CA3186761A1

CA3186761A1 - Carbon quantum dot and synthesis method therefor, thin film and electronic device

Info

Publication number: CA3186761A1
Application number: CA3186761A
Authority: CA
Inventors: Yunjun Wang; Wei ZHAI; Dongqiang LIU
Original assignee: Suzhou Xingshuo Nanotech Co Ltd
Current assignee: Suzhou Xingshuo Nanotech Co Ltd
Priority date: 2020-06-12
Filing date: 2020-11-18
Publication date: 2021-12-16
Also published as: CN111808602B; WO2021248830A1; CN111808602A

Abstract

Provided are a carbon quantum dot, a synthesis method therefor, a thin film and an electronic device, the carbon quantum dot containing a structure represented by formula (2). In formula (2), L is a group represented by formula (1): in formula (1), R1, R2, R4, R5, R7 and R8 are each independently selected from a group consisting of the following groups: hydrogen, alkyl, amino, carboxyl, hydroxyl, nitryl, sulfonyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, haloalkyl, haloalkoxy, phosphino, and combinations thereof; R3, R6 and R9 are each independently selected from a group consisting of the following groups: substituted or unsubstituted hydroxyl, amino, ethylamino, diethylamino, benzoate, hydroxybenzoate and ethyl benzoate. The carbon quantum dot provided is high in fluorescence quantum yield, good in stability and narrow in half-peak width, and may be used in films and electronic devices.

Description

CARBON QUANTUM DOT AND SYNTHESIS METHOD THEREFOR, THIN
FILM AND ELECTRONIC DEVICE
Technical Field The present disclosure relates to the technical field of nanomaterials, and specifically relates to a carbon quantum dot and a synthesis method therefor, a thin film, and an electronic device.
Background As an important carbon-based nanomaterial, carbon quantum dots play an important role in analysis and detection, disease diagnosis, environmental monitoring, bioimaging, and optoelectronic device manufacture and other aspects. However, the diversity of synthesis raw materials and synthesis modes of the carbon quantum dots, and some uncertain factors in the reaction process led to large differences in compositions, morphologies, structures and properties of the carbon quantum dots. Therefore, a luminescence mechanism of the carbon quantum dots is still in the stage of speculation due to the uncertainty of the concept of luminescence caused by the uncertainty of its structure. Therefore, the in-depth study of preparation methods for the carbon quantum dots and the preferable selection of suitable raw materials are of great significance for the development of a controllable synthesis mode.
The raw material process used in an existing synthesis method of a carbon quantum dot material is often difficult to obtain a carbon quantum dot with higher purity, and there are problems that a more complicated purification process is required, and the carbon quantum dot obtained finally is relatively large in half-peak width, and relatively low in fluorescence quantum yield and the like.
Summary In view of the above technical problems, the present disclosure provides a carbon quantum dot, containing a structure represented by the following Formula (2):
4Lp4T)m _______________________________________ in Formula (2) In Formula (2), L is a group represented by the following Formula (1):

Date Recue/Date Received 2022-12-09 R8 R9 Ri Formula (1) In Formula (1), R1, R2, R4, R5, R7 and R8 are each independently selected from a group consisting of the following groups: hydrogen, alkyl, amino, carboxyl, hydroxyl, nifty!, sulfonyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, haloalkyl, haloalkoxy, phosphino, and combinations thereof; R3, R6 and R9 are each independently selected from a group consisting of the following groups: substituted or unsubstituted hydroxyl, amino, ethylamino, diethylamino, benzoate, hydroxybenzoate and ethyl benzoate.
T is independently selected from a group consisting of the following groups: a multi-carboxylic acid group, a polyol hydroxyl group, a polyphenol hydroxyl group, a polyamine group, a multi-boronic acid group, a multi-aldehyde group, a multi-benzonitrile group, and a polyhydrazide group.
Each of p, m, and n is a positive integer, while p is 2 or more, a plurality of L is the same or different respectively, and while m is 2 or more, a plurality of T is the same or different respectively.
In the carbon quantum dot of the present invention, the L group is a light-emitting group, the T group is a cross-linking group, and the light-emitting group and the cross-linking group are linked to each other. The cross-linking group of the present disclosure may significantly reduce the steric hindrance of the carbon quantum dot, and at the same time, the cross-linking group shows different electronegativity in different environments, so that it may be combined with the light-emitting group better, and the stability of the carbon quantum dot obtained is significantly enhanced.
It should be noted that, in the above Formula (2), it represents that a plurality of L and a plurality of T are linked, and a linkage position is not limited, as long as the linkage of a chemical bond is formed. For the group represented by "L", its linkage site is any position in which a monomer represented by Formula (1) may form a half bond. Similarly, for the group represented by "T", its linkage site is any position in which the multi-carboxylic acid group, the polyol hydroxyl group, the polyphenol hydroxyl group, the polyamine group, the multi-boronic acid group, the multi-aldehyde group, the multi-benzonitrile group, and the polyhydrazide group form a single bond.
Further, Formula (1) is selected from groups represented by the following structures:

