A stepwise room-temperature preparation method for Ag(In,Ga)S2 quantum dots based on Ag2S templates and its application
By adopting a stepwise preparation method based on Ag2S template, the problems of harsh reaction conditions and complex processes in the preparation of Ag(In,Ga)S2 quantum dots have been solved. A simplified quantum dot preparation method at room temperature has been achieved, and the products have uniform morphology and high brightness, which are suitable for large-scale production and are environmentally friendly.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-12
- Publication Date
- 2026-07-24
AI Technical Summary
The preparation process of Ag(In,Ga)S2 quantum dots in the existing technology generally suffers from problems such as harsh reaction conditions, complex process system, difficulty in balancing component control and surface structure, and difficulty in large-scale preparation. In particular, it is difficult to achieve an efficient and simplified preparation method under room temperature conditions.
A stepwise preparation method based on Ag2S templates was adopted. By first synthesizing Ag2S templates at room temperature, then forming AgInS2 quantum dots and introducing Ga elements sequentially, the stepwise synthesis path was designed. By utilizing the structural reconstruction based on Ag2S templates and the synergistic effect of ligands, the quantum dots were gradually transformed and regulated.
A rapid and simplified preparation of Ag(In,Ga)S2 quantum dots at room temperature was achieved, improving the controllability and reproducibility of the reaction. The products have uniform morphology and high brightness, making them suitable for large-scale production, and the materials are environmentally friendly.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of colloidal semiconductor nanomaterial preparation technology, specifically relating to a room-temperature stepwise preparation method and application of Ag(In,Ga)S2 quantum dots based on Ag2S templates. Background Technology
[0002] Since the discovery of colloidal semiconductor quantum dots, these nanomaterials have attracted widespread attention in fields such as solar cells, light-emitting devices, bioimaging, and biosensing due to their tunable photoelectric properties in terms of size and composition. With the development of colloidal synthetic chemistry, researchers have developed a variety of quantum dot materials with different compositions and structures. Among them, group I-III-VI semiconductor quantum dots have become an important research direction for low-toxicity quantum dots in recent years due to their lower toxicity and better environmental friendliness compared to cadmium-based and lead-based quantum dots. AgInS2 quantum dots, as a representative system, have a large Stokes shift, tunable luminescence properties, and good application prospects. Ag(In,Ga)S2 quantum dots, formed by further introducing Ga elements into AgInS2, show potential for further improvement in terms of bandgap tuning, emission wavelength adjustment, surface state optimization, and stability enhancement.
[0003] In existing technologies, the preparation of Ag(In,Ga)S2 quantum dots still mainly employs a high-temperature organic phase synthesis route. Relevant published literature indicates that this type of method typically achieves the formation of Ag(In,Ga)S2 quantum dots by adjusting the reactivity of silver, indium, and gallium precursors, the ligand environment, and the reaction temperature, and further improves luminescence performance through surface passivation. Although this type of method can achieve high luminescence efficiency, it usually relies on high temperatures, complex precursor systems, or post-processing steps, requiring high levels of process control.
[0004] Template methods or cation exchange methods are also important construction routes for group I-III-VI quantum dots. Previous studies have reported the ability to first prepare binary Ag₂S quantum dots and then use In… 3+ With Ag + Some studies have yielded AgInS2 quantum dots through partial cation exchange; others have disclosed a technical route for preparing AgInS2-based nanocrystals via cation exchange using In2S3 as a template. These techniques demonstrate that using pre-prepared binary sulfide nanocrystals as structural templates, and then constructing ternary quantum dots through subsequent cation exchange or component transformation, is theoretically feasible.
[0005] However, for Ag(In,Ga)S2 quantum dots, existing technologies mainly focus on direct synthesis with high-temperature organic phases, reactive matching synthesis, or subsequent surface passivation to improve quantum yield. Existing publicly available methods primarily address how to improve luminescence performance through precursor reactivity regulation, zinc halide passivation, or shell growth. A technical route for forming Ag(In,Ga)S2 quantum dots using Ag2S as a template under relatively mild conditions, especially room temperature, through stepwise component conversion has not yet been disclosed.
