CN105524616A - Aqueous phase preparation method for CdZnTe: Eu quantum dot - Google Patents

Abstract

The invention relates to an aqueous phase preparation method for a CdZnTe: Eu quantum dot. The method comprises the following steps: reacting sodium borohydride (NaBH4) with tellurium powder so as to prepare sodium hydrogen telluride (NaHTe); then injecting sodium hydrogen telluride into a zinc nitrate/cadmium nitrate-mercaptoacetic acid solution with a pH value having been adjusted with sodium hydroxide; and allowing sodium hydrogen telluride to react with the solution to produce a pistachio CdZnTe: Eu quantum dot solution. The prepared CdZnTe: Eu quantum dot solution has the advantages of uniform dispersion, good stability and little agglomeration and can be applied to fields like biological fluorescent labeling, drug separation and certain photoelectric devices.

Description

The aqueous phase preparation method of CdZnTe:Eu quantum dot

Technical field

The present invention relates to a kind of aqueous phase preparation method of CdZnTe:Eu quantum dot.

Background technology

CdZnTe is the group Ⅱ-Ⅵ compound semiconductor material that a kind of photoelectric properties are excellent, there is uptake factor high, the advantages such as energy gap and solar spectrum match, CdZnTe is had a wide range of applications in solar cell preparation, want to realize the widespread use of CdZnTe in photoelectricity and biological field, the CdZnTe material of low toxicity, high quantum production rate and radiance temperature must be obtained.

Rear-earth-doped II-VI group semi-conductor has the photoelectric property of multiple spectra luminescence, excellence such as long labor light life-span, high luminous efficiency, low temperature paramagnetism etc., becomes the focus studied in field of nanometer material technology in recent years.Due to Aqueous phase, to prepare the higher ternary quantum dots of Zn/Cd ratio comparatively difficult, therefore the mode of rare earth doped Eu is wherein considered herein, can while maintenance CdZnTe quantum dot high quantum production rate and good luminescent properties, Eu is to reduce the content of Cd in doping, prepares the hypotoxic CdZnTe quantum dot of higher utility value.

In the aqueous solution of acidic conditions, Cd source, Zn source and tellurium source are under the effect of dispersion agent, and reaction bonded generates CdZnTe quantum dot solution.Compared with under alkaline condition, can prevent the hydrolysis of Zn ion from producing ZnO or ZnOH in acid condition, be conducive to the formation of CdZnTe quantum dot.Be mixed into the ethanolic soln of some ratios in the solution, can Eu be promoted ³⁺dispersed in the solution, facilitate Eu ³⁺mix better in CdZnTe quantum dot.

Summary of the invention

The object of the present invention is to provide a kind of aqueous phase preparation method of CdZnTe:Eu quantum dot.

For achieving the above object, the present invention adopts following technical scheme:

1. an aqueous phase preparation method for CdZnTe:Eu quantum dot, is characterized in that the concrete steps of the method are:

A. under protection of inert gas, by NaBH ₄with tellurium powder by (2 ~ 3): the mol ratio of 1 is dissolved in the mixed solvent of second alcohol and water by the volume ratio of 1:3; Then react in ice-water bath and all disappear to black tellurium powder, generate the transparent settled solution I of lavender, i.e. NaHTe solution, the concentration of this solution is at 0.05mol/L ~ 0.1mol/L;

B. be dissolved in deionized water by cadmium nitrate and zinc nitrate, separately add 3-Thiovanic acid, wherein the mol ratio of Zn:Cd:3-Thiovanic acid is 0.4:0.04:1, then adjust ph to 5.5 ~ 6.5; Be enclosed in 75 DEG C ~ 85 DEG C temperature ranges, keep 0.5h ~ 1h, obtain the transparent settled solution II of pistac, wherein Cd (NO ₃) ₂concentration be 2mmol/L ~ 4mmol/L, Zn (NO ₃) ₂concentration be 0.2mmol/L ~ 0.4mmol/L;

C. Europium Metal powder concentrated nitric acid is dissolved, form the europium nitrate standardized solution that concentration is 0.1mol/L; Step a gained solution I is joined in step b gained solution II, and add europium nitrate standardized solution, under sealing, after 150 DEG C ~ 180 DEG C thermostatically heating 4h ~ 6h, pistac CdZnTe:Eu quantum dot solution III can be obtained, namely obtain CdZnTe:Eu quantum dot; Wherein the volume ratio of solution I, solution II and europium nitrate standardized solution used is: 2:100:(0.01 ~ 0.10).

