CN116656337A - Nanoparticle, nanoparticle composition, light emitting diode, and display device - Google Patents

Nanoparticle, nanoparticle composition, light emitting diode, and display device Download PDF

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CN116656337A
CN116656337A CN202210153051.2A CN202210153051A CN116656337A CN 116656337 A CN116656337 A CN 116656337A CN 202210153051 A CN202210153051 A CN 202210153051A CN 116656337 A CN116656337 A CN 116656337A
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shell layer
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周礼宽
杨一行
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TCL Technology Group Co Ltd
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Priority to PCT/CN2022/142616 priority patent/WO2023155605A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/04—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction
    • H01L33/06—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier

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Abstract

The application discloses a nanoparticle, which comprises a core/a 1 st shell layer/a … …/an n-th shell layer, wherein the lattice mismatch degree between adjacent shell layers is less than or equal to 5%. The lattice mismatch degree between adjacent shell layers in the nano particles is less than or equal to 5%, so that interface defects can be reduced, the stability and fluorescence quantum efficiency of the nano particles are improved, and the luminous efficiency and the service life of the light-emitting diode prepared by using the nano particles are further improved. In addition, the application also discloses a nanoparticle composition comprising the nanoparticle, a light-emitting diode and a display device.

Description

Nanoparticle, nanoparticle composition, light emitting diode, and display device
Technical Field
The present application relates to the field of display technologies, and in particular, to a nanoparticle, a nanoparticle composition including the nanoparticle, a light emitting diode, and a display device.
Background
Quantum dot materials are widely used in the field of luminescence, such as luminescent layer materials for quantum dot light emitting diodes (QLEDs), due to their unique optical properties. Compared with an Organic Light Emitting Diode (OLED), the quantum dot light emitting diode has the advantages of narrow light emitting spectrum, wide color gamut, good stability, low manufacturing cost and the like.
In the qd-led, there is a problem that the electron and hole injection of the light emitting layer is unbalanced, for example, the electron injection is more than the hole injection (i.e., the electron is excessive), and the unbalance of the electron and the hole can cause the qd to be in a charged state, and the charged qd can generate non-radiative auger recombination, which finally results in a short lifetime of the qd-led.
In addition, the fluorescence efficiency of the existing quantum dots is not high enough, so that the efficiency of the light emitting diode is low.
Disclosure of Invention
In view of the above, the present application provides a nanoparticle, which aims to solve the problem of low fluorescence efficiency of the existing nanoparticle.
The embodiment of the application is realized in such a way that the structure of the nanoparticle comprises a core/1 st shell/nth shell, and the lattice mismatch degree between adjacent shells is less than or equal to 5%.
Alternatively, in some embodiments of the application, the lattice mismatch between the core and the 1 st shell layer is 5% or less.
Optionally, in some embodiments of the present application, n is an integer greater than or equal to 2, and the material of the 2 nd shell layer of the nanoparticle is CdZnS.
Alternatively, in some embodiments of the present application, the molar amount of Cd in the 2 nd shell CdZnS is 10 to 50% of the total molar amount of Cd and Zn.
Alternatively, in some embodiments of the present application, the nanoparticle has a light emission wavelength of 647-760 nm, and the molar amount of Cd in the 2 nd shell CdZnS is 25-50% of the total molar amount of Cd and Zn; or alternatively
The luminescence wavelength of the nano particles is 492-550 nm, and the molar quantity of Cd in the 2 nd shell layer CdZnS is 15-25% of the total molar quantity of Cd and Zn; or alternatively
The luminescence wavelength of the nano particles is 430-455 nm, and the molar quantity of Cd in the 2 nd shell CdZnS is 10-25% of the total molar quantity of Cd and Zn.
Alternatively, in some embodiments of the application, the band gap of the core ranges from 1.9 to 2.75eV; and/or
The forbidden band width Eg of the core and each shell layer satisfies the following conditions: eg Nuclear ＜Eg 1 st shell layer ＜······＜Eg Nth shell layer 。
Alternatively, in some embodiments of the present application, the core and the shell other than the 2 nd shell each independently include at least one of Zn, cd, and each independently include at least one of Te, se, and S.
Optionally, in some embodiments of the present application, the x-th shell layer and the x+1-th shell layer of the nanoparticle include both Cd and Zn, wherein 1.ltoreq.x < n, the ratio of the molar amount of Cd in the x+1-th shell layer to the total molar amount of Cd and Zn is smaller than the ratio of the molar amount of Cd in the x-th shell layer to the total molar amount of Cd and Zn, and the forbidden band width Eg of the core and each shell layer satisfies Eg Nuclear ＜Eg 1 st shell layer ＜······＜Eg Nth shell layer 。
Alternatively, in some embodiments of the present application, the n is greater than 2, the 3 rd shell of the nanoparticle comprises Cd and Zn, the ratio of the molar amount of Cd in the 3 rd shell to the total molar amount of Cd and Zn is smaller than the ratio of the molar amount of Cd in the 2 nd shell to the total molar amount of Cd and Zn, and the forbidden bandwidths of the 2 nd shell and the 3 rd shell satisfy Eg 2 nd shell layer ＜Eg 3 rd shell layer The method comprises the steps of carrying out a first treatment on the surface of the Or alternatively
The n is more than 2, the material of the 3 rd shell layer of the nano particle is ZnS, and the forbidden bandwidths of the 2 nd shell layer and the 3 rd shell layer meet Eg 2 nd shell layer ＜Eg 3 rd shell layer 。
Alternatively, in some embodiments of the application, the n ranges from 1.ltoreq.n.ltoreq.5; preferably, n is 3.
Alternatively, in some embodiments of the application, the nanoparticle is selected from CdSe/CdS/CdZnS/ZnS, cdSe/CdS/CdZnS, cdZnSe/ZnSe/CdZnS/ZnSeS, cdZnSe/ZnSe/CdZnS/ZnS or CdZnS/ZnSe/CdZnS/ZnS.
Optionally, in some embodiments of the present application, in the second shell CdZnS of CdSe/CdS/CdZnS/ZnS, the molar amount of Cd is 22-27% of the total molar amount of Cd and Zn, the lattice mismatch degree of the core and the 1 st shell is 3.7-4.3%, the lattice mismatch degree of the 1 st shell and the 2 nd shell is 1.8-2.2%, and the lattice mismatch degree of the 2 nd shell and the 3 rd shell is 2.4-2.8%; and/or
In the second shell layer CdZnS of CdZnSe/ZnSe/CdZnS/ZnS, the molar quantity of Cd is 18-22% of the total molar quantity of Cd and Zn, the lattice mismatch degree of the core and the 1 st shell layer is 1.9-2.3%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 2.8-3.2%, and the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 2.4-2.7%; and/or
In the second shell layer CdZnS of CdZnS/ZnSe/CdZnS/ZnS, the molar quantity of Cd is 8-12% of the total molar quantity of Cd and Zn, the lattice mismatch degree of the core and the 1 st shell layer is 3.3-3.8%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 1.8-2.2%, and the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 1.4-1.8%.
