JP2017160073A - Method for producing CdSe colloidal particles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce CdSe colloidal particles which have a particle diameter in a range of 2 to 5 nm, a half-width of 30 nm or less at a peak in a PL spectrum, high quantum efficiency, and high quality, at high yield.SOLUTION: A Se raw material liquid is prepared by mixing a Se source, a compound having a functional group of -COOH or -P=O, and a non-coordinating solvent, then maintaining the mixture at a temperature of 200 to 260°C for at least 3 hours, and subsequently decreasing the temperature of the mixture to 90 to 110°C. The above-described Se raw material liquid is poured into a Cd raw material liquid of 270 to 290°C, and the liquids are mixed and then maintained for 10 minutes to 2 hours to prepare a synthetic liquid. A polar solvent is added to the resultant liquid, and the polar solvent and the resultant liquid are mixed with each other to generate colloid aggregated particles, a nonpolar solvent is added to CdSe colloid aggregated particles obtained by subjecting the resultant liquid to solid-liquid separation, and the nonpolar solvent and the CdSe colloid aggregated particles are mixed with each other to make a liquid in which CdSe colloidal particles are dispersed. A polar solvent is added to the resultant liquid, the polar solvent and the resultant liquid are mixed with each other to make aggregated particles, a nonpolar solvent is then added to the aggregated particles, and the nonpolar solvent and the aggregated particles are mixed with each other to obtain CdSe colloidal particles.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing CdSe colloidal particles, which are a kind of visible light emitting colloidal particles of a photoluminescent material.

  Since the concept of quantum size effect was introduced in the early 1980s, CdSe (cadmium selenide) colloidal particles are the most studied nanocrystals among inorganic semiconductor nanoparticles. In order to produce high-quality CdSe colloidal particles, a very successful production method has been established (for example, see Non-Patent Document 1). The method shown in Non-Patent Document 1 uses trioctylphosphine (TOP) or tributylphosphine (TBP) as the alkylphosphine in order to make a precursor between Se (selenium) and alkylphosphine.

  However, TOP and TBP are harmful and chemically unstable substances, and are expensive materials, which have been a heavy burden for commercialization. In order to improve this point, CdSe colloidal particles using octadecylamine (ODA) and octadecene (ODE), which are low environmental impact and inexpensive solvents, while maintaining the quality of the colloid shown in Non-Patent Document 1. Is disclosed (for example, see Non-Patent Document 2).

C. B. Murray et al. J. Am. Chem. Soc. 1993, 115, 8706-8715 H. Shen et al. CrystEngComm, 2009, 11, 1733-1738

In general, in the colloidal phosphor that is a visible light-emitting colloidal particle, it is important to precisely control the emission wavelength, and according to the principle of the quantum size effect, it can precisely control the particle size of the CdSe colloidal particle. It is in. In the method of Non-Patent Document 2, the particle size of CdSe colloidal particles is controlled by changing the reaction time using a Se raw material liquid in which a predetermined Se-ODA complex is formed. However, in this method, since the factor for controlling the particle size is limited to the reaction time, in order to obtain a CdSe colloidal particle having a minute particle size of less than 2 nm, it is necessary to shorten the reaction time to less than 1 minute. Was extremely difficult. In addition, in order to obtain CdSe colloidal particles having a particle diameter exceeding 8 nm, the reaction time required a long time exceeding 2 hours, and there was a problem that the production efficiency was lowered. In addition, since the binding affinity between Se and an amino group (—NH ₂ ) is weak compared to other functional groups (—COOH, —P═O), the Cd—Se monomer is easily thermally dissociated, and nucleation and There was a problem that the separation of growth was relatively difficult and the particle size distribution was wide. On the other hand, in the above method, a waste liquid containing a large amount of nitrogen is discharged. Regulations on the concentration of nitrogen in the waste liquid that can be discharged into the sea are strictly stipulated by laws and regulations related to marine environmental conservation, and it is expected that the waste liquid will contain a large amount of nitrogen, so this is a major obstacle in mass production. Become.

