阅读说明：本技术 一种组分可调无机钙钛矿光电薄膜及其低温制备方法和器件应用 (Component-adjustable inorganic perovskite photoelectric film, low-temperature preparation method thereof and device application ) 是由 赵传熙 麦文杰 岑国标 赵志娟 于 2019-10-16 设计创作，主要内容包括：本发明属于新型半导体材料制备及器件技术领域,具体公开了一种组分可调无机钙钛矿薄膜及其低温制备方法和器件应用。步骤如下：将CsX以及AB溶于有机溶剂中,搅拌均匀得到前驱体溶液；将所得前驱体旋涂在导电基底上；再将制膜进行退火处理,随后将样品转至原子沉积系统进行离子交换反应,得到组分精准可调的无机钙钛矿光电薄膜,并成功应用于光伏器件中。本发明方法解决了传统溶解度低问题,提高了薄膜均匀性致密性,且采用原子层沉积温度远低于200℃,不仅适用于硬质基底也适用于柔性基底,更利于实现无机钙钛矿卤族元素配比精准调控；此外前驱体均为无机物,解决了薄膜导电性差的问题,对无机钙钛矿薄膜制备及器件应用有重要意义。(The invention belongs to the technical field of novel semiconductor material preparation and devices, and particularly discloses a component-adjustable inorganic perovskite thin film, a low-temperature preparation method thereof and application of the device. The method comprises the following steps: CsX and AB are dissolved in an organic solvent, and a precursor solution is obtained after uniform stirring; spin coating the precursor on a conductive substrate; and then annealing the prepared membrane, transferring the sample to an atomic deposition system for ion exchange reaction to obtain the inorganic perovskite photoelectric film with accurate and adjustable components, and successfully applying the inorganic perovskite photoelectric film to a photovoltaic device. The method solves the problem of low solubility in the prior art, improves the uniformity and compactness of the film, adopts the atomic layer deposition temperature which is far lower than 200 ℃, is suitable for both a hard substrate and a flexible substrate, and is more beneficial to realizing the accurate regulation and control of the proportion of halogen elements of inorganic perovskite; in addition, the precursors are all inorganic substances, so that the problem of poor conductivity of the film is solved, and the method has important significance for preparation of inorganic perovskite films and application of devices.)

1. A preparation method of a component-adjustable inorganic perovskite photoelectric film is characterized by comprising the following specific steps:

(1) CsX and AB are dissolved in an organic solvent and are uniformly stirred to obtain a precursor solution;

(2) spin-coating the precursor solution obtained in the step (1) on a transparent conductive substrate to form a film;

(3) annealing the film prepared in the step (2), transferring the obtained sample to a reaction cavity of an atomic deposition system, and blowing TiCl on the surface of the film₄Carrying out chloride ion exchange reaction to prepare an inorganic perovskite photoelectric film;

wherein CsX is at least one of cesium iodide and cesium bromide in step (1); AB is PbX₂，BiX₃And SnX₂X ═ I or Br.

2. The method for preparing the composition-tunable inorganic perovskite photoelectric thin film according to claim 1, characterized in that:

the mol volume ratio of the CsX and the AB to the organic solvent in the step (1) is 0.1-0.6 mmol: 0.1-0.6 mmol: 1 mL.

3. The method for preparing the composition-tunable inorganic perovskite photoelectric thin film according to claim 1, characterized in that:

the mol volume ratio of the CsX and the AB to the organic solvent in the step (1) is 0.4 mmol: 0.4 mmol: 1 mL;

the organic solvent in the step (1) is at least one of dimethyl sulfoxide and N, N-dimethylformamide.

4. The method for preparing the composition-tunable inorganic perovskite photoelectric thin film according to claim 1, characterized in that:

stirring in the step (1) is carried out for 2-24 hours at the temperature of 60-80 ℃.

