CN107887515B

CN107887515B - A kind of mesoporous perovskite film and its preparation method and application

Info

Publication number: CN107887515B
Application number: CN201711203572.XA
Authority: CN
Inventors: 胡子阳; 诸跃进; 孙凯; 沈百慧; 路春艳
Original assignee: Ningbo University
Current assignee: Ningbo University
Priority date: 2017-11-27
Filing date: 2017-11-27
Publication date: 2021-04-27
Anticipated expiration: 2037-11-27
Also published as: CN107887515A

Abstract

The invention relates to a mesoporous _perovskite film, a preparation method and application thereof, and belongs to the technical field of optoelectronic devices based _on the _perovskite film. I. The thickness of the mesoporous structure perovskite film prepared by the present invention ranges from 400-6000 nm. Compared with the traditional experimental method, the mesoporous structure perovskite film prepared by this method does not have a large amount of PbX ₂ residue, and the heating time Effectively shortening; the mesoporous perovskite film prepared by this method has effectively enhanced light absorption ability and effectively improved electron transport ability, which provides a new idea and method for the preparation of high-performance perovskite optoelectronic devices.

Description

Mesoporous perovskite film and preparation method and application thereof

Technical Field

The invention belongs to the technical field of photoelectric devices based on perovskite thin films, and particularly relates to a mesoporous perovskite thin film and a preparation method and application thereof.

Background

Organic-inorganic hybrid metal halide perovskite CH₃NH₃PbX₃The (X ═ Cl, Br and I) has the characteristics of narrow band gap, high molar extinction coefficient, high carrier mobility and the like, and the photoelectric device made of the material with the structure is called a perovskite photoelectric device. The preparation of perovskite materials becomes the subject of research of the majority of researchers due to the characteristics of low cost and simple preparation process. Perovskite solar cells as representative photoelectric devices have been rapidly developed in recent years, the current photoelectric conversion efficiency reaches 22%, and the development speed is far faster than that of other solar cells.

The perovskite optoelectronic device comprises an optoelectronic layer composed of a perovskite material, which is an organometallic halide light absorbing material having the perovskite crystal form (ABX 3). In this perovskite ABX₃In the structure, A is methylamino (CH)₃NH₃) B is metallic lead atom, and X is halogen atom such as chlorine, bromine, iodine, etc. In current scientific research, the most commonly used material is ammonium lead methyl iodide (CH)₃NH₃PbI₃) It has excellent photoelectric properties: high extinction coefficient, long carrier lifetime and adjustable forbidden band width. The perovskite thin film with the wavelength of hundreds of nanometers can fully absorb sunlight with the wavelength of below 800 nm. In addition, such a material is easy to prepare, and is generally prepared by a solution method, a steam method, or the like. The most common method is to synthesize the perovskite thin film by using a solution one-step method and a two-step method and then annealing, and the perovskite thin film prepared by the traditional process is compact and has a polycrystalline structure and high surface flatness. The invention provides a preparation method of a polycrystalline granular mesoporous perovskite thin film, which has different electrical and optical properties from the traditional compact perovskite polycrystalline thin film. The mesoporous perovskite thin film has a light trapping effect obviously superior to that of a planar structure, but the carrier conduction performance of the mesoporous perovskite thin film is almost the same as that of the planar structure. The novel mesoporous perovskite is different from the reported rod-shaped or plane-shaped perovskite morphology, and shows better performance in perovskite-based photoelectric devices.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a mesoporous perovskite thin film which is reasonable in structural design and has higher photovoltaic performance application, and a preparation method and application thereof.

The technical scheme adopted by the invention for solving the problems is as follows: a mesoporous perovskite thin film is characterized in that: is of a mesoporous structure.

The chemical formula of the invention is CH₃NH₃PbX₃And X is Cl, Br or I.