[0006] Meanwhile, the formation process of multi-component Ag(In,Ga)S2 quantum dots typically involves the diffusion, exchange, and lattice reconstruction of multiple cations such as Ag, In, and Ga. The introduction of Ga not only affects the band gap and emission wavelength of the product but also influences surface defect states, local component distribution, and crystal growth kinetics. If a one-step method or a high-temperature rapid reaction method is still used, it is often difficult to simultaneously achieve uniformity in component introduction, controllability of surface structure, and batch stability, thus hindering process simplification and scale-up preparation. This problem is particularly prominent at room temperature.
[0007] Therefore, in view of the problems that the existing Ag(In,Ga)S2 quantum dot preparation process generally has, such as harsh reaction conditions, complex process system, difficulty in balancing component control and surface structure, and difficulty in large-scale preparation, it is necessary to provide a method that is simple, low-cost, reproducible and suitable for large-scale preparation of Ag(In,Ga)S2 quantum dots. Summary of the Invention
[0008] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a room-temperature stepwise preparation method for Ag(In,Ga)S2 quantum dots based on Ag2S templates. This method features mild reaction conditions, can be completed within seconds, is simple, has good reproducibility, and can achieve at least 40-fold scale-up preparation with gram-level yields. The prepared Ag(In,Ga)S2 quantum dots exhibit uniform morphology and high brightness. This invention provides a new method for low-cost, large-scale preparation of high-brightness Ag(In,Ga)S2 quantum dots, and has promising commercial application prospects.
[0009] The first objective of this invention is to provide a room-temperature stepwise preparation method for Ag(In,Ga)S2 quantum dots based on Ag2S templates, comprising: The sulfur solution was mixed with the silver precursor and stirred at room temperature for 1-5 hours to obtain the Ag2S template. At room temperature, an indium source was added to methanol to obtain an indium solution. Ag2S template, toluene, n-dodecyl mercaptan and octylamine were mixed and stirred for 1 min. Then, the indium solution and phosphine ligand were added dropwise and the reaction was stirred for 1-5 hours to obtain AgInS2 quantum dots. At room temperature, toluene, a gallium source, n-dodecyl mercaptan, and AgInS2 quantum dots were mixed, and a phosphine-based ligand was added dropwise. The mixture was stirred for 1-5 hours to obtain Ag(In,Ga)S2 quantum dots. Further, the silver precursor was prepared by mixing a silver source, octylamine, and toluene and stirring until a transparent solution was formed.
[0010] Furthermore, the silver source is any one of silver iodide (AgI), silver acetate (AgAc), and silver nitrate (AgNO3).
[0011] Furthermore, the sulfur solution is prepared by ultrasonically mixing a sulfur source and toluene until the sulfur source is completely dissolved.
[0012] Furthermore, the sulfur source is sulfur powder or thiourea.
[0013] Furthermore, the molar ratio of the silver source to the sulfur source is 2:1.
[0014] Furthermore, the molar ratio of the silver source to the indium source is 1:1; Furthermore, the indium source is any one of indium acetate (In(Ac)3), indium chloride (InCl3), indium triacetylacetonate (In(acac)3), and indium nitrate (In(NO3)3).
[0015] Furthermore, the molar ratio of the AgInS2 quantum dots to the gallium source is 1:1; Furthermore, the gallium source is any one of gallium chloride (GaCl3), gallium triacetylacetonate (Ga(acac)3), and gallium iodide (GaI3).
[0016] Furthermore, the phosphine-based ligand is any one of trioctylphosphine, triphenylphosphine, and trioctylphosphine oxide.
[0017] A second objective of this invention is to provide an Ag(In,Ga)S2 quantum dot prepared according to any of the methods described above.
[0018] Furthermore, the emission peak position range of the Ag(In,Ga)S2 quantum dots is 600~900 nm.
[0019] A third objective of this invention is to provide an application of the above-mentioned Ag(In,Ga)S2 quantum dots in the fields of light-emitting devices, displays, photoelectric detection, and biomarkers.