5. The method for preparing the composition-tunable inorganic perovskite photoelectric thin film according to claim 1, characterized in that:

the transparent conductive substrate in the step (2) is ITO or FTO;

the spin coating in the step (2) is spin coating for 5-40 s at 400-6000 rpm;

the thickness of the film in the step (2) is 50-200 nm.

6. The method for preparing the composition-tunable inorganic perovskite photoelectric thin film according to claim 1, characterized in that:

the annealing temperature in the step (3) is 80-150 ℃, and the time is 5-20 min;

and (3) controlling the pressure of the reaction cavity in the step (3) to be 7-15 Pa and the temperature to be 85-150 ℃.

7. The method for preparing the composition-tunable inorganic perovskite photoelectric thin film according to claim 1, characterized in that:

TiCl in the step (3)₄The number of the blowing circulation cycles is 1-300, in each circulation, the blowing time is 100-5000 ms, and TiCl₄The purge content of (A) is 50 to 1000ppm, N₂The cleaning time is 100ms-5 s.

8. The method for preparing the composition-tunable inorganic perovskite photoelectric thin film according to claim 1, characterized in that:

cleaning the transparent conductive substrate in the step (2) by the following method before spin coating:

sequentially carrying out ultrasonic cleaning on the transparent conductive substrate for 10-15 min by using water, acetone and isopropanol; then using N for the cleaned conductive substrate₂Blow-drying and carrying out ultraviolet-ozone clean surface treatment.

9. The inorganic perovskite photoelectric thin film with adjustable components prepared by the method according to any one of claims 1 to 8.

10. Use of the compositionally tunable inorganic perovskite photovoltaic thin film of claim 9 in the preparation of ultraviolet photodetectors, blue-violet light emitting diodes, LEDs, and inorganic perovskite solar cells.

Technical Field

The invention belongs to the technical field of controllable preparation and devices of novel semiconductor photoelectric materials, and particularly relates to a component-adjustable inorganic perovskite photoelectric film, a low-temperature preparation method thereof and application of the device.

Background

In recent years, organic/inorganic hybrid halide perovskite materials exhibit outstanding photoelectric conversion efficiency due to excellent characteristics such as high light absorption coefficient and long diffusion distance; the method is widely applied to the fields of solar cells, photoelectric detectors, light emitting diodes and the like. However, the hybrid perovskite material has poor light, thermal and humidity stability, which greatly limits the wide application in the field of photoelectricity. It is appreciated that inorganic perovskite photovoltaic materials, such as CsMX₃(M ═ Pb, Bi, Sn, X ═ Cl, Br, I)), besides the photoelectric characteristics similar to those of the hybrid perovskite, the material also has good environmental stability, is expected to replace the hybrid perovskite material, and has huge application value in the photoelectric field.

The inorganic halide perovskite material has wide chemical adjustable range and adjustable optical band gap (the range is 2.3eV-3eV), and simultaneously, the low temperature method is compatible with a flexible substrate, and the like, and shows application potential in the fields of LED illumination, photoelectric detection and the like. Such as Georgian Nedelcu et al [ Nano Lett.2015,15, 565635-]Report a chemical solution method to achieve lead-based perovskite (CsPbX)₃(X ═ Cl, Br, I)) halogen elements in the quantum dots are subjected to rapid halogen ion exchange and continuous component regulation, so that wide-range regulation of band gaps is realized; wuhan university Square national professor team reports the use of chemical dispensing processes in combination with antisolvent vapor space limitations of Si/SiO₂Growth of highly crystalline CsPbCl on substrates₃Nanosheets and successful reports of near ultraviolet detectors [ Small2019,1902618-1902626]. Gong et al, university of Kansas, USA, reported colloidal synthesis of CsPbCl₃Quantum dot and surface modification method based on thiol group for improving charge transfer efficiency and material stability [ ACS Nano 2019,13, 1772-1783-]. However, patent and literature research reports of researchers in the early days on chloride perovskite materials still focus on the morphology of quantum dots or micro-region single crystals, which is still a great challenge for thin film type integrated devices. At present, CsPbCl has not been provided₃The preparation of the perovskite uniform compact film and the photoelectric device thereof. This challenge is due to two main reasons: (1) The traditional solution method preparation firstly faces the problem of low solubility, namely CsCl and PbCl₂Very insoluble in dimethyl sulfoxide (DMSO) or in N, N-Dimethylformamide (DMF), only by relatively complex chemical methods; (2) the chemical methods reported in the literature often involve complex surface interface modifications, such as chemical long-chain functional groups like ODE, OA, OLA, etc., which on the one hand cause chemical instability of halide perovskite surface and on the other hand cause the surface of the perovskite to present an insulating layer, reducing CsPbCl_xBr_3-xThe conductivity of perovskite causes the electrical characteristics of the device to be reduced, and the application of perovskite in the field of electronic devices is severely limited.

