CN105470397A - Preparation method of organic and inorganic hybrid perovskite film possessing high moisture stability and photoelectric conversion efficiency - Google Patents

Abstract

The invention relates to a preparation method of an organic and inorganic hybrid perovskite film possessing high moisture stability and photoelectric conversion efficiency. The method is characterized by processing a CH3NH3PbI3 material surface; replacing hydrophilic methylamine cations of the surface; and self-assembling ammonium ions possessing a hydrophobic structure so as to form a layer of monomolecular film so that sensitivity of a perovskite material to water is greatly reduced. The perovskite material possessing a waterproof structure has a very important meaning to perovskite material processing and preparation under an atmospheric environment.

Description

A preparation method of an organic-inorganic hybrid perovskite film with high moisture stability and photoelectric conversion efficiency

technical field

The invention relates to a method for preparing an organic-inorganic hybrid perovskite film with high photoelectric conversion efficiency and moisture stability. The method has important applications in the field of preparation and processing of new solar cells.

Background technique

Energy shortage and environmental pollution are two major problems that human beings urgently need to solve. On the one hand, we need to save energy, reduce energy consumption, and use renewable clean energy as much as possible; on the other hand, we must reduce pollutant emissions and eliminate environmental pollution. Sunlight is clean energy, how to convert sunlight into energy that is convenient for us to use and how to use sunlight to eliminate environmental pollution has become a research hotspot. Semiconductor functional materials have unique advantages in absorbing and utilizing sunlight. For example, organic-inorganic hybrid perovskite solar cells convert sunlight into electricity that is convenient for us to use.

Perovskite solar cells usually have a sandwich structure, specifically conductive glass/titanium dioxide dense film/perovskite/hole transport layer/back electrode, in which the organic-inorganic hybrid perovskite film is its key component, bearing the load It plays an important role in the generation, separation and transmission of flow particles. At present, the laboratory efficiency of perovskite solar cells has exceeded 20%, which has reached the commercial threshold, but its stability (especially in a humid environment) is a key issue that limits its further development. In response to these problems, D. McGehee et al. reported the use of a 2D perovskite structure with a photoelectric conversion efficiency of 4.73% (Angew. Chem. Int. Ed. 2014, 126, 11414-11417). X.Tao et al have reported a CH ₃ NH ₃ Pb(SCN) ₂ I structure with certain moisture tolerance. Although the stability has been improved, the device efficiency can only reach 8% (Angew.Chem.Int.Ed .2015, 127, 7729-7730). The absolute efficiency of these new perovskite materials is far below 20%, which cannot meet the needs of practical production.

In this application, we use hydrophobic ammonium iodide isopropanol solution to treat perovskite film, react at room temperature for 5-600s, and then wash with pure isopropanol solution to obtain perovskite film with monomolecular layer modification on the surface. The prepared film maintains excellent photoelectric response, and its photoelectric conversion efficiency can exceed 15%. At the same time, the stability of its perovskite structure is greatly improved, and it can be stored for more than 30 days at 90% relative humidity.

Contents of the invention

In view of the above problems, the present invention provides a method for preparing an organic-inorganic hybrid perovskite film with high photoelectric conversion efficiency and moisture stability. The specific technical scheme is as follows:

A method for preparing an organic-inorganic hybrid perovskite film with high moisture stability and photoelectric conversion efficiency, comprising the following steps:

First, treat the perovskite film with 5-40mM ammonium iodide in isopropanol solution, and react at 15-50°C for 5-600s; usually, 5-20mL of the above reaction solution is required for every 1g of perovskite;

Then, it was cleaned with pure isopropanol solution to obtain a perovskite film with a monomolecular layer modification on the surface;

Finally, after the perovskite solar cells were assembled using standard processes, the photoelectric conversion efficiency was tested.

The perovskite film is a CH ₃ NH ₃ PbI ₃ or NH ₂ CHNH ₂ PbI ₃ film with a thickness of 400-600 nm.

The ammonium iodide has a hydrophobic structure and is selected from tetramethylammonium iodide, tetraethylammonium iodide, tetrabutylammonium iodide, tetrapentylammonium iodide and cetyltrimethylammonium iodide.

The surface morphology of the perovskite film has slight changes before and after treatment, the surface roughness increases, and a waterproof monomolecular film is formed on the surface. The thickness is related to the molecular size of the ammonia molecule used, usually one molecular layer. thickness.

Compared with the existing perovskite film method, the present invention has the following advantages: simple preparation process, good stability in humid environment, and high photoelectric conversion efficiency.

