CN113061837A

CN113061837A - Preparation method of high-transparency p-type cuprous iodide conductive film

Info

Publication number: CN113061837A
Application number: CN202110311867.9A
Authority: CN
Inventors: 孙珲; 罗淑林; 宫建红
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2021-03-24
Filing date: 2021-03-24
Publication date: 2021-07-02

Abstract

The invention relates to the technical field of conductive films, and discloses a preparation method of a high-transparency p-type cuprous iodide conductive film, which comprises the following steps: s1, substrate cleaning: cleaning the substrate, and drying the substrate by using nitrogen for later use; s2, preparing a precursor film: attaching the substrate subjected to the step S1 on a sample holder of radio frequency magnetron sputtering equipment, and performing magnetron sputtering by using a copper metal target as a sputtering target material to deposit and form Cu₃N film, then taking out Cu₃N film; s3, preparing a CuI film: weighing quantitative iodine simple substance to enable the iodine simple substance to form gas-phase iodine and Cu₃And carrying out iodination on the N film to obtain the CuI film. The invention forms Cu by magnetron sputtering₃N thin film precursorPassing the gas phase of elemental iodine and Cu₃The transparent CuI conductive film is prepared by carrying out iodination reaction on the N film, the volume expansion multiple of the cuprous iodide film is reduced, the transparency, the conductivity and the controllability of the conductive film are improved, direct contact with solid or liquid iodine is not needed, the surface iodine residue is reduced, the process is simple, and the cost is low.

Description

Preparation method of high-transparency p-type cuprous iodide conductive film

Technical Field

The invention relates to the technical field of conductive films, in particular to a preparation method of a high-transparency p-type cuprous iodide conductive film.

Background

The Transparent Conductive Material (TCM) is a material having conductivity close to that of metal and high transmittance in a visible light region. The method is widely applied to the fields of solar cells, displays, light emitting diodes, light detection equipment and the like. The p-type transparent conductive material is slow in development, poor in electrical and optical properties and high in preparation cost, and greatly limits the development of active and passive transparent and flexible electronic devices. Especially, in recent years, transparent flexible displays, wearable communication devices, smart medical wearable devices, and the like are favored, and the development of these devices is still far from excellent p-type transparent conductive materials.

CuI is one of the most promising transparent p-type semiconductor materials. The zinc blende structure (gamma-CuI) is in a zinc blende structure at normal temperature, and the direct energy band width of the zinc blende structure is 3.1eV, so that the zinc blende structure can obtain high transmittance in a visible light band; its carrier mass is only 0.3m₀Making it possible to obtain high electrical conductivity. And the preparation method also has the advantages of no toxicity, environmental protection, rich storage of constituent elements, low-temperature preparation and the like.

At present, the gas-phase iodination method is an ideal method for preparing the CuI film, and has the advantages of simple operation, low preparation temperature, low cost and the like. Which uses a CuI film prepared by reacting a Cu film with iodine (here, iodine gas, iodine solid, or iodine solution). However, the volume expansion (5 to 9 times) of the Cu precursor film after iodination causes the prepared CuI film to have a rough surface and the appearance of ground glass, and the transparency of the CuI film is poor. And the high volume expansion factor makes the controllability of the film thickness poor. In addition, when solid or liquid iodination and other contact type iodination are carried out, the precursor film needs to be directly contacted with solid iodine or iodine liquid, the influence of the contact area on the film quality is large, and the repeatability is poor; the prepared film has a large amount of iodine residues on the surface, which is inconvenient for subsequent cleaning and processing, causes difficulty in controlling the film components and influences the film quality. For example, heating changes the original crystalline state and electrical properties of the CuI film; the liquid cleaning may reduce the film-substrate bonding force of the CuI film or part of the film layer may fall off. In addition, this contact iodination method is not suitable for the production of large-sized thin films and mass production.

Disclosure of Invention

In order to solve the technical problem, the invention provides a preparation method of a high-transparency p-type cuprous iodide conductive film, which comprises the following steps:

s1, substrate cleaning: cleaning the substrate, and then blowing the substrate by using nitrogen for later use;

s2, preparation of a precursor film: attaching the substrate subjected to the step S1 on a sample holder of radio frequency magnetron sputtering equipment, and performing magnetron sputtering by using a copper metal target as a sputtering target material to deposit and form Cu₃N film, then taking out Cu₃N film;

s3, preparing a CuI film: weighing quantitative iodine simple substance, sublimating the iodine simple substance to form gas-phase iodine, and mixing the gas-phase iodine with the Cu₃And carrying out iodination on the N film to obtain the CuI film.