Alternatively, in some embodiments of the application, the nanoparticle has a particle size in the range of 10 to 20nm.
Correspondingly, the embodiment of the application also provides a nanoparticle composition, which comprises a solvent, and the nanoparticle composition further comprises the nanoparticles.
Correspondingly, the embodiment of the application also provides a light-emitting diode, which comprises an anode, a light-emitting layer and a cathode which are sequentially stacked, wherein the light-emitting layer comprises the nano particles.
Optionally, in some embodiments of the present application, the anode and the cathode are respectively and independently selected from a doped metal oxide electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal simple substance electrode or an alloy electrode, wherein the material of the doped metal oxide electrode is selected from at least one of indium doped tin oxide, fluorine doped tin oxide, antimony doped tin oxide, aluminum doped zinc oxide, gallium doped zinc oxide, indium doped zinc oxide, magnesium doped zinc oxide and aluminum doped magnesium oxide, and the composite electrode is selected from AZO/Ag/AZO, AZO/Al/AZO, ITO/Ag /ITO、ITO/Al/ITO、ZnO/Ag/ZnO、ZnO/Al/ZnO、TiO 2 /Ag/TiO 2 、TiO 2 /Al/TiO 2 ZnS/Ag/ZnS or ZnS/Al/ZnS; the material of the metal simple substance electrode is at least one selected from Ag, al, au, pt, ca and Ba.
Correspondingly, the embodiment of the application also provides a display device which comprises the light emitting diode.
According to the application, the lattice mismatch degree between the adjacent shell layers of the nano particles is less than or equal to 5%, so that fewer interface defects exist between the adjacent shell layers in the nano particles, the formation of non-radiative recombination centers at the interface defects caused by lattice stress is reduced, the stability and fluorescence quantum efficiency of the nano particles are improved, and the luminous efficiency and the service life of the light-emitting diode prepared by using the nano particles are further improved. In addition, the light-emitting diode prepared by using the nano particles has higher carrier injection balance, thereby having higher luminous efficiency and longer service life.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a light emitting diode according to an embodiment of the present application;
FIG. 2 is a schematic diagram of another LED according to an embodiment of the present application;
FIG. 3 is a schematic view of another LED according to an embodiment of the present application;
FIG. 4 is a schematic diagram of another LED according to an embodiment of the present application;
fig. 5 is a schematic structural diagram of another led according to an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present application. Furthermore, it should be understood that the detailed description is presented herein for purposes of illustration and description only, and is not intended to limit the application.
In the present application, unless otherwise indicated, terms of orientation such as "upper" and "lower" are used to generally refer to the upper and lower positions of the device in actual use or operation, and specifically the orientation of the drawing figures; while "inner" and "outer" are for the outline of the device. In addition, in the description of the present application, the term "comprising" means "including but not limited to". The terms first, second, third and the like are used merely as labels, and do not impose numerical requirements or on the order of construction. The term "plurality" means "two or more".
Various embodiments of the application may exist in a range of forms; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the application; it is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.
The embodiment of the application provides a nanoparticle based on II-VI group elements, which comprises a core and at least two shell layers coated on the surface of the core, in other words, the nanoparticle comprises the core and n shell layers coated on the surface of the core, wherein the n shell layers are sequentially laminated, and in other words, the structure of the nanoparticle comprises the core/1 st shell layer/1 st shell layer/n shell layer. In the nano particle, the lattice mismatch degree between the adjacent shell layers is less than or equal to 5%.
The lattice mismatch degree between the adjacent shell layers in the nano particles is less than or equal to 5%, so that fewer interface defects exist between the core and the 1 st shell layer in the nano particles and between the adjacent shell layers, the non-radiative recombination center formed at the interface defect caused by lattice stress is reduced, the stability and fluorescence quantum efficiency of the nano particles are improved, and the luminous efficiency and the service life of the light emitting diode prepared by using the nano particles are further improved.
In some embodiments, the degree of lattice mismatch between the core and the 1 st shell layer of the nanoparticle is 5% or less. The nano particles have fewer interface defects between the core and the 1 st shell, so that non-radiative recombination centers are formed at the interface defects caused by lattice stress are reduced, the stability and fluorescence quantum efficiency of the nano particles are further improved, and the luminous efficiency and the service life of the light-emitting diode prepared by using the nano particles are further improved.
In some embodiments, n is an integer greater than or equal to 2, and the material of the 2 nd shell layer of the nanoparticle is CdZnS, which is favorable for hole injection into the core and limits (blocks) electron injection into the core, so that the carriers of radiative recombination luminescence injected into the core tend to be balanced, excessive electrons are prevented from entering the core to enable the nanoparticle to be in a charged state, non-radiative auger recombination is generated to quench, stability and fluorescence quantum efficiency of the nanoparticle are further improved, and light-emitting efficiency and service life of a light-emitting diode prepared by using the nanoparticle are further improved.
It can be understood that when the nanoparticle satisfies the combination of any two conditions of CdZnS, the stability and fluorescence quantum efficiency of the nanoparticle are improved more than when only one condition is satisfied, when the lattice mismatch degree between the adjacent shell layers is 5% or less, the lattice mismatch degree between the core and the 1 st shell layer is 5% or less, and the material of the 2 nd shell layer is CdZnS.
It can be understood that when the nanoparticle simultaneously satisfies that the lattice mismatch degree between the adjacent shell layers is 5% or less, the lattice mismatch degree between the core and the 1 st shell layer is 5% or less, and the material of the 2 nd shell layer is CdZnS, the effect of improving the stability and fluorescence quantum efficiency of the nanoparticle is better than that when only one condition is satisfied and any two conditions are satisfied.
In addition, the light emitting diode prepared by using the group II-VI element-based nanoparticle has higher carrier injection balance, thereby having higher luminous efficiency and longer service life.
It is understood that in at least one embodiment, the nanoparticle is a quantum dot.
In some embodiments, the band gap of the core ranges from 1.9 to 2.75eV, which may enable the nanoparticle to emit red, green or blue light with higher color purity.