Description of drawings

Fig. 1 is the ultraviolet-visible spectrogram before and after the treatment of embodiment 5;

Fig. 2 is the volt-ampere characteristic curve figure of embodiment 5;

Fig. 3 is the change schematic diagram of the water contact angle before and after the treatment of Example 5; Standard is the contact angle photo of the sample before treatment, and TEAI is the contact angle photo of the sample after treatment with TEAI;

Fig. 4 is the scanning electron microscope picture after embodiment 5 processing;

FIG. 5 is an XRD pattern of the perovskite material before and after treatment in Example 5 after being stored at 90% relative humidity for 30 days.

detailed description

Below, the content of the present invention is further described with examples, but the protection scope of the present invention is not limited to examples. Other changes and modifications made by those skilled in the art without departing from the spirit and protection scope of the present invention are still included in the protection scope of the present invention.

Example 1

The perovskite film was treated with 40 mM tetramethylammonium iodide isopropanol solution, reacted at room temperature for 60 s, then washed with pure isopropanol solution for 3 times, and dried to obtain a perovskite film with a monomolecular layer modification on the surface. Finally, after assembling the perovskite solar cell using the standard process, the photoelectric conversion efficiency reaches 12.89% (short circuit current 21.0mA/cm ² , open circuit voltage 990mV, fill factor 0.62).

Example 2

The perovskite film was treated with 20mM tetrabutylammonium iodide isopropanol solution, reacted at room temperature for 300s, then washed with pure isopropanol solution for 3 times, and dried to obtain a perovskite film with a monomolecular layer modification on the surface. Finally, after assembling the perovskite solar cell using the standard process, the photoelectric conversion efficiency reaches 11.94% (short circuit current 19.7mA/cm ² , open circuit voltage 950mV, fill factor 0.64).

Example 3

The perovskite film was treated with 25 mM tetrapentyl ammonium iodide isopropanol solution, reacted at room temperature for 60 s, then washed with pure isopropanol solution for 3 times, and dried to obtain a perovskite film with a monomolecular layer modification on the surface. Finally, after assembling the perovskite solar cell using the standard process, the photoelectric conversion efficiency reaches 7.15% (short circuit current 12.8mA/cm ² , open circuit voltage 900mV, fill factor 0.62).

Example 4

The perovskite film was treated with 10mM tetraethylammonium iodide isopropanol solution, reacted at room temperature for 600s, then washed with pure isopropanol solution for 3 times, and dried to obtain a perovskite film with a monomolecular layer modification on the surface. Finally, after assembling the perovskite solar cell using the standard process, the photoelectric conversion efficiency reaches 13.65% (short circuit current 20.0mA/cm ² , open circuit voltage 1000mV, fill factor 0.68).

Example 5

Treat the perovskite film with 25mM tetraethylammonium iodide isopropanol solution, react at room temperature for 20s, then wash with pure isopropanol solution for 3 times, and obtain a perovskite film with monomolecular layer modification on the surface after drying. The water contact angle of the surface is significantly improved, as shown in Figure 3. The ultraviolet-visible spectra of the samples before and after treatment are shown in Figure 1, and the scanning electron microscope pictures of the samples after treatment are shown in Figure 4. The samples were stored at 90% relative humidity, and it was found that after 30 days, the overall crystal phase structure did not change much, while the comparative samples were severely decomposed. As shown in Figure 5, the perovskite material before treatment has obvious decomposition, and the decomposition peak of the treated sample is not obvious. last adopted standard

After the perovskite solar cell is assembled by the process, the photoelectric conversion efficiency reaches 15.05% (short circuit current 20.2mA/cm ² , open circuit voltage 995mV, fill factor 0.75), as shown in FIG. 2 .

The test results of Examples 1 to 4 are similar to Example 5.

Claims (4)

1. there is a preparation method for the organic-inorganic mixed type perovskite thin film of high humidity stability and electricity conversion, comprise following steps:

First, with the aqueous isopropanol process perovskite thin film of 5 ~ 40mM ammonium iodide, at 15 ~ 50 DEG C, 5 ~ 600s is answered; Wherein, the aqueous isopropanol of the corresponding described ammonium iodide of 1g perovskite is 5 ~ 20mL;

Then, clean up with pure aqueous isopropanol, obtain the perovskite thin film that surface has monolayer modification;

Finally, after adopting standard technology assembling perovskite solar cell, testing photoelectronic transformation efficiency.

2. preparation method according to claim 1, is characterized in that, described perovskite thin film is the CH of 400 ~ 600nm thickness ₃nH ₃pbI ₃or NH ₂cHNH ₂pbI ₃film.

3. preparation method according to claim 1, is characterized in that, described ammonium iodide has hydrophobic structure, is selected from tetramethyl-ammonium iodide, tetraethyl ammonium iodide, tetrabutylammonium iodide, four pentyl ammonium iodide and cetyl trimethyl ammonium iodide.

4. preparation method according to claim 1, it is characterized in that, described perovskite thin film before treatment rear surface pattern has slight change, its surface roughness increases, surface produces the monomolecular film of one deck waterproof, thickness is relevant with the molecular dimension of adopted amino molecule, is the thickness of a molecular layer.