[0020] Compared with the prior art, the advantages of this invention are as follows: (1) This invention designs a three-step synthesis path by first synthesizing Ag2S template nanocrystals, then sequentially completing the formation of AgInS2 quantum dot intermediates and the introduction of Ga elements. This transforms the formation of multi-element quantum dots from a complex one-step nucleation growth process into a step-by-step transformation process, which is beneficial to improving the controllability of the reaction process and reducing the risk of component imbalance and side reactions caused by the simultaneous reaction of multiple metal ions. Moreover, Ag(In,Ga)S2 quantum dots can be prepared at room temperature without the need for complex processes such as high-temperature injection and long-term heating reaction, which is beneficial to reducing the dependence on high-temperature reaction kinetics, thereby achieving mild reaction conditions, short reaction time and simplified process. It is also beneficial to improve the reproducibility between different batches and provide a foundation for subsequent large-scale preparation.
[0021] (2) This invention synthesizes AgInS2 quantum dots based on Ag2S templates. Since Ag2S templates are monoclinic and AgInS2 quantum dots are tetragonal, the synthesis of AgInS2 quantum dots based on Ag2S templates in this invention is not simply a matter of synthesizing Ag... + With In 3+ The transformation process does not involve cation exchange, but is accompanied by a structural reconstruction from a monoclinic lattice to a tetragonal lattice. This structural change indicates that Ag₂S template nanocrystals can undergo rearrangement and reconstruction during the transformation, which is beneficial for forming new AgInS₂ quantum dot crystal structures. Compared to the one-step direct reaction to form multi-component quantum dots, the Ag₂S template-induced reconstruction method of this invention is more conducive to achieving controllable transformation under milder conditions, and is also beneficial for further refining the original particles, inhibiting excessive particle growth, and improving the particle size distribution of the final product. Therefore, this invention is beneficial for obtaining quantum dot products with more uniform morphology and more concentrated size distribution.
[0022] (3) This invention focuses the main crystal structure transformation in the second step of converting the Ag2S template into AgInS2 quantum dots. Since both AgInS2 and Ag(In,Ga)S2 quantum dots are tetragonal, the introduction of Ga in the third step is a further adjustment within the same crystal system framework, without undergoing a new large-scale crystal form change. This reduces the structural disorder and defect accumulation problems caused by multiple elements participating in the reaction and inducing lattice reconstruction simultaneously in the traditional one-step method. It is beneficial to improve the controllability of Ga element introduction and the structural stability of the generated Ag(In,Ga)S2 quantum dots, and to maintain their optical performance and material reliability. Moreover, the synergistic effect of dodecyl mercaptan and phosphine ligands is also beneficial to stabilizing the reaction intermediates and the quantum dot surface, reducing surface dangling bonds and defect states, thereby reducing nonradiative recombination loss and improving the luminescence brightness of the quantum dots.
[0023] (4) Because the present invention adopts a reaction method that combines template induction and stepwise control, the quantum dot formation path is clearer and the key conversion steps are easier to control, which is beneficial to improving the reproducibility between different batches. At the same time, the method can be completed quickly at room temperature, which also helps to reduce the equipment burden and operational complexity during process scale-up, providing a foundation for subsequent large-scale preparation.
[0024] (5) The Ag(In,Ga)S2 quantum dots prepared by this invention belong to the I-III-VI group of low-toxicity semiconductor quantum dots. They do not contain highly toxic heavy metal elements such as cadmium and lead. While maintaining high luminous brightness and good structural stability, they also have good environmental friendliness. Therefore, they have good application potential in the fields of light-emitting devices, displays, photoelectric detection, and biological labeling. Attached Figure Description
[0025] Figure 1 Transmission electron microscope image of monoclinic Ag2S quantum dots prepared for this invention.
[0026] Figure 2 Transmission electron microscope image of orthogonal AgInS2 quantum dots prepared according to the present invention.
[0027] Figure 3 Transmission electron microscope image of orthogonal Ag(In,Ga)S2 quantum dots prepared in this invention.
[0028] Figure 4 X-ray diffraction patterns of monoclinic Ag2S, orthogonal AgInS2 quantum dots, and orthogonal Ag(In,Ga)S2 quantum dots prepared according to the present invention.