Preferably, in step S1, the substrate refers to a glass substrate or a plastic substrate, so as to obtain a p-type cuprous iodide conductive film suitable for different materials.

Preferably, the plastic substrate is any one of a PET (polyethylene terephthalate) film, PEN (polyethylene naphthalate), PI (polyimide), PC (polycarbonate), PVDF (polyvinylidene fluoride), PDMS (polydimethylsiloxane).

Preferably, the cleaning agent used for cleaning the substrate in step S1 includes an organic solvent and deionized water, wherein the organic solvent includes one or two of acetone and absolute ethyl alcohol, so as to clean the substrate of different materials. Specifically, the organic solution used for cleaning the glass substrate is acetone and absolute ethyl alcohol, and the organic solvent used for cleaning the plastic substrate is absolute ethyl alcohol.

Preferably, the substrate cleaning condition in the step S1 is ultrasonic cleaning, the ultrasonic power is 80-150W, and the ultrasonic cleaning time is 10-15 minutes.

Preferably, the purity of the copper metal target used in the step S2 is 99.99%.

Preferably, the step S2 is performed according to the following detailed steps:

s21, pre-sputtering: attaching the substrate subjected to the step S1 to a sample holder of the radio frequency magnetron sputtering equipment, then using a copper metal target as a sputtering target material, heating the substrate to 50-200 ℃, and vacuumizing the cavity of the radio frequency magnetron sputtering equipment to 5 multiplied by 10^－5～4×10^－4Pa, heating to obtain Cu with high nitrogen content and certain high temperature stability during reactive sputtering₃N film;

s22, pre-sputtering: after the cavity of the radio frequency magnetic control equipment is vacuumized to the required vacuum degree, introducing nitrogen and argon into the cavity of the radio frequency magnetic control equipment, wherein the gas flow of the nitrogen is 20-60 sccm, the gas flow of the argon is 20-60 sccm, so that the air pressure in the cavity is adjusted to 0.6-1.2 Pa, the power applied to the copper metal target is 60-200W, and pre-sputtering is carried out for 10-15 minutes. The purpose of this step is to consume the impurities and oxides on the surface of the target material and to clean the surface of the target material. Meanwhile, in the pre-sputtering process, the surface of the substrate is shielded by a baffle plate, so that the film cannot be deposited on the substrate, namely, the film layer on the substrate is not deposited at the stage;

s23, magnetron sputtering: after the pre-sputtering is carried out for 10-15 minutes in the step S22, a baffle of the radio frequency magnetron equipment is opened, the nitrogen sputtering is enabled to react with copper atoms sputtered from the copper metal target, and Cu is formed₃N molecules and depositing Cu on the substrate₃N film; after the sputtering is finished, the magnetron sputtering equipment is closed, and the Cu is taken out₃And (6) N thin films.

Preferably, the purity of the nitrogen and the argon used in the step S22 is greater than 99.999%.

Preferably, the magnetron sputtering time in the step S23 is 5-10 minutes, and the obtained Cu₃The thickness of the N film is 30-50 nm.

Preferably, the step S3 is performed according to the following detailed steps:

s31, preparation: weighing quantitative iodine simple substance, placing the iodine simple substance on the inner bottom surface of a sealed glass ware, and then placing Cu in the step S2₃The N film is attached to the upper end of the interior of the glassware to form a Cu₃Cu of N film₃The N face faces to the inner bottom surface of the glass vessel;

s32, iodination: will contain iodine and Cu₃Heating the glass bottle with N film in a thermostat to sublimate iodine to form gas-phase iodine, and exposing the Cu in the gas-phase iodine₃The N film and iodine molecules are subjected to iodination reaction to be converted into a transparent CuI conductive film. Thus, a CuI film is prepared; the quantitative determination means that the iodine is gasified and then reacts with Cu₃And forming the CuI film with the preset thickness after the N reaction.

Preferably, the time of the iodination in the step S32 is 20 to 60 minutes, and the thickness of the obtained CuI film is 90 to 150 nm.