Disclosure of Invention

In order to solve the problem of CsPbCl at present_xBr_3-xThe problems of low solubility, poor photoelectric properties and the like existing in the preparation process of the perovskite film, namely the raw materials CsCl and PbCl₂The perovskite material is very difficult to dissolve in DMSO or DMF solvent and a large number of functional groups are introduced in the preparation process, so that the conductivity of the perovskite material is reduced. The invention aims to provide a preparation method of a component-adjustable inorganic perovskite photoelectric film.

The invention also aims to provide the inorganic perovskite photoelectric thin film with adjustable components prepared by the method.

The invention further aims to provide application of the inorganic perovskite photoelectric thin film with adjustable components in preparation of ultraviolet photoelectric detectors, blue-violet Light Emitting Diodes (LEDs) and inorganic perovskite solar cells.

The purpose of the invention is realized by the following scheme:

a preparation method of a component-adjustable inorganic perovskite photoelectric film comprises the following specific steps:

(1) CsX and AB are dissolved in an organic solvent and are uniformly stirred to obtain a precursor solution;

(2) spin-coating the precursor solution obtained in the step (1) on a transparent conductive substrate to form a film;

(3) annealing the film prepared in the step (2), transferring the obtained sample to a reaction cavity of an atomic deposition system, and blowing TiCl on the surface of the film₄To carry out a chloride ion exchange reaction to obtainAn organic perovskite photoelectric thin film;

wherein CsX is at least one of cesium iodide and cesium bromide in step (1); AB is PbX₂，BiX₃And SnX₂X ═ I or Br.

The mol volume ratio of the CsX and the AB to the organic solvent in the step (1) is 0.1-0.6 mmol: 0.1-0.6 mmol: 1 mL. Preferably 0.4 mmol: 0.4 mmol: 1 mL.

The organic solvent in the step (1) is at least one of dimethyl sulfoxide and N, N-dimethylformamide.

Stirring for 2-24 h at 60-80 ℃ in the step (1); preferably, stirring is carried out at 70 ℃ for 12 h.

And (3) the transparent conductive substrate in the step (2) is ITO or FTO.

The transparent conductive substrate in the step (2) is preferably cleaned by the following method before spin coating:

sequentially carrying out ultrasonic cleaning on the transparent conductive substrate for 10-15 min by using water, acetone and isopropanol; then using N for the cleaned conductive substrate₂Drying and carrying out ultraviolet-Ozone (UV-Ozone) clean surface treatment; the time of the ultraviolet-ozone clean surface treatment is preferably 20 min.

The thickness of the film in the step (2) is 50-200 nm;

the spin coating in the step (2) is spin coating for 5-40 s at 400-6000 rpm; preferably, the spin coating is performed for 5-10 s at 400-800 rpm, and then for 20-40 s at 3000-6000 rpm; more preferably, the spin coating is spin coating at 500rpm for 6s, followed by spin coating at 5000rpm for 30 s.

The annealing temperature in the step (3) is 80-150 ℃, and the time is 5-20 min; preferably, the annealing temperature is 100 ℃ and the annealing time is 10 min.