[0029] Figure 5 The normalized absorption and fluorescence spectra of the AgInS2 quantum dots prepared in this invention are shown.
[0030] Figure 6 The normalized absorption and fluorescence spectra of Ag(In,Ga)S2 quantum dots prepared by the reaction of the present invention for 1 min are shown. The upper right corner is a photograph of Ag(In,Ga)S2 quantum dots under a UV lamp.
[0031] Figure 7 The normalized absorption and fluorescence spectra of the Ag(In,Ga)S2 quantum dots prepared in this invention are shown.
[0032] Figure 8 The fluorescence spectra of Ag(In,Ga)S2 quantum dots and AgInS2 quantum dots prepared in this invention are shown; the red curve represents Ag(In,Ga)S2 quantum dots and the black curve represents AgInS2 quantum dots. Detailed Implementation
[0033] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.
[0034] Example 1 This invention provides a room-temperature stepwise preparation method for Ag(In,Ga)S2 quantum dots based on an Ag2S template, specifically including: Step 1: Mix the sulfur solution with the silver precursor and stir rapidly for 2 hours at room temperature (20~30℃, preferably 25℃) to obtain the Ag2S template; In this embodiment, the silver precursor is prepared by mixing 1 mmol of AgNO3, 1.25 mL of octylamine and 5 mL of toluene in a sample vial and stirring thoroughly until a transparent solution is formed.
[0035] In this embodiment, the sulfur solution was prepared by mixing 0.5 mmol of sulfur powder and 2.5 mL of toluene in a sample vial and then thoroughly ultrasonicating until the sulfur source was completely dissolved.
[0036] Step 2: At room temperature (20~30℃, preferably 25℃), 1 mmol of In(NO3)3 was added to 1 mL of methanol to obtain an indium solution. 0.5 mmol of Ag2S template, 2 mL of toluene, 1.2 mL of n-dodecyl mercaptan and 640 μL of octylamine were mixed and stirred for 1 min. Then, the indium solution and 0.45 mL of trioctylphosphine were slowly added dropwise. After 5 s, the solution immediately turned red. The reaction was stirred for 5 hours to obtain AgInS2 quantum dots. Step 3: At room temperature (20~30℃, preferably 25℃), mix 2 mL of toluene, 0.1 mmol of GaCl3, 0.12 mL of n-dodecyl mercaptan and 0.1 mmol of AgInS2 quantum dots in a sample vial, and slowly add 0.09 mL of trioctylphosphine. After 5 seconds, the solution immediately turns orange. Stir the reaction for 5 hours to obtain Ag(In,Ga)S2 quantum dots.
[0037] Example 2 This embodiment provides a room-temperature stepwise preparation method for Ag(In,Ga)S2 quantum dots based on Ag2S templates. The specific steps are basically the same as those in Example 1, except that the stirring times in steps 1 to 3 are 1 hour, 2 hours and 2 hours, respectively.
[0038] Example 3 This embodiment provides a room-temperature stepwise preparation method for Ag(In,Ga)S2 quantum dots based on Ag2S templates. The specific steps are basically the same as those in the previous embodiment, except that the stirring times in steps 1 to 3 are 5 hours, 1 hour, and 1 hour, respectively.
[0039] The Ag(In,Ga)S2 quantum dots provided in Example 1 of this invention are characterized in terms of structure and performance.
[0040] 1. Experimental apparatus Absorption spectra were determined using a Metalash UV-8000 spectrophotometer. Fluorescence spectra and fluorescence quantum yields (PLQYs) were determined using an Edinburgh FLS1000 fluorometer equipped with an integrating sphere. Transmission electron microscopy (TEM) images were obtained using a Thermo Fisher Scientific Spectra 300 S / TEM. Powder XRD patterns were acquired using a Bruker D8 Advance diffractometer (CuKα, λ = 1.5406 Å).