A preparation method of a mesoporous perovskite film is characterized by comprising the following steps: the method comprises the following steps:

dissolving inorganic halide in an organic solvent, heating and stirring until the inorganic halide is completely dissolved to form an inorganic halide precursor solution;

secondly, the inorganic halide precursor solution obtained in the step one is deposited on a substrate through spin coating or blade coating to form an inorganic halide layer, then the organic solution of volatile Lewis base is used for carrying out steam treatment on the inorganic halide layer by layer in a closed container for a period of time, and the generated path is easyForming an addition product of an inorganic halide layer and a Lewis base by a Lewis acid-base addition reaction, and then heating and drying the addition product to remove the excessive or partial Lewis base from the organic solvent molecules to form porous PbX₂A network structure, wherein mesopores are formed in the adduct, and then the adduct is annealed for a period of time and cooled to room temperature; to this end, the inorganic halide layer treatment is completed; in the step, the annealing time is 10-20min, and the heating temperature is 70-80 ℃;

dissolving organic halide in isopropanol to form isopropanol solution of organic halide;

fourthly, using isopropanol solution of organic halide to treat the inorganic halide layer after the treatment in the second step, enabling the inorganic halide to react with the organic halide, and then heating, drying and annealing to form the mesoporous perovskite film with the mesoporous structure; the annealing time is 3-5min, and the heating temperature is 60-80 ℃.

The research shows that the inorganic halide layer (inorganic halide film) formed by the inorganic halide precursor liquid is a compact structure, and the surface of the inorganic halide layer is bright yellow. After intensive research, the surface of an inorganic halide film is changed into light yellow after being treated by Lewis base, because the inorganic halide and the Lewis base can form an addition product of halide and Lewis base molecules under the action of Lewis acid and base, so that the volume of the film is expanded; lewis base molecules in the addition product are escaped in the subsequent heating and annealing process, so that the addition product film with a mesoporous structure is formed, and favorable conditions are created for preparing the perovskite film with the mesoporous structure later.

The inorganic halide is PbX₂X is Cl, Br or I; the organic solvent is DMF, DMSO, GBL or a mixture of any two.

The Lewis base is pyridine organic solvent. Preferably, the pyridine-based organic solvent is 4-tert-butylpyridine (4-TBP).

In the step (iv) of the present invention, the treatment of the inorganic halide layer with the isopropanol solution of the organic halide is as follows: spin-coating an isopropanol solution of an organic halide to the surface of the treated inorganic halide layer, and then heating and drying; or; and soaking the treated inorganic halide layer into an isopropanol solution of the organic halide, and then heating and drying.

In the step I of the invention, 300mg to 550mg of PbX is added₂Dissolving in 3ml-6ml of organic solvent, preferably PbX₂The concentration of (A) is 0.8-1.2 mol/ml; in the second step, the deposition speed of the inorganic halide precursor solution is 3500rpm-4500rpm, and the volume of the pyridine organic solvent is 50 muL-200 muL; in the third step, the volume of the isopropanol solution of the organic halide is 20-100 mul, the mass fraction of the organic halide is 5-40 mg/ml, and the concentration of the organic halide is 8-15 mg/ml. Preferably, PbX₂The amount of (2) used was 300mg, and the amount of the organic solvent used was 3 ml. Preferably, the organic halide is used in an amount of 50mg and the isopropyl alcohol is used in an amount of 5 ml.

The heating and drying conditions in the step IV of the invention are as follows: temperature: 60-80 ℃, time: 3-5 min.

In the second step of the invention, the steam treatment time is 5min-30min, so as to ensure that the volume of the inorganic halide layer after the treatment is at least twice of the volume of the inorganic halide layer which is just deposited; after the step two, the volume expansion ratio of the addition product compared with the inorganic halide layer is positively correlated with the mesoporous aperture of the addition product; the thickness of the adduct is controlled by controlling the time of steam treatment, so that the value of the mesoporous aperture of the adduct is finally adjusted. Only in this case, the mesoporous structure of the mesoporous perovskite thin film can be effectively formed. If this condition is not satisfied, a dense large-grain perovskite structure is formed. Preferably, the time of the steam treatment of the Lewis base is 5 to 10min and the volume of the organic solution of the desired Lewis base in a closed vessel having a volume of 45ml is 10 to 20. mu.l.

