A method for preparing lead halide semiconductor thin films from waste lead paste

Abstract

This invention discloses a method for preparing lead halide semiconductor thin films from waste lead paste. The method includes the following steps: A: Thoroughly cleaning the substrate, followed by drying; B: Collecting a portion of lead paste from waste lead-acid batteries, first using a desulfurizing agent to desulfurize the lead paste with lead sulfate, then adding a reducing agent to convert lead dioxide into lead oxide, and then using an organic acid leaching agent to obtain an acid solution containing divalent lead ions; C: Depositing the acid solution containing divalent lead ions and a certain amount of halogenated acid or halide salt onto the treated substrate, then placing the substrate on a hot plate for high-temperature annealing, obtaining the lead halide semiconductor thin film after annealing, and then drying it in a drying oven. This method not only simplifies the steps and directly yields lead halide thin films, reducing excessive waste of lead resources, but also promotes the large-scale application of optoelectronic devices with the obtained lead halide thin films.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor materials, and specifically relates to a method for preparing lead halide semiconductor thin films from waste lead paste. Background Technology

[0002] Optoelectronic devices are a class of devices based on the photoelectric conversion properties of semiconductor materials. They are currently widely used in commercial and scientific fields, particularly in photoelectric detection, video imaging, light-emitting displays, and photovoltaics, where they have attracted considerable attention. Developing semiconductor materials with excellent photoelectric properties is key to obtaining high-performance optoelectronic devices. Among many semiconductor materials, lead halides, with their large bandgap and high carrier mobility, have become a key material not only for radiation detectors but also for perovskite solar cells. Currently, there are two main methods for preparing lead halide thin films: physical vapor deposition (PVD) and solution deposition. PVD technology is complex and costly, while solution deposition allows for low-temperature operation and low-cost production. However, current solution-based lead halide thin films typically require the use of toxic polar organic solvents. The film-forming process necessitates heating and annealing to remove residual solvents from the film, which can easily cause environmental pollution and health hazards. In addition, the source of lead-containing raw materials in the preparation and production process of lead halide semiconductor materials also needs to be carefully considered. Currently, lead compounds obtained from lead mineral metallurgy are still used as raw materials, and there is an urgent need for low-carbon and environmentally friendly alternative lead sources.

[0003] In the past, lead-acid batteries greatly promoted the development of electrical equipment, and their low price and safety advantages led to their widespread use in the market. However, with the emergence of new high-energy-density batteries, the number of lead-acid batteries replaced and scrapped each year has also increased. Waste lead-acid batteries contain a large amount of lead, and if not properly recycled, they not only cause serious resource waste but also pose a serious threat to the ecological environment and human health. Currently, waste lead-acid battery recycling is mainly based on pyrometallurgical and hydrometallurgical processes. Pyrometallurgical processes consume a lot of energy and generate polluting gases, causing environmental pollution, while hydrometallurgical processes have received widespread attention due to their low energy consumption and low pollution emissions. From a green environmental protection perspective, recycling the lead source from waste lead-acid batteries as a raw material for lead halide thin films can realize the recycling of lead resources and alleviate the environmental pressure caused by waste lead pollution. Therefore, the recycling of lead-acid batteries provides an alternative and readily available lead source for the preparation of high-performance, low-cost lead halide semiconductor optoelectronic devices. Summary of the Invention

[0004] To overcome the shortcomings of the existing technology, the present invention provides a method for preparing lead halide semiconductor thin films from waste lead paste.

[0005] To achieve the above objectives, the present invention provides a method for preparing lead halide semiconductor thin films from waste lead paste, comprising the following steps:

[0006] A: Thoroughly clean the substrate, and then dry it.

[0007] B: Collect some lead paste from waste lead-acid batteries. First, use a desulfurizing agent to desulfurize the lead paste with lead sulfate. Then, add a reducing agent to convert lead dioxide into lead oxide. Finally, use an organic acid leaching agent to obtain an acid solution containing divalent lead ions.

[0008] C: An acid solution containing divalent lead ions and a certain amount of halogenated acid or halogenated salt are deposited together on the treated substrate. The substrate is then placed on a hot plate for high-temperature annealing. After annealing, a lead halide semiconductor thin film is obtained and placed in a drying oven for drying.

[0009] Preferably, the substrate is a rigid substrate or a flexible substrate.

[0010] Preferably, the rigid substrate comprises a glass sheet or a silicon wafer.