In the 2 nd shell layer CdZnS, the molar quantity of Cd is 10-50% of the total molar quantity of Cd and Zn. Therefore, the forbidden bandwidth of the CdZnS of the 2 nd shell layer is 2-3 eV, so that the energy level difference between the valence band top of the 2 nd shell layer and the valence band top of the core is large, and the 2 nd shell layer has a strong binding effect on excitons in the core. When the Cd content is higher than the range, the band gap width of the 2 nd shell CdZnS is obviously narrowed, the binding effect on the nuclear exciton is weakened, and the fluorescence stability of the nanoparticle material is reduced; when the Cd content is lower than the range, the lattice mismatch degree between the 2 nd shell CdZnS and the 1 st shell is larger, so that the number of interface defect states is increased, and the fluorescent property of the nanoparticle material is poorer.
In at least one embodiment, the luminescence wavelength of the nanoparticle is 647-760 nm, in other words, the nanoparticle is a red nanoparticle, and the molar amount of Cd in the 2 nd shell CdZnS is 25-50% of the total molar amount of Cd and Zn. Therefore, the surface defect state of the red nano particles can be passivated more effectively, and the excitons in the nucleus are restrained, so that the excitons are prevented from being delocalized to the surface of the shell, and are captured and quenched by the defect state on the surface of the shell.
In at least one embodiment, the luminescent wavelength of the nanoparticle is 492-550 nm, in other words, the nanoparticle is a green nanoparticle, and the molar amount of Cd in the 2 nd shell CdZnS is 15-25% of the total molar amount of Cd and Zn. Therefore, the defect state on the surface of the green nano particle can be passivated more effectively, and the exciton in the nucleus is restrained, so that the exciton is prevented from being delocalized to the surface of the shell, and is captured and quenched by the defect state on the surface of the shell.
In at least one embodiment, the luminescence wavelength of the nanoparticle is 430-455 nm, in other words, the nanoparticle is a blue nanoparticle, and the molar amount of Cd in the 2 nd shell CdZnS is 10-25% of the total molar amount of Cd and Zn. Therefore, the defect state on the surface of the blue nano particle can be passivated more effectively, and the exciton in the nucleus is restrained, so that the exciton is prevented from being delocalized to the surface of the shell, and is captured and quenched by the defect state on the surface of the shell.
In some embodiments, when both Cd and Zn are included in the x-th shell layer and the x+1-th shell layer of the nanoparticle, where 1.ltoreq.x < n, then the ratio of the molar amount of Cd in the x+1-th shell layer relative to the total molar amount of Cd and Zn is less than the ratio of the molar amount of Cd in the x-th shell layer relative to the total molar amount of Cd and Zn. Therefore, the forbidden band width of the (x+1) th shell layer is larger than that of the (x) th shell layer, the conduction band bottom energy level of the (x+1) th shell layer is larger than that of the (x) th shell layer, and the valence band top energy level of the (x+1) th shell layer is larger than that of the (x) th shell layer, so that electrons and holes injected into the core can be further bound in the core, tunneling of carriers from the core to the surface of the (x+1) th shell layer is effectively inhibited, the possibility that excitons are captured and quenched by defect states on the surface of the nanoparticle is reduced, the lattice matching degree between adjacent core and shell layers and between adjacent shell layers is higher, the generation of interface defect states is eliminated, the surface defect states of the nanoparticle is fewer, the luminous efficiency of the nanoparticle is improved, and the luminous efficiency of the luminous diode prepared by using the nanoparticle is improved.
The forbidden band width Eg of the core and each shell layer of the nanoparticle meets Eg Nuclear ＜Eg 1 st shell layer ＜······＜Eg Nth shell layer In other words, the nanoparticlesThe nanoparticle is a Type I nanoparticle, in other words, the core of the nanoparticle and the conduction band bottom energy level and the valence band top energy level of each shell layer meet the Type I, in other words, the core of the nanoparticle and the conduction band bottom energy level of each shell layer gradually increase along the direction from the core to the outermost n-th shell layer, and the core of the nanoparticle and the valence band top energy level of each shell layer gradually decrease along the direction from the core to the outermost n-th shell layer. Therefore, electrons and holes injected into the core can be effectively bound in the core, carriers can be effectively restrained from tunneling from the core to the surface of the shell, the possibility that excitons are captured and quenched by a defect state on the surface of the nanoparticle is reduced, and therefore the luminous efficiency of the nanoparticle is improved, and the luminous efficiency of a light-emitting diode prepared by using the nanoparticle is further improved. In addition, the lattice matching degree between the adjacent cores and the shell layers and between the adjacent shell layers is higher, the generation of interface defect states is eliminated, the surface defect states of the nano particles are fewer, and the luminous efficiency and the service life of the light emitting diode prepared by the nano particles are further improved.
As an example, in some embodiments, the n is greater than 2, cd and Zn are contained in the 3 rd shell layer of the nanoparticle, the ratio of the Cd molar amount in the 3 rd shell layer to the total molar amount of Cd and Zn is less than the ratio of the Cd molar amount in the 2 nd shell layer to the total molar amount of Cd and Zn, and the forbidden band widths of the 2 nd and 3 rd shell layers satisfy Eg 2 nd shell layer ＜Eg 3 rd shell layer 。
In still other embodiments, the n is greater than 2, the material of the 3 rd shell of the nanoparticle is ZnS, and the forbidden bandwidths of the 2 nd shell and the 3 rd shell satisfy Eg 2 nd shell layer ＜Eg 3 rd shell layer 。
The core and the shell layers other than the 2 nd shell layer may each independently include but are not limited to at least one of Zn and Cd, and each independently include but are not limited to at least one of Te, se and S. Thus, the nano particles composed of the elements are based on the cores of II-VI elements, and the carrier injection of the light-emitting diode prepared from the nano particles tends to be balanced, so that the light-emitting diode has higher luminous efficiency and longer service life.
As an example, the material of the core and the material of the shell other than the 2 nd shell may be selected from, but not limited to CdSe, cdZnSe, cdS, cdTe, cdSeTe, cdZnS, cdZnSeS, znTe, cdSeS, znSe, znS or ZnSeS.
In some embodiments, the nanoparticle comprises a 3 rd shell layer, the material of the 3 rd shell layer is selected from CdZnS, znSe, znSeS or ZnS. The forbidden band width of the material is larger than that of the 2 nd shell CdZnS.
It can be understood that the core and the shell of the nanoparticle may be the same or different, so long as the nanoparticle is a Type I nanoparticle, i.e., so long as the forbidden bandwidth of each shell is ensured to satisfy Eg 1 st shell layer ＜······＜Eg Nth shell layer And (3) obtaining the product. When the materials of some two shells are the same, or the core is the same as the materials of some shells, the nano particles can meet the Type I by adjusting the proportion of elements in the materials.
