CN111293229B - Deep blue light LED based on ternary copper-based iodide nanocrystalline and preparation method thereof - Google Patents
Deep blue light LED based on ternary copper-based iodide nanocrystalline and preparation method thereof Download PDFInfo
- Publication number
- CN111293229B CN111293229B CN202010147959.3A CN202010147959A CN111293229B CN 111293229 B CN111293229 B CN 111293229B CN 202010147959 A CN202010147959 A CN 202010147959A CN 111293229 B CN111293229 B CN 111293229B
- Authority
- CN
- China
- Prior art keywords
- transport layer
- deep blue
- nanocrystalline
- layer
- hole transport
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
- H10K50/115—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising active inorganic nanostructures, e.g. luminescent quantum dots
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Nanotechnology (AREA)
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Manufacturing & Machinery (AREA)
- Electroluminescent Light Sources (AREA)
Abstract
The invention belongs to the technical field of semiconductor light-emitting devices, and particularly relates to a deep blue light LED based on ternary copper-based iodide nanocrystals and a preparation method thereof. The LED comprises a transparent conductive substrate, a hole transport layer, and Cs 3 Cu 2 I 5 A nanocrystalline luminescent layer, an electron transport layer and a contact electrode. The invention adopts the high-temperature heat injection method to prepare the Cs 3 Cu 2 I 5 The nanocrystalline is used as a luminous layer, so that the toxicity problem of the traditional lead halide is avoided; and the typical zero-dimensional structural characteristics of the material enable the material to have excellent stability, so that the defect of the working stability of the LED prepared from the traditional lead halide is overcome, and the working life of the prepared device under the driving voltage of 7V is up to 108 hours. The structural design of the device provides a feasible scheme for the preparation research of the stable and environment-friendly deep blue light LED.
Description
Technical Field
The invention belongs to the technical field of semiconductor light-emitting devices, and particularly relates to a deep blue light LED and a preparation method thereof.
Background
Deep blue LEDs with high energy efficiency are widely used in the fields of wide color gamut display, white light illumination, and fluorescence-based chemical and biological sensors, as one of the mainstream solid-state light sources. However, the current blue LED is mainly prepared based on III-V InGaN semiconductor materials, the preparation technique relies on expensive high-temperature and high-pressure growth equipment, such as molecular beam epitaxy and metal organic chemical vapor deposition, and the growth process of each functional layer is complicated. Therefore, from the viewpoint of application, development of a blue light emitting material which is inexpensive, excellent in performance and environmentally friendly is urgently required.
In recent years, the potential application of metal halide perovskite materials in the field of luminescence has attracted people's attention, and the advantages of low cost, high fluorescence quantum yield, high luminescent purity and wide spectrum adjustable range make the metal halide perovskite materials have great development prospects in the field of luminescence. Currently, the external quantum efficiency of red and green LEDs based on traditional lead halide perovskites has exceeded 20% (k.b.lin, j.xing, l.n.quan, f.p.d.arquer, x.w.gong, j.x.lu, l.q.xie, w.j.zhao, d.zhang, c.z.yan, w.q.li, x.liu, y.lu, j.kiran, e.h.sargent, q.h.xiong, and z.h.wei, nature 562,245 (2018); y.shen, l.p.chen, y.q.li, w.li, j.d.chen, s.t.lee, and j.x.tang, adv.mater.31, 1517 (2019)), can be comparable to traditional organic and cadmium based perovskites, but the LED devices have a slow operating point to yield and a high quantum efficiency. The reason is mainly as follows: the blue perovskite LED needs to be prepared by adopting a halogen mixing strategy, but due to the migration problem of halogen anions under an electric field, the component spatial distribution of a luminescent layer is not uniform any more, and the color of the prepared device can be changed after being electrified, so that the spectrum is unstable. More importantly, the currently reported blue perovskite LEDs are all traditional lead halide perovskites, with inherent deficiencies in lead toxicity, harmful to humans and the environment (j.sun, j.yang, j.i.lee, j.h.cho, and m.s.kang, j.phys.chem.lett.9,1573 (2018)). Therefore, the search for a lead-free material with blue light emission characteristics, low preparation cost, stability and environmental friendliness as a light emitting layer of an LED undoubtedly has important scientific significance and research value.