The sample in the step (3) is Cs₃Bi₂X₉、CsSnX₃And CsPbX₃Wherein X ═ Cl, Br, I.

The pressure of the reaction cavity in the step (3) is 7-15 Pa, and the temperature is 85-150 ℃; preferably, the pressure of the reaction chamber is 9Pa and the temperature is 105 ℃.

TiCl in the step (3)₄The number of the blowing circulation cycles is 1-300, in each circulation, the blowing time is 100-5000 ms, and TiCl₄The purge content of (A) is 50 to 1000ppm, N₂The cleaning time is 100ms-5 s. Preferably, the TiCl₄The number of the blowing cycles is 1 to 50, the blowing time is 2 to 4s in each cycle, and TiCl₄Purge content of 200ppm, N₂The washing time was 2 s.

The inorganic perovskite photoelectric thin film with adjustable components is obtained according to the method.

The inorganic perovskite photoelectric film with adjustable components is applied to the preparation of ultraviolet photoelectric detectors, blue-violet Light Emitting Diodes (LEDs) and inorganic perovskite solar cells.

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

(1) solves the problem of low solubility in the prior art, and improves the uniformity and compactness of the film

CsCl and PbCl due to synthetic material₂The method is difficult to dissolve in DMSO or DMF solvent, so that the synthesized film in the traditional one-step spin-coating method is sparse, and a compact and uniform film is difficult to obtain.

(2) All-inorganic thin film and excellent in electrical characteristics

In order to improve the electrical properties and stability of the perovskite thin film, the perovskite thin film prepared by the conventional method is subjected to surface modification through organic molecules, a large number of organic functional groups are remained on the surface of the perovskite to form an insulating layer, and the perovskite thin film is not beneficial to the transfer of electrons on the surface interface of the perovskite. The precursor of the method is inorganic matter, and the problem of poor conductivity of the film can be solved.

(3) Low temperature preparation and high flexible base compatibility

The temperature of the cavity of the atomic layer deposition technology is far lower than 200 ℃, so that the method is not only suitable for hard substrates but also suitable for flexible substrates (such as PET/ITO and PET/FTO), and the material prepared by the method is suitable for flexible electronic devices due to the low-temperature process (105 ℃) of material preparation.

(4) The halogen proportion is accurate and adjustable, and the optical band gap is adjustable

According to the traditional method, the proportion of halogen elements is regulated and controlled by changing the proportion of raw materials in a precursor, the method is low in efficiency and low in halogen proportion regulation precision, atomic layer deposition is adopted to assist halogen ion exchange, the method is more beneficial to realizing the precise regulation and control of the proportion of the perovskite halogen elements, and the optical band gap width, the fluorescence spectrum emission peak position and the crystal structure of the inorganic perovskite are gradually regulated and controlled. The ultraviolet photoelectric detector has obvious light modulation characteristics and ultraviolet region response.

Drawings

FIG. 1 is a schematic diagram of perovskite synthesis by atomic layer deposition assisted halogen ion exchange.

Fig. 2 is a 0.4M cesium lead bromide (a) and 0.1M cesium lead chloride (b) precursor solution of comparative example 1.

FIG. 3 is an XPS plot of inorganic perovskite thin films prepared at different cycle numbers for example 1, where (a) is Cl and (b) is Br.

FIG. 4 is an absorption spectrum of the inorganic perovskite thin film prepared in example 1 at different cycle numbers.

FIG. 5 is a steady state fluorescence spectrum of inorganic perovskite thin films prepared under different cycle numbers in example 1.

FIG. 6 is an XRD pattern of inorganic perovskite thin films prepared under different cycle numbers in example 1.

FIG. 7 is an I-T curve of the near-UV photodetector of example 3.

Fig. 8 is a spectral response curve of the near-ultraviolet photodetector of example 3.

FIG. 9 is a schematic diagram of the preparation of inorganic perovskite photoelectric thin film by the low-temperature gas-phase ion exchange method of the present invention.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.