The range of n is more than or equal to 1 and less than or equal to 5. The number of shell layers of the nano-particles is excessive, the preparation process is complex, more interfaces can be generated along with the increase of the number of shell layers, and meanwhile, the number of defects generated at the interfaces of the core and the shell layers and the interfaces of the shell layers can be increased due to the stress between lattices between different shell layers, so that the non-radiative composite energy loss of the nano-particles is increased.
In at least one embodiment, the number of shell layers of the nanoparticle is 3, that is, the nanoparticle includes 3 shell layers, so that the nanoparticle can be guaranteed to have a good water-oxygen blocking effect, and can have fewer interface defects, so that the nanoparticle has higher stability and fluorescence quantum efficiency at the same time, and a light emitting diode prepared by using the nanoparticle has higher luminous efficiency and longer service life.
As an example, the nanoparticle may be selected from red nanoparticle CdSe/CdS/CdZnS/ZnS, red nanoparticle CdSe/CdS/CdZnS, red nanoparticle CdZnSe/ZnSe/CdZnS/ZnSeS/ZnS, green nanoparticle CdZnSe/ZnSe/CdZnS/ZnS, or blue nanoparticle CdZnS/ZnSe/CdZnS/ZnS.
In some embodiments, the second shell CdZnS of the red nanoparticle CdSe/CdS/CdZnS/ZnS has a molar amount of Cd of 22-27% of the total molar amount of Cd and Zn, a lattice mismatch degree of the core and the 1 st shell of 3.7-4.3%, a lattice mismatch degree of the 1 st shell and the 2 nd shell of 1.8-2.2%, and a lattice mismatch degree of the 2 nd shell and the 3 rd shell of 2.4-2.8%.
In at least one embodiment, in the red nanoparticle CdSe/CdS/CdZnS/ZnS, the molar amount of Cd in the CdZnS of the second shell layer is 25% of the total molar amount of Cd and Zn, the lattice mismatch degree of the core and the 1 st shell layer is 3.9%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 2%, and the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 2.5%.
In some embodiments, the molar amount of Cd in the second shell layer CdZnSe/ZnSe/CdZnS/ZnS of the green nanoparticle is 18-22% of the total molar amount of Cd and Zn, the lattice mismatch degree of the core and the 1 st shell layer is 1.9-2.3%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 2.8-3.2%, and the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 2.4-2.7%.
In at least another embodiment, the green nanoparticle CdZnSe/ZnSe/CdZnS/ZnS has a molar amount of Cd in the second shell CdZnS of 20% of the total molar amount of Cd and Zn, a lattice mismatch degree of the core and the 1 st shell of 2%, a lattice mismatch degree of the 1 st shell and the 2 nd shell of 3%, and a lattice mismatch degree of the 2 nd shell and the 3 rd shell of 2.5%.
In some embodiments, the blue nanoparticle comprises a second shell layer CdZnS of CdZnS/ZnSe/CdZnS/ZnS, wherein the molar amount of Cd is 8-12% of the total molar amount of Cd and Zn, the lattice mismatch degree of the core and the 1 st shell layer is 3.3-3.8%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 1.8-2.2%, and the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 1.4-1.8%.
In at least yet another embodiment, the blue nanoparticle CdZnS/ZnSe/CdZnS/ZnS, wherein the molar amount of Cd in the second shell CdZnS is 10% of the total molar amount of Cd and Zn, the lattice mismatch of the core and the 1 st shell is 3.5%, the lattice mismatch of the 1 st shell and the 2 nd shell is 2%, and the lattice mismatch of the 2 nd shell and the 3 rd shell is 1.5%.
The adjacent cores and the shell layers of the nano-particles and the lattice mismatch degree between the adjacent shell layers are low, so that the nano-particles with larger particle size, unchanged interface defect state number and even smaller interface defect state number can be prepared through shell layer thickness control. In some embodiments, the nanoparticle has a particle size in the range of 10 to 20nm. In the particle size range, the problem of energy loss caused by energy resonance transfer effect due to too small spacing between the arranged and stacked nanoparticles after the nanoparticles are formed into a film, which leads to the reduction of the energy conversion efficiency of the nanoparticles, can be effectively reduced, and the nanoparticles are uniform in size and have proper half-peak width, so that the fluorescence quantum efficiency of the nanoparticles is improved, and the luminous efficiency of the light-emitting diode prepared by using the nanoparticles is further improved.
The embodiment of the application also provides a nanoparticle composition, which comprises the nanoparticle and a solvent. Wherein the solvent is a solvent known in the art for dispersing the nanoparticles, such as n-octane, etc.
In some embodiments, the concentration of the nanoparticles in the nanoparticle composition ranges from 8 to 50mg/ml. If the concentration is too low, the problems of leakage and the like caused by the fact that the light-emitting layer after film formation is not compact are easily caused; if the concentration is too high, the composition tends to agglomerate, and the film layer formed is too thick.
Referring to fig. 1, an embodiment of the present application further provides a light emitting diode 100, which includes an anode 10, a light emitting layer 20, and a cathode 30 sequentially stacked. The light emitting layer 20 includes the nanoparticles described above.
Referring to fig. 2, in an embodiment, the light emitting diode 100 further includes a hole transport layer 40 between the anode 10 and the light emitting layer 20. In other words, the light emitting diode 100 includes an anode 10, a hole transport layer 40, a light emitting layer 20, and a cathode 30, which are sequentially stacked.
Referring to fig. 3, in one embodiment, the led 100 further includes an electron transport layer 50 between the light emitting layer 20 and the cathode 30. In other words, the light emitting diode 100 includes an anode 10, a light emitting layer 20, an electron transport layer 50, and a cathode 30, which are sequentially stacked.
Referring to fig. 4, in an embodiment, the light emitting diode 100 includes an anode 10, a hole transporting layer 40, a light emitting layer 20, an electron transporting layer 50, and a cathode 30 sequentially stacked.
Referring to fig. 5, in one embodiment, the light emitting diode 100 further includes a hole injection layer 60 between the anode 10 and the hole transport layer 40. In other words, the light emitting diode 100 includes an anode 10, a hole injection layer 60, a hole transport layer 40, a light emitting layer 20, an electron transport layer 50, and a cathode 30, which are sequentially stacked.