Considering ternary copper-based iodide Cs 3 Cu 2 I 5 The material is environment-friendly, non-toxic and deep blue intrinsic light emitting, and the material has excellent stability due to the typical zero-dimensional structural characteristics. If Cs can be used 3 Cu 2 I 5 The material is used as a luminescent layer to research and prepare the efficient and stable deep blue light LED which is novel, cheap and high in efficiencyThe development of efficient blue light solid-state light sources provides a new strategy.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a deep blue LED based on ternary copper-based iodide nanocrystalline and a preparation method thereof, wherein nontoxic and stable Cs is adopted 3 Cu 2 I 5 The nanocrystalline is used as a luminous layer to realize the deep blue light emission of the device under the electric drive, so that the deep blue light LED with long service life and environmental friendliness is obtained.
In order to achieve the purpose, the invention provides the following technical scheme: a deep blue light LED based on ternary copper-based iodide nanocrystalline comprises a transparent conductive substrate, wherein a hole transport layer and Cs are sequentially arranged on the transparent conductive substrate 3 Cu 2 I 5 A nanocrystalline light emitting layer, an electron transport layer and a contact electrode.
The transparent conductive substrate is an ITO conductive glass substrate or a flexible substrate plated with an ITO thin layer, the thickness of the ITO thin layer is 100-120 nanometers, and the resistivity is 5.0 multiplied by 10 -4 ～1.0×10 -3 Ohm cm.
The hole transport layer is a p-type NiO film with a thickness of 50-100 nm and a resistivity of 5.0 × 10 -2 ～1.0×10 -1 Ohm cm.
Cs 3 Cu 2 I 5 The thickness of the nanocrystalline luminescent layer is 120-200 nanometers, wherein the size of a single nanocrystalline is 15-20 nanometers.
The electron transport layer is 1,3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene, and the thickness of the electron transport layer is 30-50 nanometers.
The contact electrode is made of a composite material of LiF and metal Al, and the thickness of the contact electrode is 40-60 nanometers.
The preparation method of the deep blue light LED based on the ternary copper-based iodide nanocrystal comprises the following steps: (1) cleaning the transparent conductive substrate;
(2) Preparing a hole transport layer on the transparent conductive substrate by adopting a magnetron sputtering method or a metal organic chemical vapor deposition method;
(3) Preparation of deep blue light emitting Cs by high temperature thermal injection method 3 Cu 2 I 5 Preparing Cs on the hole transport layer by adopting a solution spin coating mode through a nanocrystalline solution 3 Cu 2 I 5 A nanocrystalline light-emitting layer;
(4) By thermal evaporation on Cs 3 Cu 2 I 5 Depositing an electron transport layer on the nanocrystalline light emitting layer;
(5) And depositing an electrode on the electron transport layer by a thermal evaporation method.
Preferably, the high temperature and high temperature injection method in the step (3) is realized according to the following mode: mixing 0.22 mmol of cesium carbonate, 0.5 mmol of oleic acid and 5 mmol of octadecene, heating to 100 ℃, keeping under nitrogen for 2 hours, raising the temperature to 160 ℃, injecting 1 ml of cuprous iodide precursor at 160 ℃, and rapidly cooling by using an ice-water bath after reacting for 10 seconds; cooling, taking out the original solution, centrifuging to obtain precipitate, and dispersing the precipitate in n-hexane to obtain Cs 3 Cu 2 I 5 And (4) a nanocrystalline solution.
Preferably, the solution spin coating in step (3) is implemented as follows: under the protection of inert gas, adding Cs 3 Cu 2 I 5 Uniformly spin-coating the nanocrystal solution on the hole transport layer under the conditions of low speed of 500 rpm/5 s and high speed of 3000 rpm/30 s; finally, annealing the spin-coated sample at 50 ℃ for 10 minutes to obtain the deep blue light-emitting Cs 3 Cu 2 I 5 A nanocrystalline light emitting layer.