[0011] Preferably, the flexible substrate comprises metal foil or PET.

[0012] Preferably, the thorough cleaning step in step A includes: (1) ultrasonic cleaning with glass cleaner, acetone, alcohol and deionized water for 10-20 minutes in sequence; (2) ultraviolet ozone treatment for 15-30 minutes.

[0013] Preferably, the lead-containing compound in the lead paste is one or more of lead oxide, lead dioxide, and lead sulfate.

[0014] Preferably, in step B, the desulfurizing agent is one or more of sodium carbonate, ammonium carbonate, sodium acetate, ammonium acetate, sodium citrate, and ammonium citrate; the reducing agent is one or more of hydrogen peroxide, sodium sulfite, oxalate, and ascorbic acid; the organic acid leaching agent is an aqueous solution of one or more of acetic acid, oxalic acid, and citric acid; and the concentrations of the desulfurizing agent, reducing agent, and organic acid leaching agent are 20-90%, respectively.

[0015] Preferably, the halogenated acid in step C is one or more of hydroiodic acid and hydrobromic acid, and the halogenated salt is one or more of potassium iodide, sodium iodide, and sodium bromide.

[0016] Preferably, the deposition method in step C is one or more of spin coating, blade coating, and slot coating.

[0017] Preferably, in step C, the temperature of the heating platform is 50-150°C.

[0018] Compared with the prior art, the main advantages of this invention are:

[0019] (1) The present invention proposes a method for preparing lead halide films from waste lead paste, which extracts lead halides in a pollution-free and mild reaction condition, thus solving the problems of high cost and complex operation in the traditional lead halide film preparation process.

[0020] (2) This preparation method can achieve the preparation of large-size lead halide thin films with high yield and controllable process in a short process, which can promote the large-scale application of optoelectronic devices.

[0021] (3) For the preparation of lead halide films, toxic organic solvents such as dimethylformamide and dimethyl sulfoxide are removed, which effectively simplifies the experimental steps and has environmentally friendly characteristics. Attached Figure Description

[0022] Figure 1 This is a microscopic morphology image of the lead iodide thin film prepared in Example 1 of the present invention.

[0023] Figure 2 This is the X-ray diffraction pattern of the lead iodide thin film obtained in Example 1 of the present invention. Detailed Implementation

[0024] To make the content of this invention easier to understand, the technical solutions of this invention will be further described below in conjunction with specific embodiments and accompanying drawings, but this invention is not limited thereto.

[0025] Example 1:

[0026] Step 1: Take 3g of lead paste obtained from waste lead-acid batteries, place it in a round-bottom flask, pour in 50mL of 60% sodium carbonate aqueous solution, heat the solution to 90℃, and stir continuously for 2 hours; after the solution cools to room temperature, add 20% hydrogen peroxide to carry out the reduction reaction, and then slowly add 50% acetic acid aqueous solution to make the solution clear.

[0027] Step 2: Use glass cleaner, acetone, alcohol and deionized water to ultrasonically clean the blank soda-lime glass substrate in sequence; after cleaning, blow the glass substrate dry with inert gas and place it in a UV-ozone generator for 15-25 minutes; then put it in a drying oven to dry thoroughly.

[0028] Step 3: Using two pipettes, simultaneously drop 30 μL of the clear solution and 70 μL of hydroiodic acid onto a glass substrate, allowing them to stand and spread out. Spin-coat the mixed solution onto the glass substrate at 2000 rpm, and anneal at 70°C for 30 min to obtain a lead iodide film. The microstructure of the obtained lead iodide film is shown below. Figure 1 As shown, the X-ray diffraction (XRD) of the thin film is as follows: Figure 2As shown, the film surface is relatively dense; XRD shows that the film phase is lead iodide, with no other impurity phases.

[0029] Example 2:

[0030] Step 1: Take 5g of lead paste obtained from waste lead-acid batteries and place it in a round-bottom flask. Mix 0.5g of ammonium acetate and 1g of sodium sulfite in 80mL of dilute acetic acid (0.4mol / mL) to obtain a mixed solution. Add the mixed solution to the round-bottom flask and stir continuously at 35℃ for 24 hours to simultaneously achieve desulfurization, reduction and leaching of the lead paste, obtaining a lead acetate solution.

[0031] Step 2: Use glass cleaner, acetone, alcohol, and deionized water to ultrasonically clean the silicon wafer in sequence. After cleaning, blow the silicon wafer dry with inert gas and place it in a UV-ozone generator for 15-25 minutes. Then, put it in a drying oven to dry it thoroughly.