  An object of the present invention is to provide high-quality CdSe with high quantum efficiency, in which the particle size is in the range of 2 to 5 nm and the half width at the peak of the photoluminescence spectrum (hereinafter referred to as “PL spectrum”) is 30 nm or less. It is to provide a method for producing colloidal particles with high yield.

  The present inventors paid attention to the organic ligand X of the Se-X complex formed in the Se raw material liquid, and the organic ligand having a functional group other than the phosphorus (P) group is a capping agent during the reaction. I found out that it works as well. By adjusting the binding affinity between the functional group of the organic ligand X as the capping agent and Cd-Se, the adsorption / desorption rate of the organic ligand X to the CdSe colloidal particles is adjusted, and the organic ligand Focusing on the fact that the difficulty of growth of CdSe monomer can be adjusted by selecting the bulkiness of the structure of X, the present invention has been achieved.

  According to a first aspect of the present invention, in a method for producing CdSe colloidal particles by injecting and mixing an Se raw material liquid into a Cd raw material liquid, (a) the Se raw material liquid is mixed with an Se source and —COOH or —P Prepared by mixing a compound having a functional group of ═O and a non-coordinating solvent, heating to a temperature of 200 to 260 ° C., holding for at least 3 hours, and subsequently lowering to a temperature of 90 to 110 ° C. And (b) injecting and mixing the Se raw material liquid maintained at a temperature of 90 to 110 ° C. into the Cd raw material liquid maintained at a temperature of 270 to 290 ° C., and then 10 minutes from the injection start time. Hold for ~ 2 hours to prepare a synthesis solution and grow CdSe colloid nuclei generated in the synthesis solution; and (c) add a polar solvent to the solution in which the CdSe colloid nuclei have grown and mix. Dispersed in the liquid CdSe colloidal particles to be CdSe colloidal agglomerated particles, (d) a step of solid-liquid separation of the liquid to recover the CdSe colloidal agglomerated particles, and (e) a nonpolar solvent for the recovered CdSe colloidal agglomerated particles. And (c) adding a polar solvent to the liquid and mixing the CdSe colloidal particles dispersed in the liquid into CdSe colloidal agglomerated particles. (G) recovering the CdSe colloidal aggregated particles by solid-liquid separation of the liquid; and (h) adding a nonpolar solvent to the recovered CdSe colloidal aggregated particles to mix and disperse the CdSe colloidal particles. A method for producing CdSe colloidal particles, comprising the steps of (a) to (h) in the order of steps.

  The second aspect of the present invention is the invention based on the invention of the first aspect, and is repeated once or twice or more after the step (h) from the step (f) to the step (h). This is a method for producing CdSe colloidal particles.

  In the method for producing CdSe colloidal particles according to the first aspect of the present invention, a Se source, a compound having a functional group of —COOH or —P═O which is an organic ligand having an electron donating property, a non-coordinating solvent, After mixing, the Se raw material liquid is mixed with the Cd raw material liquid at an energetically stable stage where the complex form of the Se source and the compound having an electron-donating organic ligand has reached an equilibrium state. The organic ligand functions as a capping agent, and this organic ligand repeatedly adsorbs and desorbs on the surface of the CdSe colloid to control the growth of CdSe nuclei. The above functional group preferably functions as a capping agent, and without using an organic solvent containing nitrogen, a fine particle size is maintained during the growth process to particles, and the particle size is 2 to 5 nm. A high-quality CdSe colloidal particle having a high quantum efficiency and having a half-width of 30 nm or less at the peak is obtained. In this CdSe nucleus growth process, Cd and Se in the raw material liquid are consumed, and the yield can be increased.

  In the method for producing CdSe colloidal particles according to the second aspect of the present invention, the step of converting the CdSe colloidal particles into CdSe colloidal agglomerated particles by adding a polar solvent and the addition of the nonpolar solvent to reconstitute the CdSe colloidal agglomerated particles into CdSe colloidal particles. By repeating the dispersing step, the CdSe colloidal particles are washed, and the half width is further narrowed.

It is a flowchart which shows the manufacturing process of the CdSe colloidal particle of embodiment of this invention.

  Next, an embodiment for carrying out the present invention will be described with reference to the drawings.

  The CdSe colloidal particles of this embodiment are made through the steps shown in FIG. The temperature shown in FIG. 1 is the temperature of the embodiment of the present invention. Each raw material is weighed under an inert gas atmosphere such as nitrogen gas in order to avoid reaction with the atmospheric gas of each raw material.

[Preparation of Cd raw material solution]
In the Cd raw material liquid of the first embodiment, a cadmium oxide such as powdered metal cadmium (Cd) or powdered cadmium oxide (CdO) as a Cd source is placed in a container substituted with an inert gas, This is prepared by adding a carboxylic acid and a non-coordinating solvent and mixing them, followed by heating. Examples of the carboxylic acid include saturated fatty acids such as formic acid, acetic acid, and propionic acid, and unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid. Non-coordinating solvents include octadecene (ODE: C ₁₈ H ₃₆ ), trioctyl phosphine (TOP: C ₂₄ H ₅₁ P), trioctyl phosphine oxide (TOPO: C ₂₄ H ₅₁ OP), oleylamine (OLA: C ₁₈ H ₃₇ N), hexadecylamine (HDA: C ₁₆ H ₃₅ N), and the like. 2-6 mol of carboxylic acid and 50-300 mol of non-coordinating solvent are added to 1 mol of Cd source. This container is heated with an oil bath or the like while passing an inert gas through the container containing the mixture of raw materials. The temperature reached by heating the mixture of each raw material in this oil bath is 270 to 290 ° C. At this temperature, the liquid mixture becomes transparent, and a 270 to 290 ° C. Cd raw material liquid is prepared. When the temperature of the Cd raw material liquid is less than the lower limit value, the reaction with the Se raw material liquid described later hardly proceeds, and when the temperature exceeds the upper limit value, the Cd raw material liquid easily evaporates.

[Preparation of Se raw material liquid]
In the Se raw material liquid of the present embodiment, selenium oxide such as powdered metal selenium (Se) or powdered selenium oxide as a Se source is placed in a container substituted with an inert gas, and electron donating property is added thereto. A compound having an organic ligand and a non-coordinating solvent are mixed and heated. In selecting a compound having an organic ligand having an electron donating property, it is considered that the coating rate of the functional group of the capping agent and its density are important factors in controlling the particle size. Specifically, when the coating speed of the capping agent is small, the growth of CdSe colloidal particles is fast, and when the coating speed is high, the growth of CdSe colloidal particles is slow. Further, when the bulk of the capping agent is small, the growth of CdSe colloidal particles is slow, and when the bulk is large, the growth of CdSe colloidal particles is fast. From the above viewpoint, the compound having an electron-donating organic ligand of the present embodiment includes a compound having a functional group of —COOH or —P═O and having no functional group containing nitrogen. It is done. Examples of the compound having a functional group of —COOH include oleic acid, linoleic acid, or arachidic acid having a small bulkiness; phthalic acid, isophthalic acid, terephthalic acid having a large bulkiness, and the like. Moreover, as a compound which has a functional group of -P = O, a bulky dioctyl phosphine oxide or a tri-n-octyl phosphine oxide is mentioned.

The first characteristic point of the present embodiment is that, after the Se source and the compound having an electron-donating organic ligand reach the complex form in a predetermined equilibrium state while changing the complex form, It is to prepare a stable Se raw material liquid. Non-coordinating solvents include octadecene (ODE: C ₁₈ H ₃₆ ), trioctyl phosphine oxide (TOPO: C ₂₄ H ₅₁ OP), oleylamine (OLA: C ₁₈ H ₃₇ N), hexadecylamine (HDA: C ₁₆ H ₃₅ N) and the like. 1 to 10 mol of a compound having an electron-donating organic ligand and 2 to 100 mol of a non-coordinating solvent are added to 1 mol of Se source. Similar to the preparation of the Cd raw material liquid, the container is heated with an oil bath or the like while passing an inert gas through the container containing the mixed liquid of the respective raw materials. The temperature at which each liquid mixture of raw materials is heated in this oil bath is 200 to 260 ° C., and the holding time at the heated temperature is at least 3 hours. When the heating temperature is less than 200 ° C., the Se source is not sufficiently dissolved in the organic solvent, and an undissolved portion of the Se source is easily generated. Moreover, when heating temperature exceeds 260 degreeC, there exists a malfunction that volatilization of organic substance becomes dominant and it has a bad influence on formation of Se organic complex. If the retention time is less than 3 hours, the Se organic complex will not be in a complex form in an equilibrium state. After heating, the container is taken out from the oil bath and cooled by air cooling to bring the final Se raw material liquid to a temperature of 90 to 110 ° C. When the temperature of the Se raw material liquid falls below the lower limit, problems such as the generation of an organic salt of Se occur. The Se source is preferable because metal selenium is easily dissolved.

[Synthesis of Cd raw material liquid and Se raw material liquid]
The synthesis of the Cd raw material liquid and the Se raw material liquid is performed by a hot soap method. That is, in a state where an inert gas is passed through a container containing Cd raw material liquid and this container is heated in an oil bath, Se raw material liquid at 90 to 110 ° C. is used in a Cd raw material liquid at 270 to 290 ° C. using a syringe. Then, the Cd raw material liquid and the Se raw material liquid are synthesized. Specifically, it is injected at a pushing speed of 1 to 10 mL / second into a syringe having an inner diameter of 10 mm. When it is slowly injected at a rate lower than the lower limit, nuclei are formed again on the surface of the nuclei formed in the liquid, the nuclei are less likely to be minute, and the half-value width at the peak of the PL spectrum is widened. The injection operation is difficult at high speeds exceeding the upper limit. Thereby, a synthetic liquid is prepared by mixing the Se raw material liquid with the Cd raw material liquid. As a method of mixing the Se raw material liquid with the Cd raw material liquid, a mixing method such as nozzle mixing or ejector mixing may be employed using an inert compressed gas depending on the scale of mixing. The prepared synthesis solution is held at a temperature of 245 to 255 ° C. to grow CdSe colloid nuclei. When an energetically stable Se raw material solution containing a compound having an electron-donating organic ligand and reaching a complex state in a predetermined equilibrium state is injected, the organic ligand of the above compound becomes a capping agent. This organic ligand repeatedly adsorbs and desorbs on the surface of the CdSe colloid to control the growth of CdSe nuclei. Specifically, the CdSe monomer grows in the gap where the organic ligand (capping agent) of the above compound is eliminated on the surface of the CdSe colloid. As this growth proceeds, the coverage of the capping agent on the surface of the colloidal particles is improved and this growth becomes difficult to proceed, and as a result, the growth of CdSe nuclei is controlled.

  The characteristic second point of the present embodiment is that the synthesis time calculated from the injection start time is in the range of 10 minutes to 2 hours. Preferably, the synthesis time is in the range of 15 minutes to 1 hour. If the lower limit is less than 10 minutes, the synthesis of the Cd raw material liquid and the Se raw material liquid is insufficient and the yield cannot be increased. If the upper limit of 2 hours is exceeded, the production efficiency tends to deteriorate.

[Preparation of CdSe colloidal particle dispersion]
After the synthesis time has elapsed, the container is taken out from the oil bath, and a polar solvent is added thereto to lower the temperature of the synthesis solution to obtain aggregated particles of CdSe colloids that have grown. Examples of the polar solvent include butanol (C ₄ H ₁₀ O), methanol (CH ₄ O), ethanol (C ₂ H ₆ O), 1 (or 2) -propanol (C ₃ H ₈ O), and the like. After the CdSe colloid aggregated particles are sufficiently agitated with a mixer or the like, the liquid is separated into solid and liquid by centrifugation or the like, and the CdSe colloid aggregated particles as a solid content are recovered. A nonpolar solvent is added to the collected CdSe colloidal aggregated particles, and the mixture is sufficiently stirred with a mixer or the like to disperse the colloidal aggregated particles to obtain a dispersion of colloidal particles. Examples of the nonpolar solvent include hexane (C ₆ H ₁₄ ), toluene (C ₇ H ₈ ), diethyl ether (C ₄ H ₁₀ O), chloroform (CHCl ₃ ), and the like.

  Next, a polar solvent is added to the dispersion liquid of the colloid particles, and the colloid particles are agglomerated by sufficiently stirring with a mixer or the like. For example, CdSe colloid aggregated particles are collected by centrifuging the liquid at 6000 rpm for 5 minutes. A predetermined amount of a nonpolar solvent is added to the recovered CdSe colloidal aggregated particles, and the mixture is sufficiently stirred to loosen the colloidal aggregated particles to form a dispersion of colloidal particles. As a result, a high-quality CdSe colloid having a particle size in the range of 2 to 5 nm, a half width at the PL spectrum peak of 30 nm or less, a quantum efficiency of 55% or more, and a yield of 0.20 or more. Particles can be obtained. The operations of aggregating colloidal particles with a polar solvent, collecting the colloidal agglomerated particles by centrifugation, and dispersing the colloidal particles with a nonpolar solvent are preferably performed once or twice or more.

  Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
A CdSe colloid, which is an II-VI semiconductor, was prepared by a hot soap method in the order of steps shown in FIG.

All weighing operations were performed in a glove box (N ₂ gas atmosphere). Into a 50 mL flask was placed 0.0154 g (0.12 mmol) of cadmium oxide (CdO), 0.1167 mL (0.36 mmol) of oleic acid (OA: C ₁₈ H ₃₄ O ₂ ) and octadecene (ODE: C ₁₈ H). ₃₆ ) After adding and mixing 4.91 mL (13.83 mmol), the flask was removed from the glove box. The flask was immersed in 240 ° C. silicone oil, and the temperature of the mixture was increased while stirring. After the temperature of the mixed solution reached 240 ° C., the temperature was maintained at this temperature for 10 minutes, and then the temperature was raised to 280 ° C. After reaching 280 ° C., the liquid in the flask became a completely transparent liquid. This was used as a Cd raw material liquid. In FIG. 1, it is shown as “Cd-OA solution”.

Into a 50 mL flask was placed 0.188 g (2.38 mmol) of metal selenium (Se), and compound X (6.98 mmol) having an electron-donating organic ligand and octadecene (ODE: C ₁₈ H ₃₆ ). After adding 18.00 mL (50.62 mmol) and mixing, the flask was taken out of the glove box. The flask was immersed in 100 ° C. silicone oil, and the temperature of the mixture was increased while stirring. In this example, X was 2.67 g (6.98 mmol) of trioctylphosphine oxide (TOPO: C ₂₄ H ₅₁ OP). After the temperature of the mixed solution reached 100 ° C., the mixture was held at this temperature for 20 minutes, and then heated to 220 ° C. The liquid in which selenium was dissolved in TOPO was held for 5 hours in a state where the temperature reached 220 ° C., and then the flask was taken out from the silicone oil and air cooling was started. The final liquid cooled to 100 ° C. was used as the Se raw material liquid. In FIG. 1, it is shown as “Se-X solution”.

2 mL of Se raw material liquid (Se-X solution) air-cooled to 100 ° C. is collected with a syringe having an inner diameter of 10 mm, and this is poured into the Cd raw material liquid at a pushing speed of 2 mL / second at a stroke to be mixed. A synthesis solution was prepared by mixing the Se raw material solution. This injection timing was set as the injection start time. Immediately after injection, the liquid temperature began to drop, and CdSe colloid nuclei began to form. After reaching 250 ° C., the temperature was maintained at 250 ° C. to grow CdSe colloidal nuclei. The mixture was held for 10 minutes from the injection start time to synthesize the Se raw material liquid into the Cd raw material liquid, and then the flask was taken out from the silicone oil, where 14.0 mL butanol (C ₄ H ₁₀ O) and methanol (CH ₄ O) 14 By adding 0.0 mL and cooling, a reaction solution in which the CdSe colloidal particles grown were aggregated was prepared. After the cooled reaction liquid was sufficiently stirred with a mixer, the liquid was centrifuged at 6000 rpm for 5 minutes to collect CdSe colloidal aggregated particles.

To the collected CdSe colloid aggregated particles, 2.0 mL of hexane (C ₆ H ₁₄ ) was added, and the mixture was sufficiently stirred to loosen the colloid aggregated particles to obtain a dispersion of colloidal particles. Thereto was added 4.0 mL of butanol (C ₄ H ₁₀ O) and 4.0 mL of methanol (CH ₄ O), and the mixture was sufficiently stirred to make the colloidal particles agglomerated again. Centrifugation for 5 minutes was performed to collect CdSe colloid aggregated particles. To the collected CdSe colloid aggregated particles, 2.0 mL of hexane (C ₆ H ₁₄ ) was added, and the mixture was sufficiently stirred to loosen the colloid aggregated particles to obtain a dispersion of colloidal particles. Thereafter, the above aggregation, recovery and dispersion operations were repeated once more.

<Examples 2-6, Comparative Examples 1-12>
In Examples 2 to 6 and Comparative Examples 1 to 12, an Se raw material solution (Se-X solution) in which selenium was dissolved in Compound X having an electron-donating organic ligand shown in Table 1 was as follows. Prepared. That is, the holding temperature after preparation was set to 220 ° C. and the holding time was set to 5 hours, respectively, and then air-cooled in the same manner as in Example 1 to lower the temperature to 100 ° C., which is a constant temperature, to obtain the final Se. A raw material liquid (Se-X solution) was obtained. In the same manner as in Example 1, these Se raw material liquids were poured into Cd raw material liquids and mixed to prepare a synthetic liquid. At this time, as shown in Table 1, the synthesis time calculated from the injection start time was set between 1 minute and 2 hours. Thereafter, a CdSe colloidal particle dispersion was obtained in the same manner as in Example 1.

<Comparison evaluation>
For the CdSe colloidal particles in the dispersions obtained in Examples 1 to 6 and Comparative Examples 1 to 12, the particle diameter, the half width at the peak of the PL spectrum, the quantum efficiency, and the yield were examined by the methods described below. These results are shown in Table 1 below together with the production conditions.

(1) Particle size of CdSe colloidal particles The CdSe colloidal particles in the dispersion were agglomerated using a polar solvent and collected by centrifugation, and then redispersed in 1.5 mL of tetrachloroethylene (C ₂ Cl ₄ ), and near ultraviolet and visible. Absorbance was measured with an infrared spectrophotometer (manufactured by Hitachi High-Tech Science). The particle size of the colloidal particles was calculated from the peak wavelength.

(2) Half width at the peak of PL spectrum of CdSe colloidal particles The half width at the peak of PL spectrum at the spectrophotometric peak normalized by the peak value of wavelength when calculating the particle size is used as an index of colloidal particle uniformity. Asked. A small half width indicates that the particle size is uniform.

(3) Quantum efficiency of CdSe colloidal particles Quantum efficiency was measured with a quantum efficiency measurement system (manufactured by Otsuka Electronics Co., Ltd.) using the dispersion liquid used for the above-mentioned absorption photometry. The higher the quantum efficiency, the better the crystal quality of the colloidal particles.

(4) Yield of CdSe colloidal particles Calculate the mass of cadmium consumed from the mass of the dried product obtained by aggregating the CdSe colloidal particles in the dispersion using a polar solvent and collecting them by centrifugation. The consumption ratio when the charged cadmium mass was 1 was defined as the yield. A higher yield indicates that the Cd source was consumed without waste.

  As is clear from Table 1, in Comparative Examples 1 to 3, the synthesis time of the Cd raw material liquid and the Se raw material liquid is short in one minute, and thus the synthesis of the Cd raw material liquid and the Se raw material liquid is insufficient and obtained. The CdSe colloidal particles had a very low yield of 0.08 to 0.12.

In Comparative Examples 4 to 9, an Se ligand species having a functional group of —NH ₂ is selected as the electron-donating organic ligand, and the synthesis time of the Cd raw material liquid and the Se raw material liquid is 8 minutes to Although the quantum efficiency was increased to 55-58% because it took enough for 2 hours, the binding affinity between Se and the amino group (—NH ₂ ) was different from other functional groups (—COOH, —P═O). Therefore, the Cd-Se monomer is easily thermally dissociated, the separation of nucleation and growth is relatively difficult, and the particle size distribution is as wide as 31 to 32 nm.

  Further, in Comparative Examples 10 to 12, although the Se ligand species having a functional group of —COOH or —P═O was selected as the electron-donating organic ligand, synthesis of the Cd raw material liquid and the Se raw material liquid was performed. The time was short in 1 minute, and thus the synthesis of the Cd raw material liquid and the Se raw material liquid was insufficient, and the yield of the obtained CdSe colloidal particles was as extremely low as 0.07 to 0.08. In addition, since the Cd-Se monomer was deposited on the surface of the colloidal particles, causing rearrangement and not enough time to improve the quality of the crystals, the quantum efficiency remained at 31 to 33%, and at the peak of the PL spectrum The full width at half maximum was 34 to 36 nm.

  On the other hand, in Examples 1-6, after selecting the Se ligand type | mold which has a functional group of -COOH or -P = O as an organic ligand with an electron-donating property, Se-X liquid Since the holding time after preparing the CdSe liquid was set to 5 hours and the synthesis time of the Cd raw material liquid and the Se raw material liquid was 10 minutes to 2 hours, the CdSe colloidal particles had a particle size of 2.6 to 4.4 nm, and PL The half width at the peak of the spectrum was 30 nm or less, the quantum efficiency was 55% or more, and the yield was as high as 0.20 to 0.25.

  The CdSe colloidal particles produced by the method of the present invention can be used in the fields of displays, illumination, medical images, biosensors, LEDs, and lasers.

Claims (2)

In the method of producing CdSe colloidal particles by injecting and mixing the Se raw material liquid into the Cd raw material liquid,
(a) The Se raw material liquid is mixed with a Se source, a compound having a functional group of —COOH or —P═O and a non-coordinating solvent, and then heated to a temperature of 200 to 260 ° C. for at least 3 hours. Holding and subsequently preparing by lowering the temperature to 90-110 ° C .;
(b) After injecting and mixing the Se raw material liquid maintained at a temperature of 90 to 110 ° C. to the Cd raw material liquid maintained at a temperature of 270 to 290 ° C., the mixture is maintained for 10 minutes to 2 hours from the injection start time. A step of preparing a synthesis solution and growing grains of CdSe colloid nuclei generated in the synthesis solution;
(c) adding a polar solvent to the liquid in which the CdSe colloid nuclei are grown and mixing the mixture to make CdSe colloidal particles dispersed in the liquid into CdSe colloidal aggregated particles;
(d) recovering the CdSe colloidal agglomerated particles by solid-liquid separation of the liquid;
(e) adding a non-polar solvent to the collected CdSe colloidal aggregated particles and mixing them to obtain a liquid in which CdSe colloidal particles are dispersed;
(f) adding a polar solvent to the liquid and mixing the CdSe colloidal particles dispersed in the liquid into CdSe colloidal agglomerated particles;
(g) recovering the CdSe colloidal agglomerated particles by solid-liquid separation of the liquid;
(h) including a step of adding a nonpolar solvent to the collected CdSe colloidal aggregated particles and mixing them to form a liquid in which the CdSe colloidal particles are dispersed, in the order of the steps (a) to (h) above. Particle production method.   The method for producing CdSe colloidal particles according to claim 1, wherein after the step (h), the steps are repeated once or twice or more from the step (f) to the step (h).

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