, sequentially carrying out ultrasonic cleaning on the first prefabricated object by using deionized water, alkali liquor, an isopropanol solution and an ethanol solution, and drying the cleaned first prefabricated object to obtain a second prefabricated object;
step S30, carrying out UV ozone pretreatment on the second prefabricated part to obtain a third prefabricated part;
in this embodiment, after the ITO glass substrate is subjected to pattern design, the first preform (i.e., the patterned ITO glass substrate) is sequentially subjected to ultrasonic cleaning using deionized water, alkali solution, isopropanol solution, and ethanol solution, respectively. After ultrasonic cleaning, the cleaned first preform is dried to obtain a second preform. Wherein the step of drying the cleaned first preform comprises: drying the fabric firstly and then putting the fabric into a drying box for drying. The second preform is the cleaned and dried first preform. And after the second prefabricated part is obtained, carrying out UV ozone pretreatment on the second prefabricated part to obtain a third prefabricated part, wherein the third prefabricated part is the second prefabricated part subjected to UV ozone pretreatment.
Further, the cleaning time period corresponding to ultrasonic cleaning of the first prefabricated part is 10-20min, and the treatment time period corresponding to UV ozone pretreatment of the second prefabricated part is 10-20min.
Step S40, spin-coating the hole transport layer precursor solution on a third prefabricated object, and carrying out annealing treatment to obtain a hole transport layer on the ITO glass substrate;
in this embodiment, the hole transport layer precursor solution is spin-coated on the ITO glass substrate processed in step S30, and then the third preform spin-coated with the hole transport layer precursor solution is annealed to obtain the hole transport layer, so as to prepare the hole transport layer on the ITO glass substrate, that is, the hole transport layer is on the ITO glass substrate. And further spin-coating the hole transport layer precursor solution on the third prefabricated object at a first preset rotation speed for a first spin-coating time, and annealing at a first preset temperature for a first preset time to obtain the hole transport layer on the ITO glass substrate. Wherein the first preset rotating speed is 3000-7000rpm, the first spin coating time is 30-60s, the first preset time is annealing time, the first preset time is 5-30min, the first preset temperature is annealing temperature, and the first preset temperature is 130-170 ℃.
Further, before the hole transport layer is prepared, a hole transport layer precursor solution is prepared, and the preparation process of the hole transport layer precursor solution is as follows: and (2) mixing the PEDOT: PSS (4083) solution with an ethanolamine solution according to a volume ratio of 1000.
S50, spin-coating the perovskite precursor solution on the hole transport layer, and carrying out annealing treatment to obtain a light-emitting layer;
in this embodiment, after the hole transport layer is prepared, a perovskite precursor solution prepared in advance is spin-coated on the hole transport layer, and then the hole transport layer coated with the perovskite precursor solution is annealed to obtain a perovskite light-emitting layer, that is, a light-emitting layer, and the obtained light-emitting layer is on the hole transport layer. And further, spin-coating the perovskite precursor solution on the hole transport layer at a second preset rotation speed for a second spin-coating time, and annealing at a second preset temperature for a second preset time to obtain the light-emitting layer. Wherein the second preset rotating speed is 3000-7000rpm, the second spin coating time is 30-60s, the second preset time is annealing time, the second preset time is 5-30min, the second preset temperature is annealing temperature, and the second preset temperature is 80-100 ℃.
Step S60, spin-coating a passivation layer precursor solution on the light-emitting layer to obtain a passivation layer;
in this embodiment, a passivation layer is obtained by spin-coating a previously prepared passivation layer precursor solution on a perovskite light emitting layer without annealing, and the obtained passivation layer is on the light emitting layer. Further, before the passivation layer is prepared, a passivation layer precursor solution is prepared, and the preparation process of the passivation layer precursor solution is as follows: dissolving the passivation layer material TOPO in a CB solvent to obtain a passivation layer precursor solution with the solubility of 0.8 mg/mL. Wherein TOPO is tri-n-octyl phosphine oxide, and CB is chlorobenzene.