In step (c) of the present invention, the organic halide is RNH₃X or formamidine halide; at RNH₃In X, R is C₁-C₁₀X is Cl, Br or I. R is methylamino, ethylamino, propylamino, butylamino, pentylamino or hexylamino.

The application of the mesoporous perovskite thin film is characterized in that: the optical device is used as an absorption layer of the optical device.

The thickness of the perovskite thin film with the mesoporous structure prepared by the method is 400-6000nm, and compared with the traditional experimental method, the perovskite thin film with the mesoporous structure prepared by the method does not contain a large amount of PbX₂Residual, the heating time is effectively shortened; the mesoporous perovskite thin film prepared by the method has the advantages that the light absorption capacity is effectively enhanced, the electron transmission capacity is effectively improved, and a new idea and a new method are provided for preparing high-performance perovskite photoelectric devices.

Drawings

FIG. 1 is CH of comparative group of the present invention₃NH₃PbI₃Layer SEM images.

FIG. 2 shows CH in example 5 of the present invention₃NH₃PbI₃Layer SEM images.

FIG. 3 is CH of comparative group of the present invention₃NH₃PbI₃Layer PL spectrum.

FIG. 4 is CH in example 5 of the present invention₃NH₃PbI₃Layer PL spectrum.

FIG. 5 is CH of comparative group of the present invention₃NH₃PbI₃Layer absorption spectrum.

FIG. 6 shows CH in example 5 of the present invention₃NH₃PbI₃Layer absorption spectrum.

FIG. 7 is CH of comparative group of the present invention₃NH₃PbI₃Transient spectral profile of the layer.

FIG. 8 shows CH in example 5 of the present invention₃NH₃PbI₃Transient spectral pattern of the layer.

FIG. 9 is CH of comparative group of the present invention₃NH₃PbI₃Layer SEM cross-sectional view.

FIG. 10 shows CH in example 5 of the present invention₃NH₃PbI₃Layer SEM cross-sectional view.

Detailed Description

The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.

And (4) comparing the groups.

See fig. 1, 3, 5, 7, 9.

The comparison group is a preparation method of a perovskite thin film, and the preparation method comprises the following specific steps:

step 1): mixing 300mg-550mg of PbI₂Dissolving in 3ml-6ml DMF, heating and stirring until solute is completely dissolved to form PbI₂A precursor solution;

preferably, PbI is used in the step₂The amount of DMF used is 300mg, and the amount of DMF used is 3 ml;

step 2): 30mg-50mg of CH₃NH₃I is dissolved in 3-5ml volume of isopropanol solution and stirred until completely dissolved to form CH₃NH₃I isopropanol solution (CH)₃NH₃The mass fraction of I is 10mg/ml-15 mg/ml);

CH in this example₃NH₃The using amount of I is 50mg, and the using amount of isopropanol is 5 ml;

step 3): the PbI prepared in the step 1) is added₂Depositing the precursor solution on a substrate, and then annealing to obtain PbI₂Layer preparation is completed;

preferably, PbI₂The rotating speed of the spin coating of the precursor liquid in the deposition process is 3500rpm-4500 rpm;

step 4): subjecting CH prepared in step 2)₃NH₃I isopropanol solution (CH)₃NH₃I the mass fraction is 10mg/ml-15 mg/ml)

And the PbI prepared in the step 3) is₂The layers are reacted and then dried by heating to make PbI₂The layer is converted into a mesoporous perovskite film; or the PbI prepared in the step 3) is completely used₂Soaking the layer in CH₃NH₃I, reacting in isopropanol solution for 10-60s, then heating and drying, and completely converting into a perovskite film after annealing;

preferably, the drying conditions in step 4) are: temperature: 60-80 ℃, time: 3-5 min.