The anode 10 and the cathode 30 are known in the art as an anode and a cathode for a light emitting diode, and may be, for example, independently selected from, but not limited to, a doped metal oxide electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal simple electrode, or an alloy electrode, respectively. The material of the doped metal oxide electrode may be selected from at least one of indium doped tin oxide (ITO), fluorine doped tin oxide (FTO), antimony doped tin oxide (ATO), aluminum doped zinc oxide (AZO), gallium doped zinc oxide (GZO), indium doped zinc oxide (IZO), magnesium doped zinc oxide (MZO), and aluminum doped magnesium oxide (AMO), but is not limited thereto. The composite electrode is a composite electrode comprising doped or undoped transparent metal oxide and metal sandwiched therebetween, such as AZO/Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, znO/Ag/ZnO, znO/Al/ZnO, and TiO 2 /Ag/TiO 2 、TiO 2 /Al/TiO 2 ZnS/Ag/ZnS, znS/Al/ZnS, etc. The material of the metal simple substance electrode can be selected from at least one of Ag, al, au, pt, ca and Ba, but is not limited to.
The material of the hole transport layer 40 may also be a material known in the art for a hole transport layer, for example, may be selected from, but not limited to, poly [ bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine ] (PTAA), 2', 7' -tetrakis [ N, N-bis (4-methoxyphenyl) amino ] -9,9 '-spirobifluorene (spiro-omeTAD), 4' -cyclohexylbis [ N, N-bis (4-methylphenyl) aniline ] (TAPC), N, at least one of N '-bis (1-naphthyl) -N, N' -diphenyl-1, 1 '-diphenyl-4, 4' -diamine (NPB), 4 '-bis (N-carbazole) -1,1' -biphenyl (CBP), poly [ (9, 9-dioctylfluorenyl-2, 7-diyl) -co- (4, 4'- (N- (p-butylphenyl)) diphenylamine) ] (TFB), poly (9-vinylcarbazole) (PVK), polytrianiline (Poly-TPD), and 4,4',4 "-tris (carbazol-9-yl) triphenylamine (TCTA).
The material of the electron transport layer 50 is a material known in the art for an electron transport layer, and may be, for example, one or more selected from, but not limited to, metal oxides, doped metal oxides, group 2-6 semiconductor materials, group 3-5 semiconductor materials, and group 1-3-6 semiconductor materials. In particular, the metal oxide may be selected from, but not limited to, znO, tiO 2 、SnO 2 、Al 2 O 3 One or more of the following; the metal oxide in the doped metal oxide can be selected from, but not limited to, znO, tiO 2 、SnO 2 The doping element can be selected from one or more of Al, mg, li, in, ga, and as an example, the doping metal oxide can be Aluminum Zinc Oxide (AZO), lithium Zinc Oxide (LZO), magnesium Zinc Oxide (MZO) and the like; the 2-6 semiconductor family material may be selected from, but is not limited to, one or more of ZnS, znSe, cdS; the 3-5 semiconductor family material may be selected from, but is not limited to, at least one of InP, gaP; the group 1-3-6 semiconductor material may be selected from, but is not limited to, at least one of CuInS, cuGaS.
The material of the hole injection layer 60 may also be a material known in the art for hole injection layers, such as may be selected from but not limited to 2,3,6,7,10, 11-hexacyano-1, 4,5,8,9, 12-hexaazabenzophenanthrene (HAT-CN), PEDOT: PSS doped with s-MoO 3 Derivatives of (PEDOT: PSS: s-MoO) 3 ) At least one of nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.
It will be appreciated that the led 100 may further include functional layers conventionally used in leds to help improve led performance, such as an electron blocking layer, a hole blocking layer, an electron injection layer, an interface modification layer, and the like.
It is understood that the materials of the layers of the led 100 may be adjusted according to the light emitting requirements of the led 100.
It is understood that the light emitting diode 100 may be a front-mounted light emitting diode or an inverted light emitting diode.
The light emitting layer 20 of the light emitting diode 100 includes the nanoparticles of the present application, thereby having high light emitting efficiency and long lifetime.
The application also relates to a display device comprising the light emitting diode 100.
The present application will now be described in more detail by way of the following examples, which are intended to be illustrative of the application and not limiting thereof.
Example 1
Providing an ITO anode 10 having a thickness of 30 nm;
spin coating PEDOT on the anode 10: PSS material is annealed at 100 ℃ for 15min to obtain a hole injection layer 60 with the thickness of 20 nm;
spin-coating a TFB material on the hole injection layer 60, and annealing at 100 ℃ for 15min to obtain a hole transport layer 40 with a thickness of 15 nm;
synthesizing core CdSe, growing 1 st shell CdS on the surface of the core, growing 2 nd shell CdZnS on the surface of the 1 st shell, wherein the molar quantity of Cd in the 2 nd shell is 40% of the total molar quantity of Cd and Zn, and growing 3 rd shell ZnS on the surface of the 2 nd shell to obtain red nano particles CdSe/CdS/CdZnS/ZnS, wherein the wavelength of the core is 632nm, the lattice mismatch degree of the core and the 1 st shell is 3.9%, the lattice mismatch degree of the 1 st shell and the 2 nd shell is 2%, the lattice mismatch degree of the 2 nd shell and the 3 rd shell is 2.5%, and the forbidden bandwidths of the core, the 1 st shell, the 2 nd shell and the 3 rd shell are 2.2eV, 2.49eV, 2.93eV and 3.61eV respectively;
Dispersing the red nano-particles CdSe/CdS/CdZnS/ZnS in an n-octane solvent to obtain a nano-particle composition, and spin-coating the nano-particle composition on the hole transport layer 40 to obtain a light-emitting layer 20 with a thickness of 15 nm;
spin-coating an ethanol solution of ZnO on the light emitting layer 20 to obtain an electron transport layer 50 having a thickness of 40 nm;
evaporating Ag on the electron transport layer 50 to obtain a cathode with the thickness of 80 nm;
and packaging to obtain the light emitting diode 100.
Example 2
This embodiment is substantially the same as embodiment 1, except that the light emitting layer 20 of this embodiment is prepared by:
synthesizing nuclear CdZnSe, growing a 1 st shell layer ZnSe on the surface of the nuclear, growing a 2 nd shell layer CdZnS on the surface of the 1 st shell layer, wherein the molar quantity of Cd in the 2 nd shell layer is 20% of the total molar quantity of Cd and Zn, and growing a 3 rd shell layer ZnS on the surface of the 2 nd shell layer to obtain green nano-particles CdZnSe/ZnSe/CdZnS/ZnS, wherein the wavelength of the nuclear is 535nm, the lattice mismatch degree of the nuclear and the 1 st shell layer is 2%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 3%, the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 2.5%, and the forbidden band widths of the nuclear, the 1 st shell layer, the 2 nd shell layer and the 3 rd shell layer are 2.32eV, 2.69eV and 3.61eV respectively;
Dispersing the green nano particles CdZnSe/ZnSe/CdZnS/ZnS in an n-octane solvent to obtain a nano particle composition, and spin-coating the nano particle composition on the hole transport layer 40 to obtain the light emitting layer 20 with the thickness of 20 nm.
Example 3
This embodiment is substantially the same as embodiment 1, except that the light emitting layer 20 of this embodiment is prepared by:
synthesizing nuclear CdZnS, growing 1 st shell ZnSe on the surface of the nuclear, and growing 2 nd shell CdZnS on the surface of the 1 st shell, wherein the molar quantity of Cd in the 2 nd shell is 10% of the total molar quantity of Cd and Zn; growing a 3 rd shell layer ZnS on the surface of a 2 nd shell layer to obtain blue nano particles CdZnS/ZnSe/CdZnS/ZnS, wherein in the blue nano particles CdZnS/ZnSe/CdZnS/ZnS, the wavelength of a core is 470nm, the lattice mismatch degree of the core and the 1 st shell layer is 3.5%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 2%, the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 1.5%, and the forbidden band widths of the core, the 1 st shell layer, the 2 nd shell layer and the 3 rd shell layer are 2.64eV, 2.69eV, 3.4eV and 3.61eV respectively;
dispersing the blue nano-particles CdZnS/ZnSe/CdZnS/ZnS in an n-octane solvent to obtain a nano-particle composition, and spin-coating the nano-particle composition on the hole transport layer 40 to obtain the light emitting layer 20 with a thickness of 25 nm.
Example 4
This embodiment is substantially the same as embodiment 1, except that the light emitting layer 20 of this embodiment is prepared by:
synthesizing nuclear CdSe, and growing a 1 st shell CdS on the surface of the nuclear; growing a 2 nd shell CdZnS on the surface of a 1 st shell to obtain red nano particles CdSe/CdS/CdZnS, wherein in the red nano particles CdSe/CdS/CdZnS, the wavelength of a core is 620nm, the lattice mismatch degree of the core and the 1 st shell is 3.6%, the lattice mismatch degree of the 1 st shell and the 2 nd shell is 2%, and the forbidden bandwidths of the core, the 1 st shell and the 2 nd shell are 2.3eV, 2.49eV and 3.1eV respectively;
dispersing the red nano-particles CdSe/CdS/CdZnS in an n-octane solvent to obtain a nano-particle composition, and spin-coating the nano-particle composition on the hole transport layer 40 to obtain the luminescent layer 20 with the thickness of 10 nm.
Example 5
This embodiment is substantially the same as embodiment 1, except that the light emitting layer 20 of this embodiment is prepared by:
synthesizing core CdZnSe, growing 1 st shell ZnSe on the surface of the core, growing 2 nd shell CdZnS on the surface of the 1 st shell, wherein the molar quantity of Cd in the 2 nd shell is 30% of the total molar quantity of Cd and Zn, growing 3 rd shell ZnSeS on the surface of the 2 nd shell, the molar quantity of Se in the 3 rd shell is 20% of the total molar quantity of Se and S, and growing 4 th shell ZnS on the surface of the 3 rd shell to obtain red nano-particle CdZnSe/ZnSe/ZnSeS/ZnS, wherein the wavelength of the core is 625nm, the lattice mismatch degree of the core and the 1 st shell is 2.5%, the lattice mismatch degree of the 1 st shell and the 2 nd shell is 2%, the lattice mismatch degree of the 2 nd shell and the 3 rd shell is 2.2%, the lattice mismatch degree of the 3 rd shell and the 4 th shell is 3%, and the band gap widths of the core, the 1 st, the 2 nd, the 3 rd and 4 th shells are 1.98eV, 3.61eV and 3.61.61.5.ev respectively - ；
Dispersing the red nano-particles CdZnSe/ZnSe/CdZnS/ZnSeS/ZnS in an n-octane solvent to obtain a nano-particle composition, and spin-coating the nano-particle composition on the hole transport layer 40 to obtain the light emitting layer 20 with a thickness of 15 nm.
Example 6
This example is substantially the same as example 1, except that the molar amount of Cd in the 2 nd shell layer of the red nanoparticle CdSe/CdS/CdZnS/ZnS in this example is 25% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 3.15eV.
Example 7
This example is substantially the same as example 1, except that the molar amount of Cd in the 2 nd shell layer of the red nanoparticle CdSe/CdS/CdZnS/ZnS in this example is 50% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 2.85eV.
Example 8
This example is substantially the same as example 1, except that the molar amount of Cd in the 2 nd shell layer of the red nanoparticle CdSe/CdS/CdZnS/ZnS in this example is 20% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 3.2eV.
Example 9
This example is substantially the same as example 1, except that the molar amount of Cd in the 2 nd shell layer of the red nanoparticle CdSe/CdS/CdZnS/ZnS in this example is 60% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 2.75eV.
Example 10
This example is substantially the same as example 2, except that the molar amount of Cd in the 2 nd shell layer of the green nanoparticle CdZnSe/ZnSe/CdZnS/ZnS in this example is 15% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 3.3eV.
Example 11
This example is substantially the same as example 2, except that the molar amount of Cd in the 2 nd shell layer of the green nanoparticle CdZnSe/ZnSe/CdZnS/ZnS in this example is 25% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 3.15eV.
Example 12
This example is substantially the same as example 2, except that the molar amount of Cd in the 2 nd shell layer of the green nanoparticle CdZnSe/ZnSe/CdZnS/ZnS in this example is 10% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 3.4eV.
Example 13
This example is substantially the same as example 2, except that the molar amount of Cd in the 2 nd shell layer of the green nanoparticle CdZnSe/ZnSe/CdZnS/ZnS in this example is 35% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 2.98eV.
Example 14
This example is substantially the same as example 3, except that the molar amount of Cd in the 2 nd shell layer of the blue nanoparticle CdZnS/ZnSe/CdZnS/ZnS in this example is 25% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 3.5eV.
Example 15
This example is substantially the same as example 3, except that the molar amount of Cd in the 2 nd shell layer of the blue nanoparticle CdZnS/ZnSe/CdZnS/ZnS in this example is 15% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 3.3eV.
Example 16
This example is substantially the same as example 3, except that the molar amount of Cd in the 2 nd shell layer of the blue nanoparticle CdZnS/ZnSe/CdZnS/ZnS in this example is 3% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 3.58eV.
Example 17
This example is substantially the same as example 3, except that the molar amount of Cd in the 2 nd shell layer of the blue nanoparticle CdZnS/ZnSe/CdZnS/ZnS in this example is 30% of the total molar amount of Cd and Zn, and the forbidden band width of the 2 nd shell layer is 3.2eV.
Comparative example 1
This comparative example is substantially the same as example 1, except that the material of the light emitting layer 20 of this comparative example is red nanoparticle CdSe/CdS, in which the lattice mismatch degree of the core and the 1 st shell is 3.6%, and the forbidden bandwidths of the core and the 1 st shell are 1.99eV and 2.49eV, respectively.
Comparative example 2
This comparative example is substantially the same as example 2 except that the material of the light emitting layer 20 of this comparative example is green nanoparticle CdZnSe/CdZnS/ZnS, in which the lattice mismatch degree of the core and the 1 st shell layer is 3.6%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 2.5%, and the forbidden bandwidths of the core, the 1 st shell layer, and the 2 nd shell layer are 2.45eV, 2.8eV, and 3.61eV, respectively.
Comparative example 3
This comparative example is substantially the same as example 3 except that the material of the light emitting layer 20 of this comparative example is blue nanoparticle CdZnSe/CdZnS/ZnS, in which the lattice mismatch degree of the core and the 1 st shell layer is 2%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 1.8%, and the forbidden bandwidths of the core, the 1 st shell layer, and the 2 nd shell layer are 2.75eV, 3.3eV, and 3.61eV, respectively.
Comparative example 4
This comparative example is substantially the same as example 1 except that the material of the light emitting layer 20 of this comparative example is red nanoparticle CdSe/ZnS, in which the lattice mismatch degree of the core and 1 st shell layer is 10.6%, and the forbidden bandwidths of the core and 1 st shell layer are 1.95eV and 3.61eV, respectively.
Comparative example 5
This comparative example is substantially the same as example 2, except that the material of the light emitting layer 20 of this comparative example is green nanoparticle CdZnSeS/ZnSe/ZnS, in which the degree of lattice mismatch of the core and the 1 st shell is 6.3%, the degree of lattice mismatch of the 1 st shell and the 2 nd shell is 4%, and the forbidden bandwidths of the core, the 1 st shell, and the 2 nd shell are 2.32eV, 2.7eV, and 3.61eV, respectively.
Comparative example 6
This comparative example is substantially the same as example 3 except that the material of the light emitting layer 20 of this comparative example is blue nanoparticle CdZnS/ZnSeS/ZnS, in which the lattice mismatch degree of the core and the 1 st shell layer is 5.5%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 2.5%, and the forbidden bandwidths of the core, the 1 st shell layer, and the 2 nd shell layer are 2.63eV, 2.9eV, and 3.61eV, respectively.
The fluorescent quantum efficiencies PLQY and particle diameters of the nanoparticles of examples 1 to 17 and comparative examples 1 to 6 were measured, respectively. The fluorescent nanoparticle efficiency test adopts an Edinburgh FS5 SC-30 fluorescence spectrophotometer test; the particle size was measured by a Transmission Electron Microscope (TEM). The detection results are shown in the table I.
The light emitting diodes of examples 1 to 17 and comparative examples 1 to 6 were examined for electron injection property, hole injection property, emission peak of emitted light (EL patch), full width at half maximum (FWHM), external Quantum Efficiency (EQE), and lifetime t95@1knit. The electron injection performance and the hole injection performance are measured by a conventional carrier injection performance test method: the difference of electron and hole injection properties was tested by the semiconductor devices (single carrier transport thin film devices HOD/EOD) of the light emitting diodes of examples 1 to 17 and comparative examples 1 to 6, and the current density of the trap space charge limited current region in the curve of the complete single carrier device was selected as a comparison parameter to obtain the electron injection properties and hole injection properties of the semiconductor devices; the emission peak, half-peak width and external quantum efficiency EQE of the light-emitting diode are obtained by testing and calculating a Keithley 2400 high-precision digital source meter, an Ocean optics USB2000+ spectrometer and an LS-160 brightness meter; the test method of the service life T95@1knit is that the time for which the initial brightness of the device is attenuated to 95% is reduced under a constant current of 2mA, and the aging time is converted into a value of 1000 nit. The detection results are shown in the table I.
Table one:
from Table one can see:
the nanoparticles of examples 1-2, 4-13 have a larger particle size and a higher fluorescence quantum efficiency than the nanoparticles of comparative examples 1-2, 4-5; the nanoparticles of examples 3, 14-17 have a larger particle size and higher fluorescence quantum efficiency than the nanoparticles of comparative examples 3 and 6. Therefore, the material of the 2 nd shell layer is CdZnS, and the nano particles with the lattice mismatch degree between the core and the 1 st shell layer and between the adjacent shell layers being less than or equal to 5 percent have larger particle size and higher fluorescence quantum efficiency.
Compared with the light emitting diodes of comparative examples 1-2 and 4-5, the light emitting diodes of examples 1-2 and 4-13 have more balanced injection of electrons and holes, higher luminous efficiency and longer lifetime; the light emitting diodes of examples 3, 14-17 have a more balanced electron and hole injection, higher light emitting efficiency and longer lifetime than the nanoparticles of comparative examples 3 and 6. Therefore, the light-emitting diode prepared from the nano particles with the material of the 2 nd shell layer of the application being CdZnS and the lattice mismatch degree between the core and the 1 st shell layer and between the adjacent shell layers being less than or equal to 5 percent has higher luminous efficiency and longer service life.
The light emitting diode of example 1 has higher light emitting efficiency and longer lifetime than the light emitting diodes of examples 4 to 5. It can be seen that the light emitting diode having the 3-layer shell layer has higher luminous efficiency and longer life.
The light emitting diodes of examples 1, 6, and 7 have higher luminous efficiency and longer lifetime than the light emitting diodes of examples 8 to 9. Therefore, when the molar quantity of Cd in the second shell layer of the red nano-particles is 25-50% of the total molar quantity of Cd and Zn, the prepared light-emitting diode has higher luminous efficiency and longer service life.
The light emitting diodes of examples 2, 10, and 11 have higher luminous efficiency and longer lifetime than the light emitting diodes of examples 12 to 13. It can be seen that the second shell of the green nanoparticle has higher luminous efficiency and longer life when the molar amount of Cd in the second shell is 15-25% of the total molar amount of Cd and Zn.
The light emitting diodes of examples 3, 14, and 15 have higher luminous efficiency and longer lifetime than the light emitting diodes of examples 16 to 17. It can be seen that the blue nanoparticle has higher luminous efficiency and longer service life when the molar amount of Cd in the second shell layer is 10-25% of the total molar amount of Cd and Zn.
