阅读说明：本技术 一种铯锡碘薄膜的制备方法及其应用 (Preparation method and application of cesium tin iodine film ) 是由 佘利敏 谢振杨 张伟风 于 2020-12-02 设计创作，主要内容包括：本发明公开了一种铯锡碘薄膜的制备方法,属于半导体材料技术领域。包括以下步骤：S1、在真空条件下,将二碘化锡和碘化铯分别加热至440℃和210℃,并同时向基底沉积二碘化锡和碘化铯,冷却至室温,制得铯锡碘薄膜前驱体；其中,沉积的过程中,所述二碘化锡和碘化铯分别以0.5层/min的速率共沉积25～35min；所述基底温度为-33～-23℃；S2、将基底上沉积的铯锡碘薄膜前驱体在温度为100～120℃进行退火处理,即得铯锡碘薄膜。本发明提供的铯锡碘薄膜的制备方法工艺简单、薄膜质量高,特别适合用于开发高性能的无铅钙钛矿太阳能电池。(The invention discloses a preparation method of a cesium tin iodine film, and belongs to the technical field of semiconductor materials. The method comprises the following steps: s1, heating the tin diiodide and the cesium iodide to 440 ℃ and 210 ℃ respectively under a vacuum condition, simultaneously depositing the tin diiodide and the cesium iodide on a substrate, and cooling to room temperature to obtain a cesium tin iodine film precursor; in the deposition process, co-deposition is carried out on the tin diiodide and the cesium iodide for 25-35 min at the rate of 0.5 layer/min respectively; the substrate temperature is-33 to-23 ℃; s2, annealing the cesium tin iodine film precursor deposited on the substrate at the temperature of 100-120 ℃ to obtain the cesium tin iodine film. The preparation method of the cesium tin iodine film provided by the invention is simple in process and high in film quality, and is particularly suitable for developing a high-performance lead-free perovskite solar cell.)

1. The preparation method of the cesium tin iodine film is characterized by comprising the following steps of:

s1, heating the tin diiodide and the cesium iodide to 440 ℃ and 210 ℃ respectively under a vacuum condition, simultaneously depositing the tin diiodide and the cesium iodide on a substrate, and cooling to room temperature to obtain a cesium tin iodine film precursor;

in the deposition process, co-deposition is carried out on the tin diiodide and the cesium iodide for 25-35 min at the rate of 0.5 layer/min respectively; the substrate temperature is-33 to-23 ℃;

s2, annealing the cesium tin iodine film precursor deposited on the substrate at the temperature of 100-120 ℃ to obtain the cesium tin iodine film.

2. According toThe method for preparing cesium tin iodine thin film according to claim 1, wherein said vacuum is not less than 10 ≥ m^-6Pa。

3. The method of preparing cesium tin iodide thin films according to claim 1, wherein the substrate is an Au film, Au (111) single crystal or graphene-bonded SiC (0001).

4. The method for preparing the cesium tin iodine thin film according to claim 1, wherein in the annealing process, the temperature rise rate is 2.0-5 ℃/min.

5. The method for preparing cesium tin iodide thin films according to claim 4, wherein the annealing time is 30-60 min.

6. A cesium tin iodide thin film prepared by the method for preparing a cesium tin iodide thin film according to any one of claims 1 to 5.

7. Use of the cesium tin iodide thin film of claim 6 in a lead-free perovskite solar cell.

Technical Field

The invention belongs to the technical field of semiconductor materials, and particularly relates to a preparation method and application of a cesium tin iodine film.