The perovskite thin film after being prepared is observed in shape, and the result is shown in figure 1, and other photoelectric characteristics of the perovskite thin film are shown in figures 1, 3, 5, 7 and 9.

Example 1.

The embodiment is a mesoporous perovskite thin film and a preparation method thereof, and the preparation method comprises the following specific steps:

step 3): the PbI prepared in the step 1) is added₂Depositing the precursor solution on a substrate, then placing the substrate in a closed container containing 4-TBP steam for steam treatment for 5min, and then carrying out drying annealing to the PbI₂Layer preparation is completed;

preferably, PbI₂The rotating speed of spin coating during the deposition of the precursor solution is 3500rpm-4500 rpm;

And the PbI prepared in the step 3) is₂The layers are reacted and then dried by heating to make PbI₂The layer is converted into a mesoporous perovskite film; or the PbI prepared in the step 3) is completely used₂Soaking the layer in CH₃NH₃And (3) reacting in isopropanol solution of the I for 10-60s, then heating and drying, and completely converting into the mesoporous perovskite thin film after annealing.

Example 2.

step 1): 300mg-550mg of PbBr₂Dissolving in 3-6 ml DMSO, heating and stirring to dissolve solute completely to form PbBr₂A precursor solution;

preferably, PbBr is used in the step₂The usage amount of (1) is 300mg, and the usage amount of DMSO is 3 ml;

step 2): 30mg-50mg of CH₃NH₃Dissolving Br in 3-5ml isopropanol solution, stirring to dissolve completely to form CH₃NH₃Isopropanol solution of Br (CH)₃NH₃The mass fraction of Br is 10mg/ml-15 mg/ml);

preferably, CH in this step₃NH₃The using amount of Br is 50mg, and the using amount of isopropanol is 5 ml;

step 3): PbBr prepared in the step 1)₂Depositing the precursor solution on a substrate, then placing the substrate in a closed container containing 4-TBP steam for 10min, and then carrying out drying annealing to the PbBr₂Layer preparation is completed;

preferably, PbBr₂The rotating speed of spin coating during the deposition of the precursor solution is 3500rpm-4500 rpm;

step 4): subjecting CH prepared in step 2)₃NH₃I isopropanol solution (CH)₃NH₃The mass fraction of Br is 10mg/ml-15 mg/ml)

And PbBr prepared in the step 3)₂The layers are reacted and then dried by heating to make PbBr₂The layer is converted into a mesoporous perovskite film; or PbBr after the preparation in the step 3) is finished₂Soaking the layer in CH₃NH₃Reacting in isopropanol solution of Br for 10-60s, heating and drying, and completely converting into the mesoporous perovskite film after annealing.

Example 3.

step 1): mixing 300mg-550mg of PbI₂Dissolving in 3-6 ml DMF, heating and stirring to dissolve solute completely, and preparing PbI₂A precursor solution;

step 2): 30mg-50mg of CH₃NH₃I is dissolved in 3-5ml of isopropanol solution and stirred until completely dissolved to form CH₃NH₃I isopropanol solution (CH)₃NH₃The mass fraction of I is 10mg/ml-15 mg/ml);

preferably, CH in this step₃NH₃The using amount of I is 50mg, and the using amount of isopropanol is 5 ml;

step 3): the PbI prepared in the step 1) is added₂Depositing the precursor solution on a substrate, then placing the substrate in a closed container containing 4-TBP steam for steam treatment for 15 min, and then drying to obtain PbI₂Layer preparation is completed;

Example 4.