Preferably, the temperature of the incubator is 37 ℃.

Preferably, the purity of the iodine is more than 99.8%.

Compared with the prior art, its beneficial effect lies in:

1. the preparation method of the high-transparency p-type cuprous iodide conductive film provided by the invention comprises the steps of firstly forming Cu through magnetron sputtering₃N film precursor, then passing through gas phase iodine simple substance and Cu₃The N film is subjected to iodination reaction to prepare the transparent CuI conductive film, so that the volume expansion multiple of the cuprous iodide film is reduced to about 3 times from 5-9 times, the volume expansion multiple of the cuprous iodide film is effectively reduced, the transparency, the conductivity and the thickness controllability of the cuprous iodide film are improved, the transmittance of the cuprous iodide film in a visible light wave band exceeds 80%, and the resistivity is as low as 2.41 multiplied by 10^－2Omega cm; the preparation method disclosed by the invention is adopted to prepare the high-transparency p-type cuprous iodide conductive film, and the p-type cuprous iodide conductive film does not need to be in direct contact with solid or liquid iodine, so that the surface cleanliness of the film is effectively ensured, the surface iodine residue is reduced, and the preparation method is simple in process, simple to operate and low in cost; the film quality is not limited by the contact area, the repeatability is better, and the method is more suitable for preparing large-area CuI films and carrying out batch production;

2. the preparation method of the high-transparency p-type cuprous iodide conductive film provided by the invention has low preparation temperature, and can be applied to a flexible plastic substrateThe flexible transparent conductive CuI film prepared on the PET substrate has the transmittance in a visible light region of more than 76 percent and the resistivity as low as 4.45 multiplied by 10^－2Omega cm, and stable electrical properties when bent under tensile (compressive) stress.

Drawings

FIG. 1 is a process diagram of gas-phase iodination employed in example 1 of the present invention.

FIG. 2 is Cu prepared for magnetron reactive sputtering₃The X-ray diffraction (XRD) patterns of the N film and the CuI film prepared by the method of FIG. 1 show that Cu prepared in the preparation process can be seen in FIG. 2₃N and CuI respectively accord with respective standard peak data, which proves that Cu is respectively prepared in the process₃N and CuI.

FIG. 3 shows Cu prepared by magnetron reactive sputtering₃Scanning Electron Microscope (SEM) images of the surface of the N film and the CuI film prepared by the method shown in the attached figure 1.

FIG. 4 is a visible light transmission spectrum of the CuI film of example 1 on a glass substrate and of example 2 on a PET substrate.

In the figure, 1, a glass bottle; 2. a glass substrate; 3. heating wires; 4. iodine simple substance; 5. cu₃N film; 6. a CuI film.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention and are not intended to limit the scope of the invention.

Example 1: the organic solvents used in this example, absolute ethanol and acetone, were commercially available and conventional products. The purities of copper metal target, nitrogen and argon used for the reactive magnetron sputtering are 99.99%, 99.999% and 99.999% respectively. The iodine used for iodination had a purity of 99.8%.

As shown in fig. 1 to 4, the present invention provides a method for preparing a highly transparent p-type cuprous iodide conductive film, which comprises the following steps:

s1, substrate cleaning: cleaning a glass substrate (with the size of 2cm multiplied by 3cm) by using acetone, absolute ethyl alcohol and deionized water in sequence under the conditions that the ultrasonic power is 90W and the ultrasonic cleaning time of each cleaning solution is 10 minutes, and then blowing the glass substrate by using nitrogen for standby;

s2, preparing a precursor film according to the following detailed steps:

s21, sputtering preparation: attaching the substrate subjected to the step S1 to a sample holder of a radio frequency magnetron sputtering device, then using a copper metal target as a sputtering target material, heating the substrate to 50 ℃, and vacuumizing the cavity of the radio frequency magnetron sputtering device to 4 multiplied by 10^－4Pa；