Background

At present, a class of organic-inorganic hybrid perovskite semiconductors (AMX3, a is a cation, and is commonly Methylamine (MA), Formamidine (FA), cesium (Cs), etc., and X is Cl, I, Br, etc.) are applied to a planar heterojunction solar cell due to their excellent photoelectric properties. Two key difficulties exist in promoting the wide application of the organic-inorganic perovskite solar cell, (1) the organic-inorganic hybrid perovskite needs to be lead-free, so that the organic-inorganic hybrid perovskite is more green and environment-friendly. (2) The thermal stability of such organometallic perovskite materials having excellent photoelectric properties needs to be further improved. On the one hand, tin (Sn) and germanium (Ge) are expected to replace the cognate element lead (Pb) in such hybrid perovskites, thereby enabling such perovskite solar cells to go towards lead-free. On the other hand, the alkali metal element cesium (Cs) may be used in place of the organic group (CH) of such organometallic perovskite₃NH₃ ⁺) Achieving mineralization may improve the thermal stability of such perovskite photovoltaic materials to some extent. CsSnI₃The semiconductor is non-toxic and has a direct band gap of about 1.3eV, and the energy conversion efficiency can reach 33% theoretically.

Nonetheless, with CsSnI₃The energy conversion effect of the solar cell as the light absorbing layer is only about 3%, which is much lower than that of the lead-containing organic-inorganic hybrid perovskite solar cell. CsSnI prepared by traditional preparation method (such as two-step method and the like)₃The thin film has high density of Sn and Cs vacancy defects, so that the migration length and the service life of carriers (electrons and holes) of the thin film become shorter, and the device performance of the thin film is seriously influenced. Alternate deposition of SnI by a two-step process₂And the CsI mode easily causes that the chemical ratio of the CsSnI3 film is difficult to be precisely controlled in spatial distribution, so that a large number of Sn and Cs vacancy defects are formed.

Disclosure of Invention

The present invention is directed to a cesium tin iodide thin film, which overcomes the drawbacks and disadvantages of the above-mentioned methods

The preparation method of the film has simple process and high film quality, and is particularly suitable for developing high-performance lead-free perovskite solar cells.

The invention provides a preparation method of a cesium tin iodine film, which comprises the following steps:

s1, heating the tin diiodide and the cesium iodide to 440 ℃ and 210 ℃ respectively under a vacuum condition, simultaneously depositing the tin diiodide and the cesium iodide on a substrate, and cooling to room temperature to obtain a cesium tin iodine film precursor;

in the deposition process, co-deposition is carried out on the tin diiodide and the cesium iodide for 25-35 min at the rate of 0.5 layer/min respectively; the substrate temperature is-33 to-23 ℃;

s2, annealing the cesium tin iodide thin film precursor deposited on the substrate at the temperature of 100-120 ℃ to obtain cesium tin iodide (CsSnI)₃) A film.

Preferably, the vacuum is 10 or more^-6Pa。

Preferably, the substrate is an Au film, an Au (111) single crystal, or a graphene-bonded SiC (0001).

Preferably, in the annealing process, the heating rate is 2.0-5 ℃/min.

More preferably, the annealing time is 30-60 min.

The second purpose of the invention is to provide a cesium tin iodine film.

The third purpose of the invention is to provide the application of the cesium tin iodine thin film in a lead-free perovskite solar cell.

Compared with the prior art, the invention has the following beneficial effects:

the CsSnI provided by the invention₃A process for preparing the film includes such steps as putting tin diiodide and cesium iodide in quartz crucible, depositing Pb iodide and cesium iodide on smooth substrate (Au (111) substrate) in high-vacuum environment, and codepositing at-33-23 deg.C while easily adsorbing iodine on substrate₂The chemical equivalent reaction can be better generated, the prepared sample is annealed to the room temperature in the room temperature environment, and then the prepared sample is annealed in high vacuum, so that the sample with the chemical equivalent reaction function can be obtainedA cesium tin iodine perovskite thin film with atomic-level flatness; the method has simple process and high film quality, and is particularly suitable for developing lead-free perovskite solar cells with high performance.

The CsSnI provided by the invention₃Compared with the traditional Pb perovskite material, the film material has the advantages of no toxicity, environmental protection, no pollution, low price and the like.

Drawings

FIG. 1 CsSnI in example 1₃Scanning Tunneling Microscope (STM) of thin films.

FIG. 2 CsSnI in example 1₃Atom resolved images of the film.

FIG. 3 CsSnI in comparative example 1₃Scanning Tunneling Microscope (STM) of thin films.

FIG. 4 CsSnI in comparative example 2₃Scanning Tunneling Microscope (STM) of thin films.