Example 5:

see fig. 2, 4, 6, 8, 10.

step 3): the PbI prepared in the step 1) is added₂Depositing the precursor solution on a substrate, then placing the substrate in a closed container containing 4-TBP steam for steam treatment for 25min, and then drying to obtain PbI₂Layer preparation is completed; PbI in this case₂The thickness of the layer reaches the PbI of the comparison group₂More than 5 times of the layer thickness;

The photoelectric properties of the prepared film are shown in fig. 2, 4, 6, 8 and 10.

Compared with a comparison group, referring to an SEM image, an effective mesoporous structure is formed after the treatment of 4-TBP steam; see PL

The peak value in the prepared thin film PL spectrogram is improved, which shows that the transmission speed of the current carrier under the mesoporous structure is obviously slowed down. With reference to the absorption spectrum, the film under the mesoporous structure has obviously improved light absorption at the wave band of 300-500nm compared with the contrast group. Referring to a transient spectrogram, the carrier attenuation rate under the mesoporous structure is obviously reduced.

In addition, it should be noted that the specific embodiments described in the present specification may be different in the components, the shapes of the components, the names of the components, and the like, and the above description is only an illustration of the structure of the present invention. Equivalent or simple changes in the structure, characteristics and principles of the invention are included in the protection scope of the patent. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.

Claims

1. a preparation method of mesoporous perovskite film, is characterized in that: comprise the steps:

① Dissolve the inorganic halide in an organic solvent, heat and stir until it is completely dissolved to form an inorganic halide precursor;

② Deposit the inorganic halide precursor solution obtained in step ① on the substrate to form an inorganic halide layer, and then use a Lewis base to steam the inorganic halide layer in a closed container for a period of time, and a Lewis acid-base addition reaction occurs to form The adduct of the inorganic halide layer and the Lewis base, and then heating and drying the adduct to form mesopores in the adduct. So far, the treatment of the inorganic halide layer is completed; in this step, the annealing time is 10-20min, The heating temperature is 70-80℃;

③ Dissolving the organic halide in isopropanol to form an isopropanol solution of the organic halide;

④ The inorganic halide layer after the treatment in step ② is treated with an isopropanol solution of an organic halide, and then heated and dried to form a mesoporous perovskite film with a mesoporous structure;

The inorganic halide is PbX ₂ , and X is Cl, Br or I; the organic solvent is DMF, DMSO, GBL or a mixture of any two;

Lewis base is 4-TBP;

In step 4., the method of treating the inorganic halide layer by the isopropanol solution of the organic halide is as follows: the isopropanol solution of the organic halide is spin-coated to the surface of the inorganic halide layer after the treatment is completed, and then heated and dried;

Or; soak the treated inorganic halide layer in the isopropanol solution of organic halide, then heat and dry;

In step ①, 300mg-550mg of PbX ₂ is dissolved in 3ml-6ml of organic solvent; in step ②, the rotational speed of the inorganic halide precursor solution during deposition is 3500rpm-4500rpm, and the volume of the pyridine organic solvent is 50μL-200μL ; In step ③, the volume of the isopropanol solution of the organic halide is 20 μL-100 μL, and the mass fraction of the organic halide is 5 mg/ml-40 mg/ml;

The heating and drying conditions in step ④ are: temperature: 60-80°C, time: 3-5min;

In step ②, the steam treatment time is 5min-30min to ensure that the volume of the inorganic halide layer after the treatment is at least twice the volume of the just-deposited inorganic halide layer; The volume expansion ratio of the material layer is positively correlated with the mesopore diameter of the adduct; by controlling the time of steam treatment, the thickness of the adduct can be controlled, so as to finally adjust the value of the mesopore diameter of the adduct; step ③ In RNH 3 X, the organic halide is RNH ₃ X or formamidine halide; in RNH ₃ X, R is a C1-C10 organic group, and X is Cl, Br or I.

2. The application of the mesoporous perovskite thin film prepared by the preparation method as claimed in claim 1 is characterized in that: it is used as the absorption layer of the optoelectronic device.