S22, pre-sputtering: vacuumizing to 4 x 10 in the cavity of the radio frequency magnetic control equipment^－4And when Pa, introducing nitrogen and argon into the cavity of the radio frequency magnetic control equipment, wherein the gas flow of the nitrogen and the argon is respectively 40sccm and 20sccm, and the gas flow ratio reaches 2: 1, adjusting the air pressure in the cavity to 0.8Pa, applying power of 120W on the copper metal target, and carrying out pre-sputtering for 15 minutes;

s23, magnetron sputtering: after the pre-sputtering of the step S22 is performed for 15 minutes, the baffle of the radio frequency magnetron equipment is opened, and nitrogen reacts with copper atoms sputtered from the copper metal target to form Cu₃N molecules, controlling the magnetron sputtering time to be 6 minutes, and depositing and forming Cu with the thickness of 40nm on the substrate₃N film; after the sputtering is finished, the magnetron sputtering equipment is closed, and the Cu is taken out₃And (6) N thin films.

S3, preparing a CuI film, specifically comprising the following detailed steps:

s31, preparation: weighing 3g of solid granular iodine simple substance by using an electronic balance, placing the iodine simple substance on the inner bottom surface of the glass bottle, namely spreading the granular iodine simple substance on the bottom of the glass bottle, and then placing the Cu in the step S2₃The N film is attached to the upper end of the inside of the glass bottle to ensure that Cu is contained₃Cu of N film₃The N surface faces the inner bottom surface of the glass bottle, as shown in the attached drawing 1, in the embodiment, the glass bottle is a sealed glass ware, and of course, the glass ware can be made into other shapes;

s32, iodination: will contain iodine and Cu₃Heating the glass bottle of N film in a thermostat at 37 deg.C to make itElemental iodine sublimes to form vapor phase iodine, and the Cu exposed in the vapor phase iodine₃And carrying out iodination reaction on the N film and iodine molecules to convert the N film into a transparent CuI conductive film, and taking out the transparent CuI conductive film after heat preservation for 60 minutes. Thus, a p-type transparent conductive CuI film is prepared on the glass substrate; the quantitative determination means that the iodine is gasified and then reacts with Cu₃And forming the CuI film with the preset thickness after the N reaction.

In the embodiment, Cu is prepared by a radio frequency magnetic control device₃And carrying out gas-phase iodination on the N film precursor in a constant temperature chamber to obtain the high-transparency P-type cuprous iodide conductive film. The thickness of the CuI film prepared on the glass substrate is 120nm, as shown in figure 4, the average transmittance of cuprous iodide in visible light region prepared by using the glass substrate as the base is more than 80%, and the resistivity is 2.3 × 10^－2Omega cm. Compared with the existing preparation method by an iodination method, the preparation method has the advantages that high transparency and conductivity are ensured; the film volume expansion multiple of the film is only 3 times, and the controllability of the film thickness is stronger. The non-contact iodination ensures the cleanliness of the film; the film quality is not limited by the contact area, and large-area films can be prepared and mass production can be realized.

Example 2: this example is substantially the same as example 1 except that the base used in this example was a flexible PET plastic substrate (size: 2cm × 3cm), the organic cleaning agent used in step S1 was absolute ethanol, and the flexible PET plastic substrate was sequentially cleaned with absolute ethanol and deionized water, each cleaning solution being ultrasonically cleaned for 15 minutes.

The magnetron sputtering time in the step S23 is 6 minutes, and the prepared Cu₃The N film has a thickness of 40nm, the iodination time in step S32 is 60 minutes, the CuI film prepared on the flexible PET substrate has a thickness of 120nm, as shown in FIG. 4, the CuI film grown on the flexible PET substrate also has a high visible light band transmittance, an average visible light band transmittance of more than 76%, and a resistivity of 4.45 × 10^－2Omega cm, and stable electrical properties when bent under tensile (compressive) stress.

By combining the experimental results, the preparation of the high-transparency CuI electric conduction material can be realized by the inventionThe film can be used for preparing flexible transparent conductive films. Both of which have a high visible region transmittance and a low specific resistance. And the preparation process is simple, the cost is low, the obtained film has good uniformity and high controllability, and as shown in figure 3, Cu₃The surface of the N film is flat and basically free of bulges, and the roughness of the surface of the iodinated cuprous iodide film is basically consistent without large difference; because the non-contact iodination is adopted, the cleanliness of the film is ensured, and the method is suitable for preparing large-area transparent conductive films and mass production. Has important significance in the fields of transparent electrodes, optoelectronic devices and flexible devices.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a high-transparency p-type cuprous iodide conductive film is characterized by comprising the following steps:

2. The method for preparing the high-transparency p-type cuprous iodide conductive film according to claim 1, wherein the method comprises the following steps: in step S1, the substrate refers to a glass substrate or a plastic substrate, and the plastic substrate is a PET (polyethylene terephthalate) film.