[0041] 2. Experimental Results pass Figure 1 It can be seen that the synthesized Ag2S quantum dots are spherical quantum dots with somewhat uneven size, averaging about 5 nm in diameter. Figure 2 It can be seen that the synthesized AgInS2 quantum dots are uniform in size, with a spherical morphology and an average particle size of approximately 3.7 nm. Figure 3 It can be seen that the synthesized Ag(In,Ga)S2 quantum dots have a spherical morphology, and their size is clearly consistent with that of AgInS2 quantum dots, indicating that they will not split further. Furthermore, relatively obvious and continuous lattice fringes can be observed, demonstrating good crystallinity.
[0042] pass Figure 4 It can be seen that Ag2S quantum dots match PDF#24-0715, exhibiting a monoclinic crystal structure; AgInS2 quantum dots match PDF#025-1328; and Ag(In,Ga)S2 quantum dots match PDF#00-057-0358. Both AgInS2 and Ag(In,Ga)S2 quantum dots are tetragonal. Figure 5 The AgInS2 quantum dot was shown to emit defect states with FHWM=129nm, peak position at 684nm, and PLQY=8%. Figure 6 and Figure 7 The normalized absorption and fluorescence spectra of Ag(In,Ga)S2 quantum dots obtained by stirring for 1 min and 5 hours respectively in step 3 of Example 1 of the present invention are shown below; Figure 6The results show that the Ag(In,Ga)S2 (i.e., AIGS) quantum dots obtained by stirring for 1 min exhibit defect state emission with FHWM=129nm and peak position at 648nm.
[0043] pass Figure 7 The Ag(In,Ga)S2 quantum dots obtained by stirring for 5 hours showed defect state emission with FHWM = 120 nm, peak position at 616 nm, and PLQY = 48%. Figure 8 This indicates that Ag(In,Ga)S2 quantum dots were prepared by introducing Ga element into AgInS2 quantum dots under the synergistic effect of n-dodecylthiol and phosphine ligands. Furthermore, the introduction of Ga element resulted in a significant blue shift of the luminescence center from the near-infrared region. The fluorescence spectral peak positions of Ag(In,Ga)S2 quantum dots differed from those of AgInS2 quantum dots by 68 nm.
[0044] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.
Claims
1. A room-temperature stepwise method for preparing Ag(In,Ga)S2 quantum dots based on Ag2S templates, characterized in that, include: The sulfur solution was mixed with the silver precursor and stirred at room temperature for 1-5 hours to obtain the Ag2S template. At room temperature, an indium source was added to methanol to obtain an indium solution. Ag2S template, toluene, n-dodecyl mercaptan and octylamine were mixed and stirred for 1 min. Then, the indium solution and phosphine ligand were added dropwise and the reaction was stirred for 1-5 hours to obtain AgInS2 quantum dots. At room temperature, toluene, gallium source, n-dodecyl mercaptan and AgInS2 quantum dots were mixed and phosphine-based ligands were added dropwise. The mixture was stirred for 1-5 hours to obtain Ag(In,Ga)S2 quantum dots.
2. The method according to claim 1, characterized in that, The silver precursor is prepared by mixing and stirring a silver source, octylamine, and toluene until a transparent solution is formed.
3. The method according to claim 2, characterized in that, The silver source is any one of silver iodide, silver acetate, or silver nitrate.
4. The method according to claim 2, characterized in that, The sulfur solution is prepared by ultrasonically mixing a sulfur source and toluene until the sulfur source is completely dissolved.
5. The method according to claim 4, characterized in that, The sulfur source is sulfur powder or thiourea.
6. The method according to claim 4, characterized in that, The molar ratio of the silver source to the sulfur source is 2:
1.
7. The method according to claim 1, characterized in that, The molar ratio of the silver source to the indium source is 1:1; The indium source is any one of indium acetate, indium chloride, indium triacetylacetonate, and indium nitrate.
8. The method according to claim 1, characterized in that, The molar ratio of the AgInS2 quantum dots to the gallium source is 1:1; The gallium source is any one of gallium chloride, gallium triacetylacetonate, and gallium iodide.
9. Ag(In,Ga)S2 quantum dots prepared by the method according to any one of claims 1-8.
10. The use of Ag(In,Ga)S2 quantum dots according to claim 9 in the fields of light-emitting devices, displays, photoelectric detection, and biomarking.