The invention adopts nontoxic and stable Cs 3 Cu 2 I 5 The nanocrystalline is used as a luminous layer, so that the preparation of a novel deep blue light LED which is efficient, stable and environment-friendly is realized. On one hand, the device shields the use of heavy metal from materials, and avoids the harm to human bodies and the environment; on the other hand, cs 3 Cu 2 I 5 The typical zero-dimensional structural characteristics of the material enable the material to have excellent stability, so that the device can stably work under direct current bias, and the working life of the device under the driving voltage of 7 volts reaches 108 hours. Therefore, the LED in the invention can overcome the defects of the traditional lead halide perovskite LEDLead toxicity and working stability, thereby providing a feasible scheme for the preparation and research of the stable and environment-friendly deep blue light LED.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a deep blue LED based on ternary copper-based iodide nanocrystals according to the present invention;
FIG. 2 is a scanning electron micrograph of a NiO thin film for a hole transport layer in example 1;
FIG. 3 shows Cs for light-emitting layer in example 1 3 Cu 2 I 5 Transmission electron microscope photograph of the nanocrystal;
FIG. 4 is a scanning electron micrograph of a NiO film for a hole transport layer in example 2;
fig. 5 is an external quantum efficiency-voltage characteristic curve of the deep blue LED prepared in example 1;
FIG. 6 is an electroluminescence spectrum of a deep blue LED prepared in example 1 at various voltages;
FIG. 7 is a graph showing the variation of light emission intensity of the deep blue LED prepared in example 1 continuously operated at 7.0V;
fig. 8 is an external quantum efficiency-voltage characteristic curve of the deep blue LED prepared in example 2;
fig. 9 is an external quantum efficiency-voltage characteristic curve of the deep blue LED prepared in example 3.
Wherein: 1. transparent conductive substrate, 2. Hole transport layer, 3.Cs 3 Cu 2 I 5 A nanocrystalline light emitting layer, 4, an electron transport layer, 5, a contact electrode.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in figure 1, the deep blue light LED based on the ternary copper-based iodide nanocrystalline comprises a transparent conductive substrate 1, wherein a hole transport layer 2 and Cs are sequentially arranged on the transparent conductive substrate 1 3 Cu 2 I 5 A nanocrystalline light-emitting layer 3, an electron transport layer 4, and a contact electrode 5.
Wherein, the transparent conductive substrate 1 is an ITO conductive glass substrate or a flexible substrate plated with an ITO thin layer, the thickness of the ITO thin layer is 100-120 nanometers, and the resistivity is 5.0 multiplied by 10 -4 ～1.0×10 -3 Ohm cm.
Preferably, the hole transport layer 2 is a p-type NiO thin film having a thickness of 50 to 100 nm and a resistivity of 5.0X 10 -2 ～1.0×10 -1 Ohm cm. Generally, a larger hole transport layer thickness will cause reabsorption of emitted photons in the active region, while a smaller hole transport layer thickness is detrimental to the hole injection process into the active region, thereby affecting the luminous efficiency of the LED.
The NiO hole transport layer is prepared by adopting a magnetron sputtering method, the sputtering power is 120 watts, the sputtering pressure is 0.8 pascal, the sputtering temperature is 250 ℃, the working gas is a mixed gas of argon and oxygen, and the volume ratio of the argon to the oxygen is 3.
In addition, the preparation of the NiO hole transport layer can also be completed by adopting a metal organic chemical vapor deposition method, which specifically comprises a two-step growth method: the first step of growth is low-temperature growth, the growth temperature is 400 ℃, and the growth time is 3 minutes; the second growth step is high temperature growth at 590 deg.c for 20 min.
Cs 3 Cu 2 I 5 The thickness of the nanocrystal light emitting layer 3 is 120 to 200 nm, wherein the size of a single nanocrystal is 15 to 20 nm.
The electron transport layer 4 is 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi) with a thickness of 30 to 50 nm. TPBi is prepared by thermal evaporation method with evaporation pressure of 2.0 × 10 -4 Pascal.
The contact electrode 5 is made of a composite material of LiF and metal Al, is prepared by a thermal evaporation method, has a thickness of 40-60 nanometers and an evaporation pressure of 2.0 multiplied by 10 -4 Pascal.
The preparation method of the deep blue light LED based on the ternary copper-based iodide nanocrystal comprises the following steps: (1) cleaning a transparent conductive substrate 1;
(2) Preparing a hole transport layer 2 on a transparent conductive substrate 1 by adopting a magnetron sputtering method or a metal organic chemical vapor deposition method;
(3) Preparation of deep blue light emitting Cs by high temperature thermal injection method 3 Cu 2 I 5 Preparing Cs on the hole transport layer 2 by adopting a nano-crystalline solution and adopting a solution spin coating mode 3 Cu 2 I 5 A nanocrystalline light-emitting layer 3;
(4) By thermal evaporation on Cs 3 Cu 2 I 5 An electron transport layer 4 is deposited on the nanocrystalline light-emitting layer 3;
(5) The contact electrode 5 is deposited on the electron transport layer 4 using thermal evaporation.