[0032] Step 3: Using two pipettes, simultaneously drop 40 μL of clear lead acetate solution and 80 μL of hydrobromic acid onto the silicon wafer, and allow them to stand and spread out. Spin-coat the mixed solution onto the silicon wafer at 3000 rpm, and anneal at 50°C for 40 min to obtain a lead bromide film.

[0033] Example 3:

[0034] Step 1: Take 10g of lead paste obtained from waste lead-acid batteries, place it in a round-bottom flask, pour in 200mL of 60% sodium carbonate aqueous solution, heat the solution to 90℃, and stir continuously for 2 hours; after the solution cools to room temperature, add 20% sodium oxalate to carry out the reduction reaction, and then slowly add 50% excess oxalic acid aqueous solution to make the solution clear and obtain a lead ion-containing solution.

[0035] Step 2: Use glass cleaner, acetone, alcohol and deionized water to ultrasonically clean the ITO-coated glass substrate in sequence; after cleaning, blow the ITO glass substrate dry with inert gas and place it in a UV-ozone generator for 15-25 minutes; then put it in a drying oven to dry thoroughly.

[0036] Step 3: A lead iodide film was prepared using a slit coating process. The solutions were a treated clear lead solution and a 20% hydroiodic acid aqueous solution. The main parameters for slit coating were set as follows: the height of the coating blade from the substrate was 30 μm, the stage temperature was 25 °C, the stage moving speed was 10 mm / s, and the injection speed of the injection system was 1.5 ml / min. First, a lead solution film was coated, followed by the hydroiodic acid aqueous solution coating on top of the lead solution film. The resulting mixed film was then rapidly placed on a hot plate for annealing at 150 °C for 15 min, yielding the lead iodide film.

Claims

1. A method for preparing lead halide semiconductor thin films from waste lead paste, characterized in that, Includes the following steps: A: Thoroughly clean the substrate, and then dry it. B: Collect some lead paste from waste lead-acid batteries. First, use a desulfurizing agent to desulfurize the lead paste with lead sulfate. Then, add a reducing agent to convert lead dioxide into lead oxide. Finally, use an organic acid leaching agent to obtain an acid solution containing divalent lead ions. In step B, the desulfurizing agent is one or more of sodium carbonate, ammonium carbonate, sodium acetate, ammonium acetate, sodium citrate, and ammonium citrate; the reducing agent is one or more of hydrogen peroxide, sodium sulfite, oxalate, and ascorbic acid; the organic acid leaching agent is an aqueous solution of one or more of oxalic acid and citric acid; the concentrations of the desulfurizing agent, reducing agent, and organic acid leaching agent are 20-90%. C: An acid solution containing divalent lead ions and a certain amount of halogenated acid or halogenated salt are deposited together on the treated substrate. The substrate is then placed on a hot stage for high-temperature annealing. After annealing, a lead halide semiconductor thin film is obtained and placed in a drying oven for drying. The deposition method in step C is one or more of spin coating, blade coating, and slot coating. The temperature of the hot stage is 50-150℃.

2. The method for preparing lead halide semiconductor thin films from waste lead paste as described in claim 1, characterized in that, The substrate can be a rigid substrate or a flexible substrate.

3. The method for preparing lead halide semiconductor thin films from waste lead paste as described in claim 2, characterized in that, The rigid substrate includes a glass sheet or a silicon wafer.

4. The method for preparing lead halide semiconductor thin films from waste lead paste as described in claim 2, characterized in that, The flexible substrate includes metal foil or PET.

5. The method for preparing lead halide semiconductor thin films from waste lead paste as described in claim 1, characterized in that, The thorough cleaning steps in step A include: (1) ultrasonic cleaning with glass cleaner, acetone, alcohol and deionized water for 10-20 minutes in sequence; (2) ultraviolet ozone treatment for 15-30 minutes.

6. The method for preparing lead halide semiconductor thin films from waste lead paste as described in claim 1, characterized in that, The lead-containing compound in the lead paste is one or more of lead oxide, lead dioxide, and lead sulfate.

7. The method for preparing lead halide semiconductor thin films from waste lead paste as described in claim 1, characterized in that, The halogenated acid in step C is one or more of hydroiodic acid and hydrobromic acid, and the halogenated salt is one or more of potassium iodide, sodium iodide, and sodium bromide.

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