And further, spin-coating the passivation layer precursor solution on the light-emitting layer at a rotation speed of 5000rpm for 60s to obtain the passivation layer.
And S70, sequentially evaporating an electron transmission layer, an electron injection layer and a cathode on the passivation layer by a vacuum thermal evaporation method to obtain the blue-light perovskite light-emitting diode.
Referring to the structural schematic diagram of the blue perovskite light emitting diode shown in fig. 2, the blue perovskite light emitting diode is prepared through the preparation process of S10-S70, the substrate, the anode, the hole transport layer, the light emitting layer, the passivation layer, the electron transport layer, the electron injection layer and the cathode are sequentially arranged from bottom to top, and the color coordinate corresponding to the light emitted by the prepared blue perovskite light emitting diode is (0.0726, 0.2905), referring to the CIE color coordinate diagram of the blue perovskite light emitting diode shown in fig. 3.
In this embodiment, after the passivation layer is obtained, the electron transport layer, the electron injection layer, and the cathode are sequentially evaporated on the passivation layer by a vacuum thermal evaporation method, so as to finally obtain the blue perovskite light emitting diode. That is, on the passivation layer, there are an electron transport layer, an electron injection layer, and a cathode in this order. Further, an electron transport layer with the thickness of 48.5nm, an electron injection layer with the thickness of 1nm and a cathode with the thickness of 120nm are sequentially evaporated on the passivation layer by a vacuum thermal evaporation method, and the blue perovskite light-emitting diode is obtained. Wherein the prepared electron transport layer is TPBi which is 1,3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene; the prepared electron injection layer is LiF, and LiF is lithium fluoride; the prepared cathode is Al, and the Al is aluminum.
According to the preparation method of the blue-light perovskite light emitting diode, the ITO glass substrate is provided, and the pattern design is carried out on the ITO glass substrate by utilizing the laser etching process, so that the first prefabricated object is obtained; sequentially carrying out ultrasonic cleaning on the first prefabricated part by using deionized water, alkali liquor, isopropanol solution and ethanol solution, and drying the cleaned first prefabricated part to obtain a second prefabricated part; carrying out UV ozone pretreatment on the second prefabricated part to obtain a third prefabricated part; spin-coating a hole transport layer precursor solution on the third prefabricated object, and carrying out annealing treatment to obtain a hole transport layer on the ITO glass substrate; spin-coating the perovskite precursor solution on the hole transport layer, and carrying out annealing treatment to obtain a light-emitting layer; spin-coating a passivation layer precursor solution on the light-emitting layer to obtain a passivation layer; and sequentially evaporating an electron transmission layer, an electron injection layer and a cathode on the passivation layer by a vacuum thermal evaporation method to obtain the blue-light perovskite light-emitting diode. The blue perovskite light-emitting diode is obtained through the preparation process, and the structure of the prepared blue perovskite light-emitting diode sequentially comprises a substrate, an anode, a hole transport layer, a light-emitting layer, a passivation layer, an electron transport layer, an electron injection layer and a cathode from bottom to top. In the embodiment, the perovskite thin film prepared based on the additive engineering and the surface of the thin film between the perovskite luminescent layer and the electron transport layer are passivated by utilizing surface passivation treatment, so that the surface defects of the thin film are reduced, the appearance of the thin film of the electron transport layer is improved, the performance of the blue perovskite light emitting diode is effectively improved by non-radiative recombination, and the blue perovskite light emitting diode with higher external quantum efficiency can be prepared.
Based on the first embodiment, a second embodiment of the method for manufacturing a blue perovskite light emitting diode according to the present invention is provided, in this embodiment, before step S50, the following process for preparing perovskite precursor solutions of three different thiocyanate additives includes:
step A1, cesium bromide, lead bromide, a large-group organic halide and a methyl ammonium thiocyanate additive are dissolved in a dimethyl sulfoxide solvent to obtain the perovskite precursor solution.
In this embodiment, before the light-emitting layer is prepared, a perovskite precursor solution is prepared, and there are various methods for preparing the perovskite precursor solution, and different perovskite precursor solutions can be prepared from different components. This example proposes a first preparation process of a perovskite precursor solution, which is: cesium bromide (CsBr) and lead bromide (PbBr) 2 ) Large baseDissolving organic halide and ammonium methyl thiocyanate (MASCN) additive in dimethyl sulfoxide (DMSO) solvent, and mixing to obtain perovskite precursor solution.
Further, in the first preparation process of the perovskite precursor solution, the perovskite precursor solution prepared by the first preparation process may have a formula of each component:
CsBr:0.2mol/L;
PbBr 2 :0.2mol/L;
PEACl:0.2mol/L;
GABr:0.1mol/L;
MASCN:0.018mol/L。
in the embodiment, based on additive engineering, a thiocyanate additive is introduced into a perovskite precursor solution to adjust the crystallization kinetics of the perovskite thin film, so that a perovskite luminescent layer with a better thin film form is obtained. In addition, the introduction of the additive effectively reduces the defects of the perovskite thin film and the loss of composite photons, and can obviously improve the light emitting performance of the blue perovskite light emitting diode.
Referring to the graphs of external quantum efficiency and current density of the blue perovskite light emitting diode correspondingly prepared by the first preparation process based on the perovskite precursor solution shown in fig. 4, compared with the reference device without adding the ammonium thiocyanate (MASCN) additive and without performing the passivation treatment on the tri-n-octylphosphine oxide (TOPO), it can be seen that the addition of the MASCN additive in this embodiment raises the external quantum efficiency of the device to 8.91%, and the external quantum efficiency is raised from 8.91% to 10.62% after performing the surface passivation treatment on the TOPO.
Referring to the electroluminescence spectra of the blue perovskite light emitting diode prepared by the first preparation process based on the perovskite precursor solution shown in fig. 5 under different bias voltages, it can be seen that the device subjected to the MASCN addition and the TOPO passivation treatment exhibits very good spectral stability, and the spectrum does not shift under the bias voltage change of 3V to 6V.
Further, before step S50, the method further includes:
and A2, dissolving cesium bromide, lead bromide, a large-group organic halide and a guanidine thiocyanate additive in a dimethyl sulfoxide solvent to obtain the perovskite precursor solution.
In this embodiment, the present embodiment proposes a second preparation process of the perovskite precursor solution, where the second preparation process of the perovskite precursor solution is as follows: cesium bromide (CsBr) and lead bromide (PbBr) 2 ) And dissolving the large-group organic halide and guanidine thiocyanate (GuSCN) additive in a dimethyl sulfoxide (DMSO) solvent, and fully mixing to obtain a perovskite precursor solution.
Further, in the second preparation process of the perovskite precursor solution, the perovskite precursor solution prepared by the second preparation process may have the following formula:
CsBr:0.2mol/L;
PbBr 2 :0.2mol/L;
PEACl:0.2mol/L;
GABr:0.1mol/L;
GuSCN:0.0135mol/L。
referring to the graphs of external quantum efficiency and current density of the blue perovskite light emitting diode correspondingly prepared by the second preparation process based on the perovskite precursor solution shown in fig. 6, compared with the reference device without adding guanidine thiocyanate (GuSCN) additive and without TOPO passivation treatment, it can be seen that the addition of the GuSCN additive in the present embodiment raises the external quantum efficiency of the device to 9.39%, and the external quantum efficiency is raised from 9.39% to 11.80% after TOPO surface passivation treatment.
Referring to the electroluminescence spectra of the blue perovskite light emitting diode prepared by the second preparation process based on the perovskite precursor solution shown in fig. 7 under different bias voltages, it can be seen that the device subjected to the addition of GuSCN and the TOPO passivation treatment has better spectral stability, and the spectrum only shifts by 2nm under the bias voltage change of 6V.
Referring to the graphs of the emission luminance and voltage of the blue perovskite light emitting diode correspondingly fabricated based on the second fabrication process of the perovskite precursor solution shown in fig. 8, compared to the reference device without the GuSCN additive,the addition of GuSCN directly improves the luminous brightness of the device to 4019cd/m 2 High light emission luminance.
Further, before step S50, the method further includes:
and A3, dissolving cesium bromide, lead bromide, a large-group organic halide, guanidine thiocyanate and ammonium methyl thiocyanate additives in a dimethyl sulfoxide solvent to obtain the perovskite precursor solution.
In this embodiment, the third preparation process of the perovskite precursor solution is proposed, and the third preparation process of the perovskite precursor solution is as follows: adding cesium bromide (CsBr) and lead bromide (PbBr) 2 ) Dissolving a large-group organic halide, a guanidine thiocyanate (GuSCN) additive and a methyl ammonium thiocyanate (MASCN) additive in a dimethyl sulfoxide (DMSO) solvent, and fully mixing to obtain a perovskite precursor solution.
Further, in the second preparation process of the perovskite precursor solution, the perovskite precursor solution prepared by the preparation method comprises the following components:
CsBr:0.2mol/L;
PbBr 2 :0.2mol/L;
PEACl:0.2mol/L;
GABr:0.1mol/L;
GuSCN:0.007mol/L;
MASCN:0.009mol/L。
referring to the graph of the external quantum efficiency and current density of the blue perovskite light emitting diode prepared by the third preparation process based on the perovskite precursor solution shown in fig. 9, compared with the reference device without the addition of the GuSCN and MASCN additives and without the TOPO passivation treatment, it can be seen that the mixed addition of the GuSCN and MASCN additives in this embodiment raises the external quantum efficiency of the device to 9.25%, and the external quantum efficiency is raised from 9.25% to 11.02% after the TOPO surface passivation treatment.
Referring to the electroluminescence spectra of the correspondingly prepared blue perovskite light emitting diode under different bias voltages in the third preparation process based on the perovskite precursor solution shown in fig. 10, it can be seen that the device subjected to the mixed addition of the GuSCN and MASCN additives and the TOPO passivation shows very good spectral stability, and the spectrum does not shift under the bias voltage change of 3V to 6V.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of other like elements in a process, method, article, or system comprising the element.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) as described above and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, an air conditioner, or a network device) to execute the method according to the embodiments of the present invention.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (8)

1. The blue perovskite light-emitting diode is characterized by sequentially comprising a substrate, an anode, a hole transport layer, a light-emitting layer, a passivation layer, an electron transport layer, an electron injection layer and a cathode from bottom to top, wherein the light-emitting layer is a perovskite thin film prepared from a perovskite precursor solution;
when the blue-light perovskite light-emitting diode is prepared, the perovskite thin film is prepared through a perovskite precursor solution added with a thiocyanate additive, so that the film appearance of the light-emitting layer is adjusted through the thiocyanate additive, wherein the perovskite precursor solution is prepared by dissolving cesium bromide, lead bromide, a large-group organic halide and the thiocyanate additive in a dimethyl sulfoxide solvent, and the perovskite precursor solution comprises the following components: cesium bromide CsBr:0.1-0.3mol/L; lead bromide PbBr2:0.1-0.3mol/L; phenethyl ammonium chloride PEACl:0.1-0.3mol/L; guanidine bromide GABr:0.1-0.3mol/L; thiocyanate salt: 0.05-0.1 mol/L;
after the perovskite thin film is prepared, a passivation layer precursor solution is spin-coated on the perovskite thin film to perform passivation treatment on the perovskite thin film so as to improve the performance of the perovskite thin film, wherein the passivation layer precursor solution is prepared by dissolving a passivation layer material in a chlorobenzene solvent, and the passivation layer material is tri-n-octyl phosphine oxide or triphenylphosphine oxide.
2. The blue-emitting perovskite light-emitting diode of claim 1, wherein the thiocyanate additive comprises a methyl ammonium thiocyanate additive, a guanidine thiocyanate additive, an ammonium thiocyanate additive, or an additive with added guanidine thiocyanate and methyl ammonium thiocyanate.