Preferably, the high temperature and high temperature injection method in the step (3) is realized according to the following mode: 0.22 mmole of cesium carbonate (Cs) 2 CO 3 ) 0.5 mmol Oleic Acid (OA) and 5 mmol Octadecene (ODE) were mixed and heated to 100 ℃ and kept under nitrogen for 2 hours, after which the temperature was raised to 160 ℃ and 1 ml prepared cuprous iodide precursor was injected at 160 ℃ and after reaction for 10 seconds it was rapidly cooled using an ice water bath; cooling, taking out the original solution, centrifuging to obtain precipitate, and dispersing the precipitate in n-hexane to obtain Cs 3 Cu 2 I 5 And (4) a nanocrystal solution.
Further, the solution spin coating in the step (3) is realized according to the following mode: under the protection of inert gas, adding Cs 3 Cu 2 I 5 Uniform spin coating of nanocrystalline solutionSpin coating conditions on the hole transport layer 2 were 500 rpm/5 sec at low speed and 3000 rpm/30 sec at high speed; finally, annealing the spin-coated sample at 50 ℃ for 10 minutes to obtain the deep blue light emitting Cs 3 Cu 2 I 5 A nanocrystalline light-emitting layer 3.
Example 1:
(1) And cleaning the transparent conductive substrate 1, wherein the adopted substrate is ITO conductive glass.
ITO conductive glass is used as a substrate, the thickness of an ITO thin layer is 110 nanometers, and the resistivity is 1.0 multiplied by 10 -3 Ohm cm, and carrying out chemical cleaning on the glass substrate, wherein the cleaning steps are as follows: firstly, putting a substrate into a cleaning agent (Libai brand liquid detergent) to be soaked for 20 minutes, and then washing the substrate clean by tap water; then putting the mixture into distilled water for ultrasonic cleaning for 10 minutes; then ultrasonic cleaning is carried out for 5 minutes by acetone and ethanol solution respectively in sequence, and the operation is circulated once again; then washing the mixture by deionized water, and drying the mixture by high-purity nitrogen for later use.
(2) And placing the cleaned transparent conductive substrate 1 in a magnetron sputtering cavity, and completing sputtering of the hole transport layer 2 by adopting a radio frequency power supply.
Mounting a high-purity NiO ceramic target, and adjusting the distance between the target and the substrate to 15 cm; starting the mechanical pump to vacuumize the sputtering cavity, starting the molecular pump to continue vacuumizing when the vacuum degree of the cavity is lower than 5 pascals until the vacuum degree of the cavity is lower than 1.0 multiplied by 10 -4 Pascal; introducing high-purity argon and oxygen into the sputtering cavity, and adjusting the volume ratio of the high-purity argon to the oxygen to 3; starting a radio frequency source, setting the power of the radio frequency source to 120 watts, and setting the temperature of a substrate to 250 ℃; the sputtering time was 30 minutes, and the thickness of the resulting NiO hole transport layer was 80 nm, and the resistivity thereof was 6.0X 10 -2 Ohm cm.
Fig. 2 is a scanning electron micrograph of the hole transport layer 2 prepared by the magnetron sputtering method, and it can be seen from the figure that the size of NiO nano-crystal grains is about 70 nm, and adjacent crystal grains are closely connected. However, the surface coverage of the entire film was not high, and many voids appeared.
(3) Preparation of deep blue light emitting Cs by high temperature thermal injection method 3 Cu 2 I 5 Preparing Cs by using nanocrystalline solution and adopting solution spin-coating method 3 Cu 2 I 5 A nanocrystalline light emitting layer 3.