Outstanding feature of the present invention is: (1) whole experimental system carries out in acid condition, inhibit the hydrolysis of Zn ion in the aqueous solution, prepare the ratio that strongly limit Cd:Zn in CdZnTe quantum dot (2) experiment of high stability, evenly clarification in acid condition, while the content reducing toxic Cd ion, mix a small amount of Eu ³⁺the CdZnTe:Eu quantum dot that the fluorescence intensity (3) that can improve quantum dot prepares can storage-stable one month at normal temperatures, illustrates that it has good stability.Compared with the organic pyrolytic process of traditional metal, aqueous process is simple to operate, temperature of reaction is low, and the product obtained has good bio-compatibility.

Accompanying drawing explanation

X-ray diffraction (XRD) figure of Fig. 1 CdZnTe:Eu quantum dot;

Perspective electron microscope (TEM) photo under the different multiples of Fig. 2 CdZnTe:Eu quantum dot;

Fig. 3 different Eu doping content CdZnTe:Eu quantum dot fluorescence spectrogram;

The fluorescence spectrum figure of CdZnTe:Eu quantum dot is synthesized under the different PH condition of Fig. 4;

Fig. 5, is table 1, CdZnTe:Eu quantum dot precipitation status after placement different time.

Embodiment

Embodiment one:

A. by the ratio mixing for standby use of second alcohol and water according to 1:3.In 100mL pear shape bottle, pass into after argon gas is about 30min, add 0.6mmolNaBH successively ₄, 0.2mmol tellurium powder (Te) and 2mL ethanol and water mixed solvent; Then pear shape bottle is placed in ice bath (0 DEG C), under argon shield, reacts 2h, treat that black tellurium powder all disappears, generate the transparent settled solution I of lavender, namely NaHTe solution, stand-by

B.100mL the mol ratio that cadmium nitrate 0.04mmol, zinc nitrate 0.4mmol(change cadmium nitrate and zinc nitrate is added in beaker successively, ensure that Zn:Cd ratio is 10:1), 100mL deionized water and 100 μ L3-Thiovanic acids, then with NaOH, pH value is adjusted to 6, above solution tinfoil sealing is inserted 80 degree of insulation 1h in process furnace, obtain the transparent settled solution II of pistac, i.e. Cd (NO ₃) ₂with Zn (NO ₃) ₂mixing solutions;

C. Europium Metal powder concentrated nitric acid is dissolved, form europium nitrate 0.1mol/L standardized solution, with syringe, solution I is injected into rapidly in solution II, and adds suitable metering europium nitrate standardized solution.Mixing solutions is added in inner liner of reaction kettle and seals, insert in process furnace and can obtain pistac CdZnTe:Eu quantum dot solution III after 150 degree of reaction 4h, keep reaction conditions that reaction is proceeded, different time can obtain the CdZnTe:Eu quantum dot of different glow color and different luminous intensity.

