Preparation method of efficient luminous silver-indium-sulfur and silver-indium-zinc-sulfur composite nano material

Abstract

The invention discloses a preparation method of an efficient light-emitting silver-indium-sulfur and silver-indium-zinc-sulfur composite nano material, and belongs to the technical field of light-emitting nano materials and preparation. The preparation method comprises the following steps: by taking silver dibutyl dithiocarbamate, indium dibutyl dithiocarbamate and zinc carboxylate as precursors, uniformly mixing at a dodecane neutralization pretreatment temperature to form a mixed solution A; naturally cooling, adding dodecanethiol, and uniformly stirring and mixing to obtain a mixed solution B; at the reaction temperature, decomposing part of silver dibutyldithiocarbamate in the mixed solution B to generate silver sulfide clusters; the activity of the silver sulfide cluster is closely related to the size, the silver sulfide cluster is used as a seed to induce growth of silver-indium-zinc-sulfur, meanwhile, silver sulfide is converted into silver-indium-sulfur, finally, the silver-indium-sulfur and silver-indium-zinc-sulfur composite nano material is obtained, the band gap is 2.0-2.8 eV, the luminous efficiency is 52% or above, and the luminous efficiency can still be kept at 78% or above after five months. The preparation process disclosed by the invention is low in raw material cost and good in process controllability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of luminescent nanomaterials and preparation, and particularly relates to a preparation method of a novel high-efficiency luminescent silver indium sulfide and silver indium zinc sulfide composite nanomaterial. BACKGROUND

[0002] In the field of semiconductor nanomaterials, I-III-VI group semiconductor nanomaterials have unique physicochemical properties and have broad application prospects in the fields of display technology, solar cells, photocatalysis and biological markers. Silver indium sulfide (AgInS2) is a typical representative of I-III-VI group semiconductors, does not contain toxic elements such as cadmium and lead, and is an environmentally friendly direct narrow-bandgap semiconductor. Silver indium sulfide mainly includes low-temperature stable tetragonal phase structure and high-temperature stable orthorhombic phase structure. The difference in phase structure mainly comes from the difference in lattice distortion and atomic order, and the change in phase structure will affect the band gap and photoelectric properties of the material. The band gap of the tetragonal phase silver indium sulfide in the bulk phase is about 1.87 eV, and the band gap of the orthorhombic phase silver indium sulfide is about 2.06 eV. In recent years, the optical performance regulation of silver indium sulfide-based nanomaterials has been a topic of concern for scientists. With the help of size regulation, component engineering and heterojunction interface control, the optical band gap of silver indium sulfide-based nanomaterials is adjusted, and the luminescence wavelength range can cover from the visible light region to the near-infrared region. However, it is still a challenge to achieve high-efficiency luminescence, i.e. brighter, purer and more stable luminescence, which is of great significance for the construction of new silver indium sulfide-based optoelectronic devices.

[0003] There are many synthesis methods for I-III-VI type colloidal nanocrystals, mainly including thermal decomposition, thermal injection, solvothermal method and cation exchange method. Among them, the thermal decomposition of organic precursors is favored due to its simple operation, high controllability of process and suitability for large-scale production. In the process of thermal decomposition, the size, structure and composition of nanocrystals can be adjusted by changing the ratio of precursors, solvents and other reaction parameters. Compared with the most common stable phase chalcopyrite structure in silver indium sulfide, the synthesis of orthorhombic phase structure at low temperature is more difficult. And the orthorhombic phase silver indium sulfide obtained at low temperature often coexists with silver sulfide, and the luminescent performance is not good. In theory, with the help of zinc element doping to passivate the lattice defects in silver indium sulfide and to inhibit the phase separation, it is one of the preferred ways to improve the luminescent performance and stability of silver indium sulfide nanomaterials. However, there are still many difficulties in preparing orthorhombic phase silver indium sulfide-based nanomaterials at low temperature and obtaining high-efficiency luminescent silver indium sulfide and silver indium zinc sulfide composite nanomaterials. The controllable preparation process of high-efficiency luminescent silver indium sulfide and silver indium zinc sulfide composite nanomaterials is urgently needed to be developed. SUMMARY

[0004] In order to obtain a high-efficiency luminescent silver indium sulfide / silver indium zinc sulfide composite nanomaterial, the present application provides a preparation method of silver indium sulfide / silver indium zinc sulfide composite nanomaterial.

[0005] The preparation operation steps of the high-efficiency light-emitting silver indium sulfur and silver indium zinc sulfur composite nanomaterial are as follows: (1) 0.10-0.15 g of silver dibutyldithiocarbamate, 0.12-0.17 g of indium dibutyldithiocarbamate, 0.04-0.13 g of zinc carboxylate and 5 mL of dodecane solvent are stirred uniformly to obtain a mixed solution A; (2) The mixed solution A is kept at 110-115 ℃ for 10-30 min and naturally cooled to room temperature; 1 mL of dodecanethiol is added and stirred uniformly to obtain a mixed solution B; the mixed solution B is kept at 190 ℃ for 60 min to obtain a primary product; (3) The primary product is washed with cyclohexane, ethanol and toluene in sequence for more than twice to collect the product to obtain the high-efficiency light-emitting silver indium sulfur and silver indium zinc sulfur composite nanomaterial; The silver indium sulfur and silver indium zinc sulfur composite nanomaterial is a yellow-brown powder, the band gap size is 2.0-2.8 eV, the light-emitting efficiency is more than 52%, and the light-emitting efficiency can still be maintained at 78% or above after five months.

[0006] Further technical solutions are as follows: In step (1), the zinc carboxylate is zinc stearate or zinc laurate.

[0007] The morphology of the yellow-brown powder of the silver indium sulfur and silver indium zinc sulfur composite nanomaterial is nanorod or nanoparticle, the nanorod material is composed of silver indium sulfur and silver indium zinc sulfur, the content of zinc is 20-41%, the average diameter of the nanorod is 3.2-6.8 nm, and the average length is 8.1-16.2 nm; the nanoparticle material is composed of silver indium sulfur and silver indium zinc sulfur, the content of zinc is less than 20%, and the average diameter of the nanoparticle is 4.5-7.6 nm.

[0008] The beneficial technical effects of the present application are embodied in the following aspects: 1. In the process of preparing the silver indium sulfur and silver indium zinc sulfur composite nanomaterial, silver dibutyldithiocarbamate, indium dibutyldithiocarbamate and zinc carboxylate are used as precursors, the precursors are uniformly mixed in dodecane at a pretreatment temperature to form a uniform mixed solution A; after the mixed solution A is naturally cooled to room temperature, dodecanethiol is continuously added and stirred uniformly to obtain a mixed solution B; at a reaction temperature, part of the silver dibutyldithiocarbamate is decomposed in the mixed solution B to generate silver sulfide (Ag2S) clusters; the activity of the silver sulfide clusters is closely related to the size, and when the silver sulfide clusters are used as seeds to induce the growth of the composite material, the indium dibutyldithiocarbamate and the zinc carboxylate in the mixed solution are first generated into silver sulfide and silver indium zinc sulfide (Ag2S-AgInZnS) under the induction of the silver sulfide (Ag2S) nanoclusters. x S2+x heterojunctions, where small size high active silver sulfide (Ag2S) nanoclusters generate rod-like silver sulfide and silver indium zinc sulfide (Ag2S-AgInZn x S 2+x ) nanocomposites, and large size low active silver sulfide (Ag2S) nanoclusters generate particle-like silver sulfide and silver indium zinc sulfide (Ag2S-AgInZn x S 2+x ) nanocomposites; then the silver sulfide in the generated silver sulfide and silver indium zinc sulfide (Ag2S-AgInZn x S 2+x ) nanocomposites further reacts with indium dibutyl dithiocarbamate to convert into metastable orthorhombic phase silver indium sulfide (AgInS2) structure losing activity, and the final product is rod-like or particle-like silver indium sulfide and silver indium zinc sulfide (AgInZn x S 2+x -AgInS2) nanocomposites; wherein the composition of the rod-like and particle-like silver indium sulfide and silver indium zinc sulfide nanocomposites can be realized within a certain range by adjusting the relative amount of silver dibutyl dithiocarbamate, indium dibutyl dithiocarbamate and zinc carboxylate precursors and the reaction time. The present application provides a new synthetic route for the development of new photoelectric materials. The raw material cost of the preparation process of the present application is low, the process is controllable, the product composition is controllable, the size distribution is uniform, the quality is excellent, the luminous efficiency is high, and it is conducive to the batch production and industrialization of silver indium sulfide and silver indium zinc sulfide nanocomposites.

[0009] 2. The present application uses silver dibutyl dithiocarbamate and indium dibutyl dithiocarbamate with similar molecular structures as silver source and indium source, which to some extent weakens the difference in reactivity of silver ions (Ag + ) and indium ions (In 3+ ); long-chain zinc carboxylate is used as zinc precursor, and the carboxylate and zinc ions are coordinated to form a stable chelate ring structure to inhibit the hydrolysis or oxidation reaction of zinc ions (Zn 2+ ). In the process of preparing silver indium sulfide and silver indium zinc sulfide nanocomposites, part of the silver dibutyl dithiocarbamate precursor is first decomposed into silver sulfide clusters under the action of the mixed solvent, and the silver sulfide clusters act as seeds to induce the growth of the composite material. In the mixed solution, indium dibutyl dithiocarbamate and zinc carboxylate are first generated into silver sulfide and silver indium zinc sulfide (Ag2S-AgInZn x S 2+x ) heterojunctions under the induction of silver sulfide (Ag2S) nanoclusters. The introduction of zinc elements passivates the lattice defects in silver indium sulfide and inhibits phase separation, thereby improving the stability of the heterojunction structure. Then, the generated silver sulfide and silver indium zinc sulfide (Ag2S-AgInZn x S 2+x) and dibutyl indium dithiocarbamate further react, transforming into metastable orthorhombic silver indium sulfide (AgInS2) structure and losing activity, obtaining the final product, i.e. rod-like or granular silver indium sulfide and silver indium zinc sulfide (AgInZn x S 2+x -AgInS2) composite; due to the competition between the induced growth and the transformation of silver sulfide itself, the difference in the reaction activity of silver ions (Ag + ) and indium ions (In 3+ ) is further balanced; the defect density of the final product, i.e. rod-like or granular silver indium sulfide and silver indium zinc sulfide (AgInZn x S 2+x -AgInS2) composite is further reduced, and the luminescent efficiency of the product is further improved; the luminescent efficiency of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial is as high as 52% or more, and the luminescent efficiency can still be maintained at 78% or more after five months, which is far superior to the prior art level. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a transmission electron microscope (TEM) image of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial prepared in Example 1.

[0011] Figure 2 is an X-ray diffraction (XRD) image of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial prepared in Example 1.

[0012] Figure 3 is a high-resolution transmission electron microscope (HRTEM) image of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial prepared in Example 1.

[0013] Figure 4 is a high-angle annular dark-field imaging (HAADF) image of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial prepared in Example 1, nanorods (a) and nanoparticles (b).

[0014] Figure 5 is an ultraviolet-visible (UV-vis) absorption spectrum (a) and a photoluminescence (PL) spectrum (b) of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial prepared in Example 1, and a photoluminescence (PL) spectrum (c) after storage for 5 months.

[0015] Figure 6 is a transmission electron microscope (TEM) image of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial prepared in Example 2.

[0016] Figure 7 is an X-ray diffraction (XRD) image of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial prepared in Example 2.

[0017] Figure 8are UV-vis absorption spectrum (a) and photoluminescence (PL) spectrum (b) of silver indium sulfide and silver indium zinc sulfide composite nanomaterials prepared in Example 2.

[0018] Figure 9 are transmission electron microscope (TEM) images of silver indium sulfide and silver indium zinc sulfide composite nanomaterials prepared in Example 3.

[0019] Figure 10 are X-ray diffraction (XRD) images of silver indium sulfide and silver indium zinc sulfide composite nanomaterials prepared in Example 3.

[0020] Figure 11 are UV-vis absorption spectrum (a) and photoluminescence (PL) spectrum (b) of silver indium sulfide and silver indium zinc sulfide composite nanomaterials prepared in Example 3. DETAILED DESCRIPTION

[0021] The application will be further described below in conjunction with examples. Example 1

[0022] The preparation operation steps of the silver indium sulfide and silver indium zinc sulfide composite nanomaterials with high luminous efficiency are as follows: (1) In a round bottom flask, 0.12 g of silver dibutyl dithiocarbamate, 0.14 g of indium dibutyl dithiocarbamate, 0.13 g of zinc stearate and 5 mL of dodecane were added, mixed and stirred uniformly to obtain a mixed solution A.

[0023] (2) The A solution was kept at 110 ℃ for 10 min and naturally cooled to room temperature; 1 mL of dodecanethiol was added and stirred uniformly to obtain a mixed solution B, which was kept at 190 ℃ for 60 min to obtain a primary product.

[0024] (3) The primary product was sequentially centrifuged and washed twice with cyclohexane, ethanol and toluene, respectively, and the collected product was obtained to obtain the silver indium sulfide and silver indium zinc sulfide composite nanomaterials with high luminous efficiency.

[0025] From Figure 1 It can be seen that the TEM image of the silver indium sulfide and silver indium zinc sulfide composite nanomaterials of the present example 1 shows that the morphology of the product is rod-shaped or granular, the average diameter of the nanorods is 5.1±0.9 nm, the average length is 11.7±1.4 nm, and the average diameter of the nanoparticles is 5.8±0.8 nm. The product size distribution is uniform, and the process of the present application is good in controllability. Figure 2 It can be seen that the characteristic diffraction peak position of the XRD spectrum of the product prepared in the present example 1 is in good agreement with the standard card, indicating that the product is mainly composed of orthorhombic silver indium sulfide (AgInS2) and silver indium zinc sulfide (AgInZnS4). x S 2+x, 1 < x < 10, such as InAgZn7S9) composition. From Figure 3 and Figure 4 It can be seen from the HRTEM image and the HAADF image that the composition of the composite nanomaterial is silver indium sulfide and silver indium zinc sulfide, the structure of the nanorod is shown in a of Figure 4 , and the structure of the nanoparticle is shown in b of Figure 4 . It can be seen from a of Figure 5 , the UV-vis result shows that the absorption shoulder peak of the product is about 582 nm, and the band gap is estimated to be 2.13 eV, Figure 5 , the PL result of b shows that the luminescent performance of the synthesized product is good, the luminescent peak center position is 662 nm, the half-peak width is 89 nm, and the quantum yield is 61%; and Figure 5 , the result of c shows that the stability of the sample is very good, after the sample is stored for 5 months, the luminescent peak center position and the half-peak width remain unchanged, and the quantum yield is 48%. The luminescent efficiency of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial of the embodiment 1 is 61%, and the luminescent efficiency can still be maintained at 78% or above after five months. Embodiment 2

[0026] The preparation operation steps of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial with high luminescent efficiency are as follows: (1) In a round-bottom flask, 0.15 g of silver dibutyldithiocarbamate, 0.17 g of indium dibutyldithiocarbamate, 0.048 g of zinc laurate and 5 mL of dodecane were added, and mixed and stirred uniformly to obtain a mixed solution A.

[0027] (2) The A solution was kept at 115 ℃ for 15 min, and naturally cooled to room temperature; 1 mL of dodecanethiol was added, and stirred uniformly to obtain a mixed solution B, which was kept at 190 ℃ for 60 min to obtain a primary product.

[0028] (3) The primary product was sequentially centrifuged and washed twice with cyclohexane, ethanol and toluene, respectively, and the collected product was obtained to obtain the silver indium sulfide and silver indium zinc sulfide composite nanomaterial with high luminescent efficiency.

[0029] It can be seen from Figure 6 that the TEM image of the silver indium sulfide and silver indium zinc sulfide composite nanomaterial of the embodiment 2 shows that the morphology of the product is rod-shaped or granular, the average diameter of the nanorod is 5.4±1.0 nm, and the average length is 13.2±2.4 nm; the average diameter of the nanoparticle is 5.9±1.3 nm. The size distribution of the product with different morphologies is uniform, and the process of the present application has good controllability. It can be seen from Figure 7 that the characteristic diffraction peak position of the XRD spectrum of the product prepared in the embodiment 1 is well matched with the standard card, which shows that the product is mainly composed of orthorhombic silver indium sulfide (AgInS2) and silver indium zinc sulfide (AgInZn x S 2+x, 1 < x < 10, such as InAgZn7S9. See Figure 8 The UV-vis results in a of the present embodiment 2 show that the absorption shoulder of the product is about 582 nm, and the estimated band gap is 2.13 eV; Figure 8 The PL results in b of the present embodiment 2 show that the synthesized product has good luminescent performance, with the luminescent peak center position being 675 nm and the half-peak width being 96 nm. The luminescent efficiency of the silver indium sulfide and silver indium zinc sulfide composite nanomaterials of the present embodiment 2 is 53%, and the luminescent efficiency can still be maintained at 80% or above after five months. Embodiment 3

[0030] The preparation operation steps of the silver indium sulfide and silver indium zinc sulfide composite nanomaterials with high luminescence are as follows: (1) In a round-bottom flask, 0.10 g of silver dibutyldithiocarbamate, 0.12 g of indium dibutyldithiocarbamate, 0.055 g of zinc stearate, and 5 mL of dodecane were added, and the mixture was uniformly stirred to obtain a mixed solution A.

[0031] (2) The above A solution was kept at 115 ℃ for 10 min and naturally cooled to room temperature; 1 mL of dodecanethiol was added, and the mixture was uniformly stirred to obtain a mixed solution B, which was kept at 190 ℃ for 60 min to obtain a primary product.

[0032] (3) The primary product was sequentially washed twice with cyclohexane, ethanol, and toluene by centrifugation, and the collected product was obtained to obtain the silver indium sulfide and silver indium zinc sulfide composite nanomaterials with high luminescence.

[0033] From Figure 9 It can be seen that the TEM image of the silver indium sulfide and silver indium zinc sulfide composite nanomaterials of the present embodiment 3 shows that the morphology of the product is rod-shaped or granular, the average diameter of the nanorods is 4.4±0.9 nm, and the average length is 10.2±2.0 nm; the average diameter of the nanoparticles is 6.2±0.7 nm. The product has uniform size distribution, and the process of the present embodiment has good controllability. From Figure 10 It can be seen that the characteristic diffraction peak position of the XRD spectrum of the product prepared in the present embodiment 3 is in good agreement with the standard card, indicating that the product is mainly composed of orthorhombic silver indium sulfide (AgInS2) and silver indium zinc sulfide (AgInZn x S 2+x , 1 < x < 10, such as InAgZn7S9. See Figure 11 The UV-vis results in a of the present embodiment 2 show that the absorption shoulder of the product is about 582 nm, and the estimated band gap is 2.13 eV; Figure 11 The PL results in b of the present embodiment 2 show that the synthesized product has good luminescent performance, with the luminescent peak center position being 675 nm and the half-peak width being 96 nm. The luminescent efficiency of the silver indium sulfide and silver indium zinc sulfide composite nanomaterials of the present embodiment 2 is 53%, and the luminescent efficiency can still be maintained at 80% or above after five months.

[0034] It is to be understood that the above-described embodiments are merely illustrative of the principles of the application, and that numerous and various modifications can be made by those skilled in the art without departing from the spirit and scope of the application, and that any such modifications are intended to fall within the scope of the application.

Claims

1. A method for preparing highly efficient luminescent silver-indium-sulfur and silver-indium-zinc-sulfur composite nanomaterials, characterized in that, The operation steps are as follows: (1) Mix 0.10 g to 0.15 g of silver dibutyldithiocarbamate, 0.12 g to 0.17 g of indium dibutyldithiocarbamate, 0.04 g to 0.13 g of zinc carboxylate and 5 mL of dodecane solvent to obtain mixed solution A. (2) The mixed solution A was kept at 110-115 °C for 10-15 min and then naturally cooled to room temperature; 1 mL of dodecanethiol was added and stirred until homogeneous to obtain mixed solution B; the solution was kept at 190 °C for 60 min to obtain the initial product. (3) The primary product was washed twice or more by centrifugation with cyclohexane, ethanol and toluene respectively, and the product was collected to obtain high-efficiency luminescent silver indium sulfide and silver indium zinc sulfide composite nanomaterials. The silver-indium-sulfur and silver-indium-zinc-sulfur composite nanomaterials are yellowish-brown powders with a band gap of 2.0–2.8 eV and a luminous efficiency of over 52%. The luminous efficiency can still be maintained at 78% or above after five months.

2. The method for preparing a high-efficiency luminescent silver-indium-sulfur and silver-indium-zinc-sulfur composite nanomaterial according to claim 1, characterized in that: In step (1), the zinc carboxylate is zinc stearate or zinc laurate.

3. The method for preparing a high-efficiency luminescent silver-indium-sulfur and silver-indium-zinc-sulfur composite nanomaterial according to claim 1, characterized in that: The yellowish-brown powder of the silver-indium-sulfur and silver-indium-zinc-sulfur composite nanomaterial has the morphology of nanorods or nanoparticles. The nanorods are composed of silver-indium-sulfur and silver-indium-zinc-sulfur, wherein the zinc content is 20-41%; the average diameter of the nanorods is 3.2-6.8 nm and the average length is 8.1-16.2 nm; the nanoparticles are composed of silver-indium-sulfur and silver-indium-zinc-sulfur, wherein the zinc content is less than 20%, and the average diameter of the nanoparticles is 4.5-7.6 nm.

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