0.22 mmole of Cs 2 CO 3 (Aladdin brand), 0.5 mmole OA (Aladdin brand) and 5 mmole ODE (Aladdin brand) were mixed and heated to 100 ℃ for 2 hours under nitrogen to remove residual water from the drug. Thereafter, the temperature was raised to 160 ℃ and 1 ml of the prepared CuI (Aladdin brand) precursor was injected at 160 ℃ and rapidly cooled using an ice water bath after 10 seconds of reaction. Thereafter, the original solution was taken out and centrifuged at 10000 rpm to obtain a precipitate, and the precipitate was dispersed in n-hexane; under the protection of inert gas, cs is dispersed 3 Cu 2 I 5 The n-hexane solution of the nanocrystals is uniformly spin-coated on the hole transport layer 2 under the following conditions: 500 rpm/5 s at low speed and 3000 rpm/30 s at high speed; finally, annealing the spin-coated sample at about 50 ℃ for 10 minutes to finally obtain the deep blue light-emitting Cs 3 Cu 2 I 5 A nanocrystalline light emitting layer 3. Prepared Cs 3 Cu 2 I 5 The thickness of the nanocrystalline light emitting layer was 130 nm.
FIG. 3 shows Cs prepared by high temperature thermal injection 3 Cu 2 I 5 Transmission electron micrograph of nanocrystal from which Cs can be seen 3 Cu 2 I 5 The nanocrystals are ellipsoidal and have an obvious self-assembly characteristic, with the average size of about 17 nm.
(4) Spin-coating the Cs 3 Cu 2 I 5 And a sample of the nanocrystalline light-emitting layer 3 is placed in a vacuum evaporation chamber, and the preparation of the electron transmission layer 4 is completed by adopting a thermal evaporation method.
The method comprises the following specific steps: firstly, 2 g of TPBi (Aladdin brand) powder is placed in a crucible; then will carry Cs 3 Cu 2 I 5 The sample of the nanocrystalline light emitting layer was placed upside down at a distance of 30 cm above the crucible; starting a mechanical pump to vacuumize the evaporation chamberAfter the vacuum degree of the cavity is lower than 5 pascals, starting the molecular pump to continuously pump the vacuum until the vacuum degree of the cavity is lower than 2.0 multiplied by 10 -4 Starting evaporation in pascal; the evaporation power is set to be 30 watts, the evaporation rate is 5 angstroms per second, the evaporation time is 80 seconds, and the thickness of the TPBi electron transport layer obtained finally is 40 nanometers.
(5) Depositing a LiF (Aladdin) and Al composite electrode on the surface of the electron transport layer 4 by adopting a thermal evaporation method and combining a mask plate, wherein the evaporation pressure is 2.0 multiplied by 10 -4 Pascal, the obtained LiF thickness is 1 nanometer, and the thickness of the metallic Al layer is 50 nanometers. Evaporating LiF first and then evaporating Al.
Example 2:
the difference between this embodiment and embodiment 1 is that the preparation of the hole transport layer 2 is completed by metal organic chemical vapor deposition, and the specific steps are as follows: ITO conductive glass is used as a substrate, the cleaned substrate is placed on a graphite tray of a metal organic chemical vapor deposition reaction chamber, and a NiO film is grown by a two-step growth method to serve as a hole transport layer 2 of the LED. The specific growth conditions were as follows: solid metal organic source methyl nickel cyclopentadienyl is adopted as a nickel source, and high-purity oxygen is adopted as an oxygen source; in the first step, the input amount of a nickel source is set to be 0.09 micromole per minute, the input amount of an oxygen source is set to be 0.12 micromole per minute, the growth temperature is set to be 450 ℃, the reaction pressure is 76 pascal, and the growth time is 3 minutes; in the second step, the input of the nickel source was set to 0.12 micromole per minute, the input of the oxygen source was set to 0.12 micromole per minute, the growth temperature was set to 590 ℃, the reaction pressure was 120 pascal, and the growth time was 20 minutes. The thickness of the prepared p-type NiO film is 90 nanometers, and the resistivity of the p-type NiO film is 1.0 multiplied by 10 -1 Ohm cm.
Fig. 4 is a scanning electron microscope photograph of a NiO hole transport layer prepared by using a metal organic chemical vapor deposition method, from which the cubic structural features of NiO grains can be clearly observed, adjacent NiO nano grains are closely arranged, and no obvious void is formed in a film layer. The steps of the other film layers in this example are the same as those in example 1.
In the embodiment, the preparation of the NiO hole transport layer is completed by adopting a metal organic chemical vapor deposition method, so that the crystallization quality of the NiO film can be optimized through a two-step growth process, the surface coverage rate of the film is higher, and the reduction of the leakage current of a device is facilitated.