The foregoing has outlined rather broadly the nano-particles, nano-particle compositions and light emitting diodes provided by the present examples, which are provided herein to illustrate the principles and embodiments of the present application and to provide an additional understanding of the methods and concepts of the present application; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in light of the ideas of the present application, the present description should not be construed as limiting the present application.

Claims (17)

1. A nanoparticle characterized by: the nanoparticle structure comprises a core/1 st shell/nth shell, and lattice mismatch degree between adjacent shells is less than or equal to 5%.
2. The nanoparticle of claim 1, wherein: the lattice mismatch degree between the core and the 1 st shell layer is less than or equal to 5 percent.
3. The nanoparticle of claim 1 or 2, wherein: and n is an integer greater than or equal to 2, and the material of the 2 nd shell layer of the nano particle is CdZnS.
4. A nanoparticle according to claim 3, wherein: in the 2 nd shell layer CdZnS, the molar quantity of Cd is 10-50% of the total molar quantity of Cd and Zn.
5. A nanoparticle according to claim 3, wherein: the luminescence wavelength of the nano particles is 647-760 nm, and the molar quantity of Cd in the 2 nd shell layer CdZnS is 25-50% of the total molar quantity of Cd and Zn; or alternatively
The luminescence wavelength of the nano particles is 492-550 nm, and the molar quantity of Cd in the 2 nd shell layer CdZnS is 15-25% of the total molar quantity of Cd and Zn; or alternatively
The luminescence wavelength of the nano particles is 430-455 nm, and the molar quantity of Cd in the 2 nd shell layer CdZnS is 10-25% of the total molar quantity of Cd and Zn.
6. The nanoparticle of claim 1, wherein: the range of forbidden band width of the core is 1.9-2.75 eV; and/or
The forbidden band width Eg of the core and each shell layer satisfies the following conditions: eg Nuclear ＜Eg 1 st shell layer ＜……＜Eg Nth shell layer 。
7. A nanoparticle according to claim 3, wherein: the core and the shell layers except the 2 nd shell layer respectively and independently contain at least one of Zn and Cd, and respectively and independently contain at least one of Te, se and S.
8. A nanoparticle according to claim 3, wherein: the x-th shell layer and the x+1-th shell layer of the nano particle simultaneously contain Cd and Zn, wherein x is more than or equal to 1 and less than n, the ratio of the Cd molar quantity in the x+1-th shell layer to the total molar quantity of Cd and Zn is smaller than the ratio of the Cd molar quantity in the x-th shell layer to the total molar quantity of Cd and Zn, and the forbidden band width Eg of the core and each shell layer meets Eg Nuclear ＜Eg 1 st shell layer ＜……＜Eg Nth shell layer 。
9. A nanoparticle according to claim 3, wherein: the n is more than 2, the 3 rd shell layer of the nano particle comprises Cd and Zn, the ratio of the Cd molar quantity in the 3 rd shell layer to the total molar quantity of Cd and Zn is smaller than the ratio of the Cd molar quantity in the 2 nd shell layer to the total molar quantity of Cd and Zn, and the forbidden band widths of the 2 nd shell layer and the 3 rd shell layer meet Eg 2 nd shell layer ＜Eg 3 rd shell layer The method comprises the steps of carrying out a first treatment on the surface of the Or alternatively
The n is more than 2, the material of the 3 rd shell layer of the nano particle is ZnS, and the forbidden bandwidths of the 2 nd shell layer and the 3 rd shell layer meet Eg 2 nd shell layer ＜Eg 3 rd shell layer 。
10. A nanoparticle according to claim 3, wherein: n is more than or equal to 1 and less than or equal to 5; preferably, n is 3.
11. The nanoparticle of claim 1, wherein: the nanoparticle is selected from CdSe/CdS/CdZnS/ZnS, cdSe/CdS/CdZnS, cdZnSe/ZnSe/CdZnS/ZnSeS/ZnS, cdZnSe/ZnSe/CdZnS/ZnS or CdZnS/ZnSe/CdZnS/ZnS.
12. The nanoparticle of claim 11, wherein: in the CdSe/CdS/CdZnS/ZnS second shell layer CdZnS, the molar quantity of Cd is 22-27% of the total molar quantity of Cd and Zn, the lattice mismatch degree of the core and the 1 st shell layer is 3.7-4.3%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 1.8-2.2%, and the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 2.4-2.8%; and/or
In the second shell layer CdZnS of CdZnSe/ZnSe/CdZnS/ZnS, the molar quantity of Cd is 18-22% of the total molar quantity of Cd and Zn, the lattice mismatch degree of the core and the 1 st shell layer is 1.9-2.3%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 2.8-3.2%, and the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 2.4-2.7%; and/or
In the second shell layer CdZnS of CdZnS/ZnSe/CdZnS/ZnS, the molar quantity of Cd is 8-12% of the total molar quantity of Cd and Zn, the lattice mismatch degree of the core and the 1 st shell layer is 3.3-3.8%, the lattice mismatch degree of the 1 st shell layer and the 2 nd shell layer is 1.8-2.2%, and the lattice mismatch degree of the 2 nd shell layer and the 3 rd shell layer is 1.4-1.8%.
13. The nanoparticle of claim 1, wherein: the particle size of the nano particles ranges from 10 nm to 20nm.
14. A nanoparticle composition comprising a solvent, characterized in that: the nanoparticle composition further comprises the nanoparticle of any one of claims 1-13.
15. A light emitting diode comprising an anode, a light emitting layer and a cathode, which are laminated in sequence, characterized in that: the light emitting layer comprising the nanoparticle of any one of claims 1-13.
16. As claimed in claim 15Is characterized in that: the anode and the cathode are respectively and independently selected from at least one of doped metal oxide electrode, composite electrode, graphene electrode, carbon nano tube electrode, metal simple substance electrode or alloy electrode, the material of the doped metal oxide electrode is selected from indium doped tin oxide, fluorine doped tin oxide, antimony doped tin oxide, aluminum doped zinc oxide, gallium doped zinc oxide, indium doped zinc oxide, magnesium doped zinc oxide and aluminum doped magnesium oxide, and the composite electrode is selected from AZO/Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, znO/Ag/ZnO, znO/Al/ZnO and TiO 2 /Ag/TiO 2 、TiO 2 /Al/TiO 2 ZnS/Ag/ZnS or ZnS/Al/ZnS; the material of the metal simple substance electrode is at least one selected from Ag, al, au, pt, ca and Ba.
17. A display device, characterized in that: the display device comprising the light emitting diode according to any one of claims 15 to 16.
CN202210153051.2A 2022-02-18 2022-02-18 Nanoparticle, nanoparticle composition, light emitting diode, and display device Pending CN116656337A (en)

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