Detailed Description

In order to make the technical solutions of the present invention better understood and implemented by those skilled in the art, the present invention is further described below with reference to the following specific embodiments and the accompanying drawings, but the embodiments are not meant to limit the present invention.

It should be noted that the reagents and materials used in the following examples are commercially available unless otherwise specified; wherein, the purity of the tin diiodide and the cesium iodide is 99.999 percent; the experimental methods are all conventional methods unless otherwise specified.

Example 1

A preparation method of a cesium tin iodine film comprises the following steps:

respectively placing tin diiodide and cesium iodide in quartz crucibles, respectively heating and degassing in ultrahigh vacuum environment, and maintaining vacuum of vacuum chamber at 10 or above^-6Pa; simultaneously, blowing a certain amount of liquid nitrogen into a cooling pipe of the sample stage, and reducing the temperature of the Au (111) substrate to-28 ℃; heating the evaporation source of tin diiodide and cesium iodide to 440 ℃ and 210 ℃, and depositing the tin diiodide and the cesium iodide on the Au (111) substrate together, wherein CsI and SnI are enabled to be in the process of deposition₂Can better generateCarrying out a chemical equivalent reaction; wherein, in the deposition process, the tin diiodide and the cesium iodide are co-deposited for 30min at the rate of 0.5 layer/min respectively;

heating the precursor of the cesium tin iodine thin film deposited on the substrate to 120 ℃ at the speed of 3.5 ℃/min and annealing for 45min to obtain the cesium tin iodine perovskite thin film (CsSnI) with high quality and atomic-level flatness₃A film).

Example 2

The same as example 1, except that: controlling the temperature of an Au (111) substrate at-23 ℃; the annealing time was 30 min.

Example 3

The same as example 1, except that: the temperature of the Au (111) substrate is controlled at-33 ℃, and the annealing time is 60 min.

Comparative example 1

The same as example 1, except that: the temperature of the Au (111) substrate was controlled at 24 ℃.

Comparative example 2

The same as example 1, except that: the temperature of the Au (111) substrate was controlled at 47 ℃.

To illustrate the relevant performance of the cesium tin iodide thin film obtained by the preparation method of the cesium tin iodide thin film provided by the invention, similar to the cesium tin iodide thin films prepared in examples 1 to 3, only the cesium tin iodide thin film (CsSnI) prepared in example 1 is used₃Film) of the film, see fig. 1-2, while comparative examples 1-2 were used as control groups, see fig. 3-4.

FIG. 1 CsSnI in example 1₃Scanning Tunneling Microscope (STM) photographs of the film show that the surface of the film is very flat and has very regular edges and angles, and the prepared sample has very good crystallization quality.

FIG. 2 CsSnI in example 1₃Atom resolution images of the films indicate that the prepared films have high quality crystal structures.

FIG. 3 CsSnI in comparative example 1₃Scanning Tunneling Microscopy (STM) of the thin film, large and partially irregular clusters (cluster) appeared on the thin film, and the crystalline quality of the thin film was inferior to that of example 1.

FIG. 4 CsSnI in comparative example 2₃Scanning Tunneling Microscope (STM) of the thin film, many irregular clusters (cluster) appeared on the thin film, and the crystalline quality of the thin film was further deteriorated.

In conclusion, the CsSnI provided by the invention₃A process for preparing the film includes such steps as putting tin diiodide and cesium iodide in quartz crucible, depositing Pb iodide and cesium iodide on smooth substrate (Au (111) substrate) in high-vacuum environment, and codepositing at-33-23 deg.C while easily adsorbing iodine on substrate₂The method has the advantages that chemical equivalent reaction can be better carried out, the prepared sample is annealed to room temperature in a room temperature environment, and then the prepared sample is annealed in high vacuum, so that the cesium tin iodoperovskite thin film with atomic level flatness can be obtained; the method has simple process and high film quality, and is particularly suitable for developing lead-free perovskite solar cells with high performance.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, it is intended that such changes and modifications be included within the scope of the appended claims and their equivalents.