Example 3:
the difference between this embodiment and embodiment 1 is that the selected transparent conductive substrate is a flexible PET substrate plated with an ITO thin layer, the thickness of the ITO thin layer is 120 nm, and the resistivity is 8.0 × 10 -4 Ohm cm. The cleaning steps are as follows: firstly, putting a substrate into a cleaning agent (Libai brand liquid detergent) to be soaked for 10 minutes, and then washing the substrate with tap water; then ultrasonic cleaning is carried out for 5 minutes by acetone and ethanol solution respectively in turn; then washing the mixture by deionized water, and drying the mixture by high-purity nitrogen for later use.
In addition, the NiO hole transport layer is prepared by adopting a magnetron sputtering method. Unlike example 1, the substrate temperature was set to 120 ℃ during sputtering, which prevented damage to the flexible PET material due to excessive temperatures, and other sputtering conditions were not changed. The thickness of the NiO hole transport layer obtained finally is 60 nanometers, and the resistivity is 5.5 multiplied by 10 -2 Ohm cm.
The process steps for preparing the other layers of the film are the same as those in example 1.
In the embodiment, the flexible PET plated with the ITO thin layer is used as the substrate, so that the prepared deep blue LED can be bent and folded, and possible preparation schemes are provided for emerging wearable electronic devices, flexible display applications and the like.
Fig. 5 is an external quantum efficiency curve of the deep blue LED prepared in example 1 at different driving voltages, when the Al electrode of the device is connected to the negative electrode of the dc power supply and the ITO layer is connected to the positive electrode of the power supply. It can be seen from the figure that the external quantum efficiency of the device increases gradually with increasing voltage, reaching a maximum of 1.12% at 7.5 volts. Subsequently, the external quantum efficiency of the device begins to slowly decline, possibly due to thermal effects at high driving voltages.
Fig. 6 is an electroluminescence spectrum of the deep blue LED prepared in example 1 at various voltages, from which it can be seen that the device exhibits deep blue light emission with a light emission peak at 466 nm. In the range of 4.0-8.0V, the luminous intensity of the device is gradually enhanced, and the peak position and the peak shape are not changed.
Fig. 7 is a variation curve of the light emitting intensity of the deep blue LED prepared in example 1 continuously operated at 7.0 v, and the light emitting intensity of the device was monitored in real time while the operating voltage of the device was kept constant during the experiment. As can be seen from the figure, the device exhibited excellent operational stability with a slow decay in luminous intensity over time of 50% over 108 hours, far superior to conventional lead halide perovskite LEDs.
Fig. 8 is an external quantum efficiency-voltage characteristic curve of the deep blue LED prepared in example 2, which has the same trend as in example 1, and the external quantum efficiency reaches a maximum (0.64%) at a device operating voltage of 7.5 v. The external quantum efficiency of the deep blue LED prepared in example 2 was lower compared to example 1, which is mainly due to the higher resistivity of the NiO thin film prepared by the mocvd and the low hole injection efficiency.
Fig. 9 is an external quantum efficiency-voltage characteristic curve of the deep blue LED prepared in example 3, which has a similar trend to examples 1 and 2, and the external quantum efficiency of the device reaches a maximum of 0.58% at 7.0 v. Compared with the embodiment 1, the external quantum efficiency of the deep blue LED prepared in the embodiment 3 is lower, which is mainly caused by that when a device is prepared by adopting a flexible substrate, the sputtering temperature of the hole transport layer (2) is lower, the material growth rate is slower, and the thickness of the obtained NiO film is smaller; in addition, the lower substrate temperature also causes the crystallization quality of the hole transport layer (2) to be reduced, the probability that hole carriers are trapped by defects in the injection process is increased, and finally the radiation recombination efficiency of electrons and holes in the active region is lower.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (4)