3. The blue perovskite light emitting diode of claim 1, wherein the thicknesses of the respective layer structures of the blue perovskite light emitting diode are:
the thickness of the anode: 10-300nm;
thickness of the hole transport layer: 20-100nm;
thickness of the passivation layer: 20-100nm;
thickness of the electron transport layer: 20-100nm;
thickness of the electron injection layer: 0.5-3nm;
thickness of the cathode: 50-200nm.
4. The blue perovskite light emitting diode of claim 1, wherein the substrate is a glass substrate;
the anode is indium tin oxide transparent conductive glass or a flexible transparent electrode;
the hole transport layer is one or more of PEDOT, PSS, PVK or Poly-TPD, wherein the PEDOT, the PSS is Poly (3, 4-ethylenedioxythiophene) -polystyrene sulfonic acid, the PVK is polyvinyl carbazole, and the Poly-TPD is Poly [ bis (4-phenyl) (4-butylphenyl) amine ];
the luminescent layer consists of perovskite, large-group organic halide and thiocyanate additive;
the passivation layer is one or more of tri-n-octyl phosphine oxide or triphenylphosphine oxide;
the electron transport layer is TPBi, wherein the TPBi is 1,3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene;
the electron injection layer is lithium fluoride or 8-hydroxyquinoline-lithium;
the cathode is aluminum or silver.
5. A method for preparing a blue perovskite light-emitting diode, which is used for preparing the blue perovskite light-emitting diode as claimed in any one of claims 1 to 4, and comprises the following steps:
providing an ITO glass substrate, and performing pattern design on the ITO glass substrate by using a laser etching process to obtain a first prefabricated object;
sequentially carrying out ultrasonic cleaning on the first prefabricated part by using deionized water, alkali liquor, isopropanol solution and ethanol solution, and drying the cleaned first prefabricated part to obtain a second prefabricated part;
carrying out UV ozone pretreatment on the second prefabricated part to obtain a third prefabricated part;
spin-coating a hole transport layer precursor solution on the third prefabricated object, and performing annealing treatment to obtain a hole transport layer on the ITO glass substrate;
spin-coating the perovskite precursor solution on the hole transport layer, and carrying out annealing treatment to obtain a light-emitting layer;
spin-coating a passivation layer precursor solution on the light-emitting layer to obtain a passivation layer;
and sequentially evaporating an electron transmission layer, an electron injection layer and a cathode on the passivation layer by a vacuum thermal evaporation method to obtain the blue-light perovskite light-emitting diode.
6. The method of manufacturing a blue perovskite light emitting diode according to claim 5, wherein the step of spin coating a hole transport layer precursor solution on the third preform and annealing to obtain a hole transport layer on the ITO glass substrate further comprises:
mixing a PEDOT (4083) solution and a ethanolamine solution to prepare a hole transport layer precursor solution;
wherein the volume ratio of the PEDOT to the PSS (4083) solution to the ethanolamine solution is 1000.
7. The method of manufacturing a blue perovskite light emitting diode according to claim 5, wherein the first preform is subjected to ultrasonic cleaning for a cleaning time period of 10-20min, and the second preform is subjected to UV ozone pretreatment for a treatment time period of 10-20min.
8. The method of manufacturing a blue perovskite light emitting diode as claimed in claim 5, wherein the method of manufacturing a blue perovskite light emitting diode further comprises:
spin-coating the hole transport layer precursor solution on the third prefabricated object at a first preset rotation speed for a first spin-coating time, and annealing at a first preset temperature for a first preset time to obtain a hole transport layer on the ITO glass substrate;
spin-coating the perovskite precursor solution on the hole transport layer at a second preset rotation speed for a second spin-coating time, and annealing at a second preset temperature for a second preset time to obtain a light-emitting layer;
and spin-coating the passivation layer precursor solution on the light-emitting layer at a third preset rotation speed for a third spin-coating time to obtain the passivation layer.
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