3. The method for preparing the high-transparency p-type cuprous iodide conductive film according to claim 1, wherein the method comprises the following steps: the cleaning agent used for cleaning the substrate in the step S1 includes an organic solvent and deionized water, wherein the organic solvent includes one or two of acetone and absolute ethyl alcohol.

4. The method for preparing the high-transparency p-type cuprous iodide conductive film according to claim 1, wherein the method comprises the following steps: the substrate cleaning condition in the step S1 is ultrasonic cleaning, the ultrasonic power is 80-150W, and the ultrasonic cleaning time is 10-15 minutes.

5. The method for preparing the high-transparency p-type cuprous iodide conductive film according to claim 1, wherein the method comprises the following steps: the purity of the copper metal target used in said step S2 was 99.99%.

6. The method for preparing the high-transparency p-type cuprous iodide conductive film according to claim 1, wherein the method comprises the following steps: the step S2 is performed according to the following detailed steps:

s21, sputtering preparation: attaching the substrate subjected to the step S1 to a sample holder of the radio frequency magnetron sputtering equipment, then using a copper metal target as a sputtering target material, heating the substrate to 50-200 ℃, and vacuumizing the cavity of the radio frequency magnetron sputtering equipment to 5 multiplied by 10^－5～4×10^－4Pa；

S22, pre-sputtering: after the cavity of the radio frequency magnetic control equipment is vacuumized to the required vacuum degree, introducing nitrogen and argon into the cavity of the radio frequency magnetic control equipment, wherein the gas flow of the nitrogen is 20-60 sccm, the gas flow of the argon is 20-60 sccm, so that the air pressure in the cavity is adjusted to 0.6-1.2 Pa, the power applied to the copper metal target is 60-200W, and pre-sputtering is carried out for 10-15 minutes;

s23, magnetron sputtering: after the pre-sputtering of the step S22 is carried out for 10-15 minutes, a baffle of the radio frequency magnetron equipment is opened, nitrogen reacts with copper atoms sputtered from the copper metal target, and Cu is formed₃N molecule, anddeposition of Cu on a substrate₃N film; after the sputtering is finished, the magnetron sputtering equipment is closed, and the Cu is taken out₃And (6) N thin films.

7. The method for preparing the high-transparency p-type cuprous iodide conductive film according to claim 6, wherein the method comprises the following steps: the purity of both the nitrogen and argon used in step S22 is greater than 99.999%.

8. The method for preparing the high-transparency p-type cuprous iodide conductive film according to claim 6, wherein the method comprises the following steps: the magnetron sputtering time in the step S23 is 5-10 minutes, and the obtained Cu₃The thickness of the N film is 30-50 nm.

9. The method for preparing the high-transparency p-type cuprous iodide conductive film according to claim 1, wherein the method comprises the following steps: the step S3 is performed according to the following detailed steps:

s31, preparation: weighing quantitative iodine simple substance, placing the iodine simple substance on the inner bottom surface of a sealed glass ware, and then placing Cu in the step S2₃The N film is adhered to the upper end of the glass ware to make Cu₃Cu of N film₃The N face faces to the inner bottom surface of the glass vessel;

s32, iodination: will contain iodine and Cu₃Heating N film glassware in a thermostat to sublimate iodine simple substance to form gas-phase iodine, and exposing the Cu in the gas-phase iodine₃The N film and iodine molecules are subjected to iodination reaction to be converted into a transparent CuI conductive film. Thus, a CuI film is prepared; the quantitative determination means that the iodine is gasified and then reacts with Cu₃And forming the CuI film with the preset thickness after the N reaction.

10. The method for preparing the high-transparency p-type cuprous iodide conductive film according to claim 1, wherein the method comprises the following steps: in the step S32, the iodination reaction time is 20-60 minutes, and the thickness of the obtained CuI film is 90-150 nm; the temperature of the constant temperature box is 37 ℃, and the purity of the iodine elementary substance is more than 99.8%.