1. A deep blue LED based on ternary copper-based iodide nanocrystals, comprising a transparent conductive substrate (1), characterized in that: a hole transport layer (2) and Cs are sequentially arranged on the transparent conductive substrate (1) 3 Cu 2 I 5 A nanocrystalline light-emitting layer (3), an electron transport layer (4), and a contact electrode (5);
the hole transport layer (2) is a p-type NiO film with the thickness of 50-100 nanometers and the resistivity of 5.0 multiplied by 10 -2 ～1.0×10 -1 Ohm cm;
Cs 3 Cu 2 I 5 the thickness of the nanocrystal light-emitting layer (3) is 120-200 nanometers, wherein the size of a single nanocrystal is 15-20 nanometers;
the electron transport layer (4) is 1,3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene, and the thickness of the electron transport layer is 30-50 nanometers;
preparation of deep blue light emitting Cs by high temperature thermal injection method 3 Cu 2 I 5 Preparing Cs on the hole transport layer by adopting a solution spin coating mode through a nanocrystalline solution 3 Cu 2 I 5 A nanocrystalline light-emitting layer;
the high-temperature thermal injection method is realized according to the following modes: mixing and heating 0.22 mmol of cesium carbonate, 0.5 mmol of oleic acid and 5 mmol of octadecene to 100 ℃ and keeping under nitrogen for 2 hours, then heating to 160 ℃, injecting 1 ml of cuprous iodide precursor liquid at 160 ℃, and after reacting for 10 seconds, rapidly cooling by using an ice-water bath; cooling, taking out the original solution, centrifuging to obtain precipitate, and dispersing the precipitate in n-hexane to obtain Cs 3 Cu 2 I 5 The nano-crystalline solution is prepared by dissolving the nano-crystalline,
the spin coating of the solution is realized according to the following modes: under the protection of inert gas, adding Cs 3 Cu 2 I 5 The nanocrystalline solution is uniformly spin-coated on the hole transport layer under the conditions of low speed of 500 rpm/5 s and high speedSpeed 3000 rpm/30 seconds; finally, annealing the spin-coated sample at 50 ℃ for 10 minutes to obtain the deep blue light-emitting Cs 3 Cu 2 I 5 A nanocrystalline light emitting layer.
2. The deep blue LED based on ternary copper-based iodide nanocrystals according to claim 1, wherein: the transparent conductive substrate (1) is an ITO conductive glass substrate or a flexible substrate plated with an ITO thin layer, the thickness of the ITO thin layer is 100-120 nanometers, and the resistivity is 5.0 multiplied by 10 -4 ～1.0×10 -3 Ohm cm.
3. The deep blue LED based on ternary copper-based iodide nanocrystals according to claim 1, wherein: the contact electrode (5) is a composite material of LiF and metal Al, and the thickness of the contact electrode is 40-60 nanometers.
4. A method for preparing a deep blue LED based on ternary copper-based iodide nanocrystals according to any of claims 1 to 3, characterized in that it is carried out according to the following steps:
(1) Cleaning a transparent conductive substrate (1);
(2) Preparing a hole transport layer (2) on the transparent conductive substrate (1) by adopting a magnetron sputtering method or a metal organic chemical vapor deposition method;
(3) Preparation of deep blue light emitting Cs by high temperature thermal injection method 3 Cu 2 I 5 Preparing Cs on the hole transport layer (2) by adopting a nano-crystalline solution and adopting a solution spin coating mode 3 Cu 2 I 5 A nanocrystalline light-emitting layer (3);
(4) By thermal evaporation on Cs 3 Cu 2 I 5 An electron transmission layer (4) is deposited on the nanocrystalline light-emitting layer (3);
(5) And depositing an electrode (5) on the electron transport layer (4) by adopting a thermal evaporation method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010147959.3A CN111293229B (en) | 2020-03-05 | 2020-03-05 | Deep blue light LED based on ternary copper-based iodide nanocrystalline and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010147959.3A CN111293229B (en) | 2020-03-05 | 2020-03-05 | Deep blue light LED based on ternary copper-based iodide nanocrystalline and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111293229A CN111293229A (en) | 2020-06-16 |
| CN111293229B true CN111293229B (en) | 2023-02-03 |
Family
ID=71020959
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010147959.3A Active CN111293229B (en) | 2020-03-05 | 2020-03-05 | Deep blue light LED based on ternary copper-based iodide nanocrystalline and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111293229B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111661867B (en) * | 2020-06-30 | 2022-04-29 | 重庆大学 | Preparation method of lead-free cesium copper chloride nanocrystalline and product and application thereof |