The present invention utilizes X-ray diffractometer, fluorescent emission protractor carries out structure and fluorescence property analysis to laboratory sample, and observe its ultrastructure by high resolution transmission electron microscope, its test result shows: Fig. 1 is X-ray diffraction (XRD) figure of CdZnTe:Eu quantum dot, the peak position of CdZnTe:Eu quantum dot is respectively 22.5 °, 39.2 ° and 44.8 °, (111) of the corresponding Emission in Cubic crystal of position difference of three diffractive features peak appearance, (220), (311) crystal face, its unit cell parameters is positioned at a cube CdTe(PDF65-1081) and cube ZnTe(PDF65-0149) between.The crystalline structure of the CdZnTe:Eu quantum dot of preparation all belongs to face-centered cubic zincblende lattce structure.Fig. 2 is perspective electron microscope (TEM) photo under the different multiples of CdZnTe:Eu quantum dot, and quantum dot is rounded or oval, is uniformly dispersed, and does not occur agglomeration, and can find out the edge of quantum dot clearly.The size of the quantum dot of torispherical is approximately 5nm.From (b), we can significantly find out that spacing of lattice is approximately 0.37nm, and crystallinity is good.Fig. 3 is that difference chooses temperature of reaction 150 DEG C, pH=6, Eu ³⁺doping content is on the impact of CdZnTe:Eu quantum dot fluorescence spectrum.When Eu doping content is 2% time, adulterate very little for the impact of CdZnTe quantum dot, this may be cause getting a desired effect because the amount of doping does not reach requirement.Relative doping concentration be 5% sample then can detect the peak that significantly adulterates, produce a desired effect.Corresponding after doping content is more than 5%, the sample of preparation produces a large amount of precipitation, and can have influence on the formation of CdZnTe main body when this shows Eu excessive concentration, be unfavorable for the generation of quantum dot, the Eu content in CdZnTe main body is optimum experimental condition about 5%.If Eu ³⁺ion occupies the position of symmetry centre in the lattice of substrate material, then launch fluorescent orange (launching main peak is near 590nm); If Eu ³⁺ion occupies center of asymmetry in the lattice of substrate material, then launch red fluorescence (launching main peak for being greater than 600nm).Eu then in CdZnTe:Eu quantum dot ³⁺ion should belong to the type occupying center of asymmetry.Known, 2% doping and 5% doping are Eu ³⁺occupy center of asymmetry type luminous.Fig. 4 is the fluorescence spectrum figure synthesizing CdZnTe:Eu quantum dot under different PH condition.As can be seen from the figure, when pH value is 6, fluorescent effect is the strongest.This may be due to Te in CdZnTe:Eu quantum dot forming process ^2-and OH ^-there is competitive relation, when there is a large amount of OH in solution ^-during ion, generate Zn (OH) ₂, Eu (OH) ₂precipitation hinders generation and the Eu of CdZnTe quantum dot ³⁺mixing of ion.Fig. 5 is that under different condition, CdZnTe:Eu quantum dot places the Ultraluminescence figure after 7 days.Select that Zn/Cd mol ratio is 10, reaction times 16h, pH value are 6, temperature of reaction 150 DEG C and 180 DEG C prepare CdZnTe:Eu quantum dot respectively under Eu doping content 2% and 5% condition.And place respectively have recorded its precipitation status in 7 days, 15 days, 30 days to preparing sample.

Compared with low temperature (150 DEG C) sample, the quantum dot that higher temperature (180 DEG C) conditioned response obtains just produced precipitation at about 7 days.And the sample of relative doping concentration higher (5%) the sample pellet speed obtained relative to lower concentration (2%) is also than comparatively fast.

In addition, along with the prolongation of storage period, the halfwidth of quantum dot broadens, this is due to the prolongation along with storage period, short grained quantum dot is adsorbed on macrobead quantum dot surface, result in the uneven of quantum dot size distribution, thus the halfwidth of fluorescence emission spectrum is broadened.The increase of Zn/Cd mol ratio can cause the reduction of quantum yield, and this is because adding of Zn increases assertive evidence defect relevant with Zn in CdTe dot matrix.

Claims (1)

1. an aqueous phase preparation method for CdZnTe:Eu quantum dot, is characterized in that the concrete steps of the method are:

A. under protection of inert gas, by NaBH ₄with tellurium powder by (2 ~ 3): the mol ratio of 1 is dissolved in the mixed solvent of second alcohol and water by the volume ratio of 1:3; Then react in ice-water bath and all disappear to black tellurium powder, generate the transparent settled solution I of lavender, i.e. NaHTe solution, the concentration of this solution is at 0.05mol/L ~ 0.1mol/L;

B. be dissolved in deionized water by cadmium nitrate and zinc nitrate, separately add 3-Thiovanic acid, wherein the mol ratio of Zn:Cd:3-Thiovanic acid is 0.4:0.04:1, then adjust ph to 5.5 ~ 6.5; Be enclosed in 75 DEG C ~ 85 DEG C temperature ranges, keep 0.5h ~ 1h, obtain the transparent settled solution II of pistac, wherein Cd (NO ₃) ₂concentration be 2mmol/L ~ 4mmol/L, Zn (NO ₃) ₂concentration be 0.2mmol/L ~ 0.4mmol/L;

C. Europium Metal powder concentrated nitric acid is dissolved, form the europium nitrate standardized solution that concentration is 0.1mol/L; Step a gained solution I is joined in step b gained solution II, and add europium nitrate standardized solution, under sealing, after 150 DEG C ~ 180 DEG C thermostatically heating 4h ~ 6h, pistac CdZnTe:Eu quantum dot solution III can be obtained, namely obtain CdZnTe:Eu quantum dot; Wherein the volume ratio of solution I, solution II and europium nitrate standardized solution used is: 2:100:(0.01 ~ 0.10).