2 Date Regue/Date Received 2022-12-09 Formula (1-1) Formula (1-2) Formula (1-3) Further, Formula (1) is selected from groups represented by the following structures:
----OH OH

Formula (1-4) Formula (1-5)

3 Date Regue/Date Received 2022-12-09 OH
Ii (ULOCOOH

<\.
Formula (1-6) Formula (1-7) OH
OH

Formula (1-8) Formula (1-9) 410 =-=, 7"--N

Formula (1-10) Formula (1-11) C _____________________________________________________________ 0 __ CH3 OH

N

Formula (1-12) Formula (1-13)

4 Date Recue/Date Received 2022-12-09 Formula (1-14).
Further, the T group is independently selected from a group consisting of the following groups:
groups represented by an oxalic acid, a malonic acid, a terephthalic acid, a tricarballylic acid, and a citric acid; groups represented by an ethylene glycol, a propylene glycol, a glycerol, and a hexanetriol; and groups represented by the following structural formulas:
Ng 011 Ivo , HO-4r . caN
HO
Kr ON 411.--C114-011 1101¨
Formula (2-1) Formula (2-2) I . -.4 --. 01-1 HO, OH
'OH HO
Formula (2-3) Formula (2-4) OH
OH

OH HO OH
Formula (2-5) Formula (2-6) Ht,.., Y õNit, HMLa .7,,,Cr' 012N maaN i 64 'NH2 Formula (2-7) Formula (2-8) Formula (2-9)

5 Date Recue/Date Received 2022-12-09 Hit .N, PIN
); -r "T Hi* 'Efr lift N., N
'1.
Wiz Nila HIN-Nt12 Formula (2-10) Formula (2-11) Formula (2-12) Formula (2-13) liallai Nii-lat*I1 Formula (2-14) Formula (2-15) lisP, Pitif NH
,e a ic..i...iko ...,.? 0 o1214. MA 'NF151 Formula (2-16) Formula (2-17) PIG:12B
mho 4.t...e.v=s,,,-,(7:,==orai,, itiokilytk.,-Biallb 4,4,0,01 tO 0 k-vb 0110)2 , .. atm%
Formula (2-18) Formula (2-19) Formula (2-20) WWI -r-S---n 'rni\--11"141 Oirhipr-Cm , 0,4-11(01,1 Formula (2-21) Formula (2-22) poot :,.:- -'-1" $..5'' Llicitib olic .47 Ho s Formula (2-23) Formula (2-24) Formula (2-25)

6 Date Regue/Date Received 2022-12-09 =7)),3110 =
lose :==0)cHo -Formula (2-26) Formula (2-27) Formula (2-28) yir en) OH .011 CHO
.1 101) HO' " oil CHO CHO Old Formula (2-29) Formula (2-30) Formula (2-31) %Ty] 00.

GOO
Formula (2-32) Formula (2-33) Formula (2-34) y -Formula (2-35).
Further, the carbon quantum dot is selected from one of the following structural formulas:

7 Date Recue/Date Received 2022-12-09 n3 * 0 cm 0% *
_ HO
.,_ J , 101 ---a n1 Nee _ li HD
n2 Formula (2-36) I
.0-7-JOC¨ ¨OH
C-1,,,õ
il 1 rt2 n t 1 Formula (2-37)

8 Date Recue/Date Received 2022-12-09 1-10,,Nr 10 k n2 E, Formula (2-38) nt2 n 1 Formula (2-39) So 0¨CH3 110 40'-0 IN, 5 n I rt2 Formula (2-40)

9 Date Recue/Date Received 2022-12-09 F II
a .'= `--,_ _.:`::? . .- = N,,,.... ,i0 , __ ,._. = '0' 0;C

=""1.H
Formula (2-41).
It should be noted that the above n1, n2, and n3 represent the number of the groups represented in respective directions, and L and T groups may be linked while extending outwards.
The present disclosure further provides a thin film, containing any one of the carbon quantum dots described above. The thin film of the present disclosure may be used for both photoluminescence, for example, used as a backlight panel material, and electroluminescence, for example, used as a light-emitting layer material for an electroluminescence device.
The present disclosure further provides an electronic device, including the above thin film. The 1.0 electronic device includes but not limited to an electroluminescent device, a mobile phone, a computer, a smart wearable device, an in-vehicle display, an Augmented Reality (AR) display, a Virtual Reality (VR) display, a flexible display screen, and a transparent display.
The present disclosure further provides a synthesis method for a carbon quantum dot, including a step of: heating mixed solution containing dye, alkali and polymer polyol, to form the carbon quantum dot. Herein the dye is used to provide the L group, and the polymer polyol may not only be used as a ligand, but also used as the crosslinking group in some cases.
Further, herein the heating mode includes at least one of solvothermal synthesis, microwave-assisted synthesis, and heat injection synthesis.
Preferably, the dye includes at least one of Rhodamine B, Rhodamine 6G, Rhodamine 123, and tetramethylrhodamine B.
Preferably, the alkali includes at least one of a sodium hydroxide, a potassium hydroxide, a sodium carbonate, a sodium bicarbonate, a sodium acetate, a sodium oxalate, a potassium acetate, 1.0 Date Recue/Date Received 2022-12-09 a potassium oxalate, and ammonia water.
Preferably, the polymer polyol includes at least one of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 1000, polyethylene glycol 1500, polyethylene glycol 2000, and polyvinyl alcohol (molecular weight: 2.5-150,000).
Beneficial effects:
(1) In the present invention, a new-type carbon quantum dot material is proposed, the carbon quantum dot contains a series of the structures in Formula (2) as the general formula, this new-type carbon quantum dot material is a fluorescent light-emitting material, has the advantages of high photoluminescence quantum yield (PLQY) (>85%), good stability (such as strong anti-bleaching), and narrow half-peak width (<38nm), and may play a significant role in disease diagnosis, environmental monitoring, tracers, bioimaging, optoelectronic device manufacture and other aspects.
(2) The light-emitting group and the cross-linking group constitute the carbon quantum dot of the present disclosure together. Since a plane or stereoscopic structure is formed between the light-emitting group and the cross-linking group, the carbon quantum dot is stable in overall structure, and wide in applicability.
(3) The carbon quantum dot of the present disclosure may emit light with various colors, and is especially suitable for emitting red light and green light. The thin film and the electronic device prepared by using the carbon quantum dot may emit light with high color saturation.
(4) The synthesis process of the carbon quantum dot of the present invention is simple and feasible, the cost is low, the repeatability is good, and it is favorable for large-scale preparation.
Brief Description of the Drawings Drawings constituting a part of the present disclosure are used to provide further understanding of the present invention, and exemplary embodiments of the present invention and descriptions thereof are used to explain the present invention, and do not constitute improper limitation to the present invention. In the drawings:
Fig. 1 is a photoluminescence spectrum diagram of a carbon quantum dot shown in Formula (2-36) of the present disclosure.
Fig. 2 is a photoluminescence spectrum diagram of a carbon quantum dot shown in Formula (2-37) of the present disclosure.

Date Regue/Date Received 2022-12-09 Fig. 3 is a photoluminescence spectrum diagram of a carbon quantum dot shown in Formula (2-38) of the present disclosure.
Fig. 4 is a photoluminescence spectrum diagram of a carbon quantum dot shown in Formula (2-39) of the present disclosure.
Fig. 5 is a photoluminescence spectrum diagram of a carbon quantum dot shown in Formula (2-40) of the present disclosure.
Fig. 6 is a photoluminescence spectrum diagram of a carbon quantum dot shown in Formula (2-41) of the present disclosure.
Fig. 7 is a transmission electron microscope (TEM) diagram of a carbon quantum dot of Embodiment 2 of the present disclosure.
Fig. 8 is another TEM diagram of the carbon quantum dot of Embodiment 2 of the present disclosure.
Fig. 9 is a TEM diagram of a carbon quantum dot of Embodiment 3 of the present disclosure.
The same reference signs are used for the same parts in the drawings, and the drawings only schematically show implementation schemes of the present disclosure.
Detailed Description of the Embodiments The present invention is further described below in combination with the drawings and specific embodiments, so that those skilled in the art may better understand the present invention and implement it, but the embodiments listed are not intended to limit the present invention. It should be noted that the embodiments described are only a part of the embodiments of the present disclosure, but not all of the embodiments.
In the description, groups such as alkyl, amino, carboxyl, hydroxyl, nitro, sulfonyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, haloalkyl, haloalkoxy, and phosphino that do not specify the number of carbon atoms may select the different numbers of the carbon atoms according to the actual needs.
A "polycarboxylic acid group" refers to a group formed by a compound containing more than two carboxyl groups; a "polyol hydroxyl group" refers to a group formed by an alcohol compound containing more than two hydroxyl groups in a molecule; a "polyphenol hydroxyl group" refers to a group formed by a phenolic compound containing more than two hydroxyl groups in a molecule; a "polyamine group" refers to a group formed by a compound containing more than two amine groups Date Recue/Date Received 2022-12-09 in a molecule; a "polyboronic acid group" refers to a group formed by a compound containing more than two boronic acid groups in a molecule; a "polyaldehyde group" refers to a group formed by a compound containing more than two aldehyde groups in a molecule; a "polybenzonitrile group"
refers to a group formed by a compound containing more than two benzonitrile groups in a molecule;
and a "polyhydrazide group" refers to a group formed by a compound containing more than two hydrazide groups in a molecule. "Unsubstituted" in "substituted or unsubstituted" means that it is not substituted by a substituent, and "substituted" means that the hydrogen atom of the group may be substituted by other groups.
The numbers in polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 1000, polyethylene glycol 1500, and polyethylene glycol 2000 in the present disclosure refer to the molecular weights of the corresponding polyethylene glycols.
In the description of the present disclosure, unless otherwise stated, the meaning of "plurality"
refers to two or more. The basic raw materials polyethylene glycol, Rhodamine, sodium hydroxide, polytetrafluoroethylene and the like used in the present invention may be purchased in major chemical raw material markets at home and abroad.
Embodiment 1: Synthesis of carbon quantum dot containing structure represented by Formula (2-36) Date Regue/Date Received 2022-12-09 + ....15,!sterification "}-1 Activation --4"."-C.
=

O. 0 Allit . , .
IIP
Solvothormal reaction Carbonization , n3 .
all =

. .
../
n 1 IP
" Iiir }n2 Date Recue/Date Received 2022-12-09 30 mg of Rhodamine B, 20 mL of 0.7 M sodium hydroxide aqueous solution, 3 mL
of polyethylene glycol (PEG) 1000 and 1.2 g of phloroglucinol were added to a polytetrafluoroethylene lining, and put into a reaction kettle to perform a hydrothermal reaction, the reaction temperature was 180 C, the reaction time was 12 h, and after the reaction was completed, it was naturally cooled, to obtain crude solution of a reactant, and then the crude solution of the reactant was subjected to centrifugal purification treatment, to obtain 15 mg of the carbon quantum dot containing the structure represented by Formula (2-37), the yield was 50%, the wavelength was 578 nm, the half-peak width was 40 nm, the quantum yield was 72%, and it emitted orange-yellow light. A
fluorescence spectrum diagram was shown in Fig. 1.
Embodiment 2: Synthesis of carbon quantum dot containing structure represented by Formula (2-37) all .
1 ote HO......L OH
.4. HOOC=======LC+1 ............00,, 111) 110 =====
. . . 4g =
Otiozsmoo sctr ...-014

10).........C.=...-141 A
Carbonization a . y .
ill . ---. .
....
==.....4:1H
a Iti Date Regue/Date Received 2022-12-09 30 mg of Rhodamine B, 20 mL of 0.68 M sodium hydroxide aqueous solution, 3 mL
of PEG 200 and 2 g of a citric acid were added to a polytetrafluoroethylene lining, and put into a reaction kettle to perform a hydrothermal reaction, the reaction temperature was 200 C, the reaction time was 10 h, and after the reaction was completed, it was naturally cooled, to obtain crude solution of a reactant, and then the crude solution of the reactant was subjected to centrifugal purification treatment, to obtain 24 mg of the carbon quantum dot containing the structure represented by Formula (2-38), the yield was 80%, the wavelength was 515 nm, the half-peak width was 36 nm, and the quantum yield was 78%. A fluorescence spectrum diagram was shown in Fig. 2.
Embodiment 3: Synthesis of carbon quantum dot containing structure represented by Formula (2-38) so MP/

+
Ho.1=1-014 i mar4 HO ,--NAN 11 11 = 111111110,1 Carbonization , l' Ho 1 "PI

m ..-- . %.41#.104 H¨
1.1 30 mg of Rhodamine B, 20 mL of 0.7 M sodium hydroxide aqueous solution, 3 mL
of PEG 1000 Date Regue/Date Received 2022-12-09 and 3 mL of a glutaric acid were added to a polytetrafluoroethylene lining, and put into a reaction kettle to perform a hydrothermal reaction, the reaction temperature was 190 C, the reaction time was 18 h, and after the reaction was completed, it was naturally cooled, to obtain crude solution of a reactant, and then the crude solution of the reactant was subjected to centrifugal purification treatment, to obtain 12 mg of the carbon quantum dot containing the structure represented by Formula (2-38), the yield was 40%, the wavelength was 575 nm, the half-peak width was 41 nm, and the quantum yield was 74%. A fluorescence spectrum diagram of the carbon quantum dot was shown in Fig. 3.
Embodiment 4: Synthesis of carbon quantum dot containing structure represented by Formula (2-39) OH
+
I

H
Hydrolysis Ilk "if OH 0-) , 0,."141 lir 0 14"' N4/4"==
lir H
Carbonization .....
o r=N o '" " r=-=
H
al a2 411ww Date Recue/Date Received 2022-12-09 15 mg of Rhodamine B, 15 mg of Rhodamine 6G, 20 mL of 0.7 M sodium hydroxide aqueous solution, 3 mL of PEG 800 and 5 mL of a propylene glycol were added to a polytetrafluoroethylene lining, and put into a reaction kettle to perform a hydrothermal reaction, the reaction temperature was 200 C, the reaction time was 10 h, and after the reaction was completed, it was naturally cooled, to obtain crude solution of a reactant, and then the crude solution of the reactant was subjected to centrifugal purification treatment, to obtain 15 mg of the carbon quantum dot containing the structure represented by Formula (2-39), the yield was 50%, the wavelength was 580 nm, the half-peak width was 42 nm, and the quantum yield was 60%. A fluorescence spectrum diagram of the carbon quantum dot was shown in Fig. 4.
Embodiment 5: Synthesis of carbon quantum dot containing structure represented by Formula (2-40) Date Recue/Date Received 2022-12-09 lbw IP"
/.--N 0.
N

*
01, 0 HOO

alp 0 r'14 0 Carbonization C Si * 0).....c**1 ir4( a2 15 mg of Rhodamine B, 15 mg of Rhodamine 123, 2 mg of a sodium hydroxide, 5 mL
of PEG
1000, 20 mL of a dimethyl formamide (DMF) and 3 mL of 1,3-butanediol were added to a polytetrafluoroethylene lining, and put into a reaction kettle to perform a hydrothermal reaction, the Date Recue/Date Received 2022-12-09 reaction temperature was 190 C, the reaction time was 12 h, and after the reaction was completed, it was naturally cooled, to obtain crude solution of a reactant, and then the crude solution of the reactant was subjected to centrifugal purification treatment, to obtain 19 mg of the carbon quantum dot containing the structure represented by Formula (2-40), the yield was 63%, the wavelength was 538 nm, the half-peak width was 67 nm, and the quantum yield was 52%. A
fluorescence spectrum diagram of the carbon quantum dot was shown in Fig. 5.
Embodiment 6: Synthesis of carbon quantum dot containing structure represented by Formula (2-41) +
V
________________________________________________ lir 0 11111 IS , 0 I .
1 Carbonization 41 . ....
is -30 mg of Rhodamine 123, 2 mL of ammonia water, 20 mL of distilled water, 3 mL
of PEG 400 and 15 mg of a phloroglucinol were added to a polytetrafluoroethylene lining, and put into a reaction kettle to perform a hydrothermal reaction, the reaction temperature was 200 C, the reaction time was 18 h, and after the reaction was completed, it was naturally cooled, to obtain crude solution of a reactant, and then the crude solution of the reactant was subjected to centrifugal purification treatment, to obtain 12 mg of the carbon quantum dot containing the structure represented by Formula (2-41), the yield was 40%, the wavelength was 540 nm, the half-peak width was 81 nm, and the quantum yield was 63%. A fluorescence spectrum diagram of the carbon quantum dot was shown in Fig. 6.
Date Recue/Date Received 2022-12-09 The reduction rate of the luminous intensity of the carbon quantum dot of the present disclosure in 2 hours is lower than 1%, while the reduction rate of the luminous intensity of a conventional carbon quantum dot in 2 hours is higher than 10%. It may be seen that the stability of the carbon quantum dot of the present invention is much better than the stability of the conventional carbon quantum dot.
On the basis of a traditional synthesis method for the carbon quantum dot, the present disclosure creatively adds a substance containing the cross-linking group as a raw material, so that the degree of conjugation, one of important parameters in the prepared carbon quantum dot, is greatly enhanced, the stability of the carbon quantum dot is stronger while the degree of conjugation is enhanced, and the particle size of the carbon quantum dot is also increased. For example, as shown in a TEM diagram of a carbon quantum dot in Embodiment 2 of Fig. 7 and Fig. 8, the average particle size of the carbon quantum dot is 8.5 nm. Fig. 9 shows a TEM diagram of a carbon quantum dot in Embodiment 3, the preparation method for the carbon quantum dot of the present disclosure may obtain a carbon quantum dot structure with large particle size, spatial stereostructure, strong stability, high luminous efficiency, and narrow half-peak width.
The traditional synthesis method for the carbon quantum dot generally adopts a solvothermal mode, for example: citric acid and urea are mainly used as carbon sources, distilled water, ethanol and other solvents are used as reaction media, and it is placed in a polytetrafluoroethylene lining for a solvothermal reaction (certain reaction time and reaction temperature).
After the reaction is completed, the carbon quantum dot needs a tedious purification step, including commonly used:
membrane dialysis, multiple centrifugal extraction, gel chromatography purification and the like, and the yield of the obtained carbon quantum dot is low, the composition is complex, the half-peak width of the fluorescence spectrum of the carbon quantum dot is wide, the fluorescence efficiency is low, and it is difficult to achieve large-scale production and disclosure. As a new-type carbon quantum dot, the carbon quantum dot of the present disclosure is simple and feasible in synthesis process, good in repeatability, low in cost, and beneficial to large-scale production, and the obtained carbon quantum dot has excellent luminescence performance, high thermal stability and wide applicability.
It may greatly promote the development and disclosure of the carbon quantum dot in disease diagnosis, environmental monitoring, tracers, bioimaging and optoelectronic device manufacture and other aspects.
The thin film in the embodiments of the present invention may only include the above carbon quantum dot, or may include both the above carbon quantum dot and other substances, such as other carbon quantum dots, an inorganic material, and an organic material. The thin film of the present disclosure may be photoluminescence, or may also be electroluminescence, and the thin Date Regue/Date Received 2022-12-09 film may be prepared by a solution coating mode, or prepared by an evaporation mode according to the actual situations.
The electronic device containing the thin film of the present invention includes but not limited to an electroluminescent device, a mobile phone, a computer, a smart wearable device, an in-vehicle .. display, an AR display, a VR display, a flexible display screens, and a transparent display. The electronic device of the present invention is, for example, the electroluminescent device. The structure of the electroluminescent device may be an upright structure:
substrate/positive electrode/hole injection layer (HIL)/hole transport layer (HTL)/light-emitting layer (EL)/electron transport layer (ETL)/negative electrode; it may also be an inverted structure: substrate/negative electrode/electron transport layer (ETL)/light-emitting layer (EL)/hole transport layer (HTL)/hole injection layer (HIL)/positive electrode; and the material of each layer, except for EL, in the electroluminescent device is selected and used from conventional materials according to the actual needs, and the preparation method may be selected from conventional preparation methods in an existing technology according to the actual needs.
Embodiment 7: Electroluminescent device The carbon quantum dot of the present invention was used as the light-emitting layer material in the electroluminescent device, the structure of the prepared electroluminescent device was:
ITO/ZnO/CDs/mCBP(60 nm)/Mo03(5 nm)/AI, the obtained electroluminescent device was uniform in luminescence, the turn-on voltage of the electroluminescent device was 3 V
without any optimization measures, the light-emitting brightness was 98 cd/m2 under a voltage of 8.8 V, and the external quantum efficiency was greater than 0.1%.
Although the inventor describes and lists the technical schemes of the present disclosure in more detail, it should be understood that it is apparent to those skilled in the art that modifications and/or changes to the above embodiments or equivalent alternative schemes adopted do not depart from the essence of the spirit of the present disclosure, and the terms appearing in the present disclosure are used to describe and understand the technical schemes of the present disclosure, and do not constitute limitations to the present disclosure.

Date Recue/Date Received 2022-12-09

Claims

1. A carbon quantum dot, containing a structure represented by the following Formula (2):
in Formula (2), L is a group represented by the following Formula (1):
in Formula (1), R, R2, R4, R5, R7 and R8 are each independently selected from a group consisting of the following groups: hydrogen, alkyl, amino, carboxyl, hydroxyl, nitryl, sulfonyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, haloalkyl, haloalkoxy, phosphino, and combinations thereof; R3, R6 and R9 are each independently selected from a group consisting of the following groups: substituted or unsubstituted hydroxyl, amino, ethylamino, diethylamino, benzoate, hydroxybenzoate and ethyl benzoate;
T is independently selected from a group consisting of the following groups: a multi-carboxylic acid group, a polyol hydroxyl group, a polyphenol hydroxyl group, a polyamine group, a multi-boronic acid group, a multi-aldehyde group, a multi-benzonitrile group, and a polyhydrazide group; and each of p, m, and n is a positive integer, while p is 2 or more, a plurality of L is the same or different respectively, and while m is 2 or more, a plurality of T is the same or different respectively.

2. The carbon quantum dot according to claim 1, wherein Formula (1) is selected from groups represented by the following structures:

3. The carbon quantum dot according to claim 1, wherein Formula (1) is selected from groups represented by the following structures:
Formula (1-4) Hydrolyzate of Rhodamine B Formula (1-5) Hydrolyzate of Rhodamine B

4. The carbon quantum dot according to claim 1, wherein the T group is independently selected from a group consisting of the following groups: groups represented by an oxalic acid, a malonic acid, a terephthalic acid, a tricarballylic acid, and a citric acid;
groups represented by an ethylene glycol, a propylene glycol, a glycerol, and a hexanetriol; and groups represented by the following structural formulas:

5. The carbon quantum dot according to claim 1, wherein Formula (2) is selected from one of groups represented by the following structures:

6. A thin film, containing the carbon quantum dot according to any one of claims 1-5.

7. An electronic device, comprising the thin film according to claim 6.

8. A synthesis method for the carbon quantum dot according to any one of claims 1-5, comprising a step of: heating mixed solution containing dye, alkali and polymer polyol, to form the carbon quantum dot.

9. The synthesis method for the carbon quantum dot according to claim 8, wherein the heating mode comprises at least one of solvothermal synthesis, microwave-assisted synthesis, and heat injection synthesis;
preferably, the dye comprises at least one of Rhodamine B, Rhodamine 6G, Rhodamine 123, and tetramethylrhodamine B;
preferably, the alkali comprises at least one of a sodium hydroxide, a potassium hydroxide, a sodium carbonate, a sodium bicarbonate, a sodium acetate, a sodium oxalate, a potassium acetate, a potassium oxalate, and ammonia water; and preferably, the polymer polyol comprises at least one of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 1000, polyethylene glycol 1500, polyethylene glycol 2000, and polyvinyl alcohol.