| CN115108575B (en) * | 2021-03-22 | 2023-08-18 | 郑州大学 | Zero-dimensional Cs 2 CuCl 4 Nanocrystalline, green light LED and preparation method thereof |
| CN113113520B (en) * | 2021-04-06 | 2022-12-20 | 中山大学 | All-solid-state light source based on cesium copper iodide (CsCuI) semiconductor and preparation method thereof |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110459640A (en) * | 2019-07-15 | 2019-11-15 | 郑州大学 | One kind being based on Cs3Cu2I5Self energizing photodetector of perovskite and preparation method thereof |
-
2020
- 2020-03-05 CN CN202010147959.3A patent/CN111293229B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110459640A (en) * | 2019-07-15 | 2019-11-15 | 郑州大学 | One kind being based on Cs3Cu2I5Self energizing photodetector of perovskite and preparation method thereof |
Non-Patent Citations (4)
| Title |
|---|
| Cesium Copper Iodide Tailored Nanoplates and Nanorods for Blue，Yellow, and White Emission;Parth Vashishtha et al;《CHEMISTRY OF MATERIALS》;20191014;第9003-9011页 * |
| Lead-Free Highly Efficient Blue-Emitting Cs 3 Cu 2 I 5 with 0D Electronic Structure;Taehwan Jun et al;《ADVANCED MATERIALS》;20181214;第1084547（1-6）页 * |
| Taehwan Jun et al.Lead-Free Highly Efficient Blue-Emitting Cs 3 Cu 2 I 5 with 0D Electronic Structure.《ADVANCED MATERIALS》.2018, * |
| Transparent amorphous oxide semiconductors for organic electronics: Application to inverted OLEDs;Hideo Hosono et al;《PNAS》;20170110;全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111293229A (en) | 2020-06-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Rahman | Zinc oxide light-emitting diodes: a review | |
| CN111293229B (en) | Deep blue light LED based on ternary copper-based iodide nanocrystalline and preparation method thereof | |
| CN110387227B (en) | Perovskite thin film, perovskite electroluminescent device, preparation method and display device | |
| WO2021103471A1 (en) | Self-assembling multi-dimensional quantum well cspbx3 perovskite nanocrystalline light-emitting diode | |
| Zhuang et al. | Air-stable all inorganic green perovskite light emitting diodes based on ZnO/CsPbBr3/NiO heterojunction structure | |
| CN108075020B (en) | Light-emitting diode based on cesium-lead halogen perovskite thin film material and preparation method thereof | |
| CN111341942B (en) | Electric injection yellow light-emitting diode (LED) based on lead-free copper-based iodide and preparation method thereof | |
| CN108281572B (en) | Perovskite light emitting diode of the compound containing inferior ethoxyl and preparation method thereof | |
| CN112186117B (en) | Alternating current driving type quantum dot light-emitting diode and preparation method thereof | |
| CN105789398B (en) | Perovskite LED and preparation method using ZnO nano fence net network as electron injecting layer | |
| KR20070036835A (en) | Method for preparation of organic light emitting devices comprising inorganic buffer layer | |
| Guo et al. | Interface engineering improves the performance of green perovskite light-emitting diodes | |
| CN113285049B (en) | Method for preparing tungsten trioxide OLED external light extraction layer with high light extraction efficiency by ultrasonic spraying | |
| CN110739411A (en) | preparation method of perovskite light-emitting diode capable of improving performance | |
| CN110416420B (en) | Quantum dot light-emitting diode and preparation method thereof | |
| CN112259701A (en) | Perovskite thin film and preparation method and application thereof | |
| CN104124317A (en) | Neodymium-dope inorganic electroluminescent infrared light-emitting device and manufacturing method thereof | |
| CN113921732B (en) | CsPbI3 efficient LED based on 4-iodine-D-phenylalanine post-treatment and preparation method thereof | |
| CN109904334A (en) | Multilayer hybrid inorganic-organic perovskite light emitting diode and preparation method thereof | |
| CN114665051A (en) | Preparation method of perovskite light-emitting diode with regulated light-emitting layer | |
| CN113903867A (en) | Electroluminescent LED and preparation method thereof | |
| Zhang et al. | Perovskite light-emitting diodes for uniform eight-segment displays | |
| CN115108575B (en) | Zero-dimensional Cs 2 CuCl 4 Nanocrystalline, green light LED and preparation method thereof | |
| CN112625681A (en) | Blue InP/ZnS quantum dot, preparation method thereof and application thereof in QLED | |
| CN114891498B (en) | Nanocrystalline film of cation coated one-dimensional perovskite and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |