CN103320133A

CN103320133A - Water-phase preparation method of ZnSe:Ag quantum dots

Info

Publication number: CN103320133A
Application number: CN2013102427473A
Authority: CN
Inventors: 李冬梅; 王刚; 唐世弋; 程经纬; 程涛
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2013-06-19
Filing date: 2013-06-19
Publication date: 2013-09-25

Abstract

The invention relates to a water-phase preparation method of ZnSe:Ag quantum dots, belonging to the technical field of composite nano microcrystal materials. The preparation method comprises the following steps: reacting sodium borohydride (NaBH4) and selenium powder to prepare sodium hydrogen selenide (NaHSe), and injecting the sodium hydrogen selenide into a zinc nitrate/3-mercaptopropionic acid solution of which the pH value is regulated by sodium hydroxide so as to react, thereby obtaining a light-brown transparent ZnSe:Ag quantum dot solution. The product obtained by the method provided by the invention has the advantages of uniform dispersion, high stability and less aggregation, and can be used in the fields of biological fluorescence labeling, drug isolation and some photoelectric devices.

Description

The aqueous phase preparation method of ZnSe:Ag quantum dot

Technical field

The present invention relates to a kind of aqueous phase preparation method of ZnSe:Ag quantum dot, belong to composite Nano micro crystal material technical field.

Background technology

ZnSe is a kind of important direct band gap II-VI family semiconductive luminescent materials, be zincblende lattce structure, belong to face-centered cubic crystal, wideer band gap (2.8eV) and bigger bound energy (21meV) are arranged, at room temperature the direct transition luminescence wavelength of energy gap is in the royal purple optical range.Be that the light of 0.5-22 μ m has the good transmission performance to wavelength region, cover visible-infrared band scope substantially, and material toxicity is low, is applicable to photoelectric device, biological detection, fields such as mark and imaging.

Realize the widespread use of ZnSe in photoelectricity and biological field, must obtain the high and luminous stable ZnSe material of quantum yield, the luminous intensity of ZnSe quantum dot own is poor, and quantum yield is low, and doping can improve the luminous intensity of ZnSe quantum dot.Can change raw-material can being with by effective doping, introduce impurity level, and then change the fluorescent characteristic of material, regulate its fluorescence emission spectrum, improve fluorescence efficiency.

The doping to the ZnSe quantum dot at present mainly concentrates on Cu and Mn element, then is blank to the research of the doping of Ag.But the less stable of ZnSe:Cu and ZnSe:Mn is generally preserved i.e. appearance precipitation about 7 days.Patent of the present invention adopts the doping of Ag element, has filled up the blank of relevant ZnSe quantum dot Ag doping both at home and abroad, and has improved the stability of ZnSe doped quantum dot when improving luminous intensity and quantum yield effectively.

The synthetic Ag doped nano-material of water is under the effect of dispersion agent, allows Zn source, Se source and a certain amount of Ag source react under alkaline environment and generates the ZnSe:Ag quantum dot solution.Compare with traditional oil phase preparation technology, aqueous process control simple to operate, easy, temperature of reaction are low, and the sample that obtains is water-soluble, and bio-compatibility is good.

Summary of the invention

The object of the present invention is to provide a kind of method for preparing fluorescence intensity height, luminous stable, ZnSe:Ag quantum dot that toxicity is low.

The present invention is a kind of aqueous phase preparation method of ZnSe quantum dot of Ag doping, and the mode of grow doping is adopted in experiment, and doping Ag is added in the zinc source.It is characterized in that having following preparation process and step:

A. in the 100ml pyriform bottle, behind the about 30min of feeding nitrogen, add 0.8mmolNaBH successively ₄, 0.2mmol selenium powder (Se) and 2ml deionized water; Then the pyriform bottle is reacted 1h under nitrogen protection, treat that the black selenium powder all disappears, generate water white transparency settled solution I, i.e. NaHSe solution; Chemical equation is:

4NaBH ₄?+?2Se?+7H ₂O?——?2NaHSe?+?Na ₂B ₄O ₇?+?14H ₂↑

B. in the 250ml there-necked flask, add 0.8mmol zinc nitrate, 0.024mmol Silver Nitrate, 100ml deionized water and 200 μ L 3-thiohydracrylic acids successively, feed the oxygen in the nitrogen removal solution, regulate pH value to 9 with 1M NaOH then, place 100 ℃ of oil baths to heat 1h three-necked flask, obtain water white transparency settled solution II, i.e. Zn (NO ₃) ₂(Ag) solution;

C. with syringe the solution I is injected into rapidly in the solution II, continues to pass to nitrogen and keep 100 ℃ of oil baths, obtain fallow transparent ZnSe:Ag quantum dot solution behind the reaction 3h; Chemical equation is:

Zn(NO ₃) ₂(Ag)?+?NaHSe?——?ZnSe(Ag)+NaNO _3?+?HNO ₃

The ZnSe:Ag quantum dot of the present invention preparation has good stability, the characteristics such as few of reuniting, and makes it demonstrate very big application prospect in fields such as biological fluorescent labelling and photoelectric materials.

Outstanding feature of the present invention is: (1) prepares the ZnSe:Ag quantum dot first, sends blue-greenish colour light under ultraviolet lamp; (2) adopt aqueous phase synthesis method preparation (100 ℃) under relatively low temperature, experimental implementation is simple, and process is controlled easily, and the quantum dot of preparation need not the secondary conversion, can directly apply to biomarker; (3) quantum dot for preparing can be stored four months under the low-temperature dark storage, its stability was described better.Solved the quantum dot less stable, can't the prolonged storage problem.

Description of drawings

Fig. 1 the present invention makes X-ray diffraction (XRD) figure of sample;

Fig. 2 the present invention makes high power perspective electron microscope (HRTEM) photo of sample;

Fig. 3 the present invention makes energy dispersion (EDS) power spectrum of sample;

The UV, visible light that Fig. 4 the present invention makes sample absorbs (uv-vis) spectrum;

Fig. 5 the present invention makes the PL(photoluminescence of sample ZnSe and ZnSe:Ag) spectrogram.

Fig. 6 the present invention makes the PL(photoluminescence of sample ZnSe:Ag different levels of doping) spectrogram.

Embodiment

A. in the 100ml pyriform bottle, behind the about 30min of feeding nitrogen, add 0.8mmolNaBH successively ₄, 0.2mmol selenium powder (Se) and 2mL deionized water; Then the pyriform bottle is reacted 1h under nitrogen protection, treat that the black selenium powder all disappears, generate water white transparency settled solution I, namely NaHSe solution is stand-by;

B. in the 250ml there-necked flask, add 0.8mmol zinc nitrate, 0.024mmol Silver Nitrate, 100ml deionized water and 200 μ L 3-thiohydracrylic acids successively, feed the oxygen in the nitrogen removal solution, regulate PH to 9 with 1M NaOH then, place 100 ℃ of oil baths to heat 1h three-necked flask, obtain water white transparency settled solution II, i.e. Zn (NO ₃) ₂(Ag) solution;

C. with syringe the solution I is injected into rapidly in the solution II, continues to pass to nitrogen and keep 100 ℃ of oil baths, obtain fallow transparent ZnSe:Ag quantum dot solution behind the reaction 3h.

The present invention utilizes X-ray diffractometer and fluorescence protractor that laboratory sample is carried out structure and fluorescence property analysis, utilize the EDS energy spectrometer that the ZnSe:Ag quantum dot that makes is carried out composition analysis, and observe its ultrastructure by high resolution transmission electron microscope, its test result shows: as shown in Figure 1, the XRD diffractive features peak position of ZnSe and ZnSe:Ag quantum dot is consistent, greatly about 27.2 ^o, 45.2 ^oWith 53.6 ^oThe place conforms to (111), (220) and (311) crystal plane of zincblende lattce structure ZnSe crystal, illustrates that prepared quantum dot is zincblende lattce structure, and the Ag doping does not cause obvious influence to the structure of ZnSe crystal.Locate to be Ag at 22.9 ° with 33.5 ° ₂Se has illustrated Ag ₂Se generates; Fig. 2 is the high power transmission electron microscope photo (blackspot) of ZnSe:Ag quantum dot, and the particle scale of quantum dot is evenly distributed, and does not reunite.Size is about 3nm.Fig. 3 is the EDS energy spectrogram of ZnSe:Ag quantum dot, can find out elements such as containing Ag, Zn, Se in the product, and is consistent with ZnSe:Ag quantum dot chemical ingredients.The characteristic peak of S element is because contain the S ion in the used 3-Thiovanic acid of experiment itself; Because the sample of preparation is to be carried on the copper mesh to observe, so the characteristic peak of Cu element is due to the copper mesh; Ag content is obviously higher, and its major cause is Ag ₂The Se compound produces.Fig. 4 is the ultraviolet-absorption spectrum of ZnSe quantum dot and ZnSe:Ag quantum dot.Compare ZnSe quantum dot ABSORPTION EDGE, ZnSe:Ag quantum dot ABSORPTION EDGE is wideer, in conjunction with the XRD figure picture of ZnSe:Ag quantum dot, the Ag that exists in the preparation sample is described ₂Se causes its ABSORPTION EDGE to broaden.But the beginning turning point is greatly about the 375nm place.Illustrate that the ZnSe:Ag quantum dot does not change with respect to the ZnSe quantum-dot structure, conform to as the gained conclusion with XRD figure.Fig. 5 is ZnSe and the fluorescence emission spectrum of ZnSe:Ag quantum dot under the 325nm excitation wavelength.ZnSe has two peak positions greatly about 375nm and 460nm place as shown in the figure, and the position of the corresponding ABSORPTION EDGE emission peak of 375nm as can be known is the band edge emission of ZnSe quantum dot, and the crest at 460nm place is the defective peak.Behind ZnSe doping Ag ion, a fluorescence emission peak is only arranged, with respect to ZnSe quantum dot generation red shift at the 475nm place.Explanation may be Ag gap doping Ag _iEnter the new impurity level of formation in the ZnSe quantum dot forbidden band, become the current carrier deathnium.Realized Ag ion doping to a certain degree, and because doping rear impurity energy level and surface state are in " competition " state, current carrier trends towards on impurity level compound, cause the band edge emission of 375nm place to disappear, transfer recombination luminescence on the 475nm place impurity level to, and obviously strengthened luminous intensity.Fig. 6 is the quantum dot PL(photoluminescence of different levels of doping) spectrogram.Doping content is that 12.5% quantum dot light emitting intensity is the highest as can be seen.The quantum dot of this concentration sends blue-greenish colour light under the 365nm ultra violet lamp.Be similarly blue-greenish colour and doping content is lower than 12.5% quantum dot light emitting, but luminous intensity reduces with doping content.When doping content is too high, reach at 15% o'clock, emission peak obviously weakens, and this moment is luminous to be unconspicuous colour of loess coloured light.When doping content was low, the quantum dot emission peak was not obvious, and can't form impurity level preferably this moment, cause current carrier compound not obvious on impurity level, thereby luminous intensity is lower.And when doping content reaches 12.5%, fully form impurity level, and current carrier is compound on impurity level, the luminous intensity height, and emission peak is obvious.But when doping content was excessive, Ag ion and Se ionic bond generated a large amount of Ag ₂Se, and the quantum dot agglomeration may occur, thus it is luminous to have influenced in the quantum dot impurity level, causes its luminous intensity to reduce greatly.

Claims

1. the aqueous phase preparation method of a ZnSe:Ag quantum dot is characterized in that having following preparation process and step:

A. in the 100ml pyriform bottle, behind the about 30min of feeding nitrogen, add 0.8mmolNaBH successively ₄, 0.2mmol selenium powder (Se) and 2ml deionized water; Then the pyriform bottle is reacted 1h under argon shield, treat that the black selenium powder all disappears, generate water white transparency settled solution I, namely NaHSe solution is stand-by;

B. in the 250ml there-necked flask, add 0.8mmol zinc nitrate, 0.024mmol Silver Nitrate, 100ml deionized water and 200 μ L 3-Thiovanic acids successively, feed the oxygen in the nitrogen removal solution, regulate PH to 9 with 1M NaOH then, place 100 ℃ of oil baths to heat 1h three-necked flask, obtain water white transparency settled solution II, i.e. Zn (NO ₃) ₂(Ag) solution;