WO2015165259A1 - Solution-processible organic-inorganic planar heterojunction solar cell and preparation method therefor - Google Patents

Abstract

A solution-processible organic-inorganic planar heterojunction solar cell and a preparation method therefor through solution processing. The solar cell comprises a substrate, an anode, an anode interface layer, a photoactivity layer, a cathode interface layer, and a cathode that are sequentially stacked. The material of the photoactivity layer is an inorganic material that is soluble in a solvent and is of a perovskite structure, and performance of the material can be improved by adding polymer additives. The photoactivity layer is made of the solution-processible perovskite organic-inorganic hybrid material, and the anode interface layer and the cathode interface layer are processed through organic material solutions. By means of the method, the problem that energy consumption is high in cell device processing is effectively solved, large-scale production is achieved, and high efficiency is achieved; and the defects in the prior art that the inorganic material needs to be processed at high temperature and the cost of the materials in the organic solar cell is high are overcome. The material and the method can be applied, as a novel material and method, to solar cells.

Description

Solution-processed organic-inorganic planar heterojunction solar cell and preparation thereof Technical field

The invention belongs to the technical field of optoelectronic devices, and particularly relates to a solution-processed organic-inorganic planar heterojunction solar cell and a solution processing and preparation method thereof.

Background technique

As the global demand for energy increases year by year, the traditional energy sources such as oil and coal are depleted, and the need to protect the earth's ecological environment, more and more scientists around the world focus their research on hydrogen, solar energy, etc. Inexhaustible renewable energy.

Inorganic materials-based solar cells such as inorganic silicon, gallium arsenide, and indium phosphide have already dominated the market. However, due to their high requirements on material purity, high energy consumption and pollution are generated during processing. And its price is very expensive, so in the pursuit of low cost and green, today its large-scale application is limited.

Dye-sensitized solar cells have been hampered by packaging problems since they achieved 12% efficiency in the early 1990s. The solid electrolyte developed in recent years and the doped polymer hole material can solve the packaging problem of the dye-sensitized battery well, but the efficiency is also reduced. In addition, the dye-sensitized solar cell requires a high temperature treatment of the precursor of TiO ₂ during processing to convert it into an inorganic semiconductor of TiO ₂ . These two points are major obstacles in the commercialization of dye-sensitized solar cells.

Organic-inorganic hybrid semiconductor materials with perovskite structure have gradually attracted attention in the last century. They have the advantages of high mobility, good absorption, and processing in a variety of ways. Early researchers focused on high mobility and prepared devices such as transistors. In recent years, with the gradual deepening of research, some scholars have begun to use the organic-inorganic hybrid materials of perovskite structure to prepare dye-sensitized batteries. In 2009, the Tsutomu Miyasaka research group first prepared a dye-sensitized solar cell using a perovskite-structured organic-inorganic hybrid material as a photoactive layer. Its efficiency reached 3.81% (J. Am. Chem. Soc. 2009, 131, 6050).

In the preparation process of dye-sensitized solar cells, high temperature is needed to convert the precursor of TiO ₂ into inorganic semiconductor, and the efficient battery device needs to be prepared by evaporation method, and the preparation process is complicated. In contrast, organic solar cells can be processed at low temperature and full solution, which not only reduces production energy consumption but also enables large-scale production. In addition, organic solar cells can be fabricated with flexible devices that are lightweight and can meet different needs. Its current efficiency has exceeded 10% (Nat.Commun. 2013, 4, 1446). However, the production cost of organic solar cell materials is high and it is difficult to industrialize batch production.

Summary of the invention

In order to overcome the shortcomings of the above-mentioned prior art inorganic materials requiring high temperature processing and the high cost of organic materials, the primary object of the present invention is to provide a solution-processed organic-inorganic planar heterojunction solar cell. The photoactive layer of the solar cell is prepared by a solution processing method, has a high-performance perovskite structure, realizes low temperature solution processing of a solar cell, and the addition of a polymer additive in the photoactive layer greatly improves the open circuit of the solar cell. Voltage and device performance.

Another object of the present invention is to provide a solution processing and preparation method for the above-described solution-processed organic-inorganic planar heterojunction solar cell.

The object of the invention is achieved by the following scheme:

A solution processed organic-inorganic planar heterojunction solar cell comprising a substrate, an anode, an anode interface layer, a photoactive layer, a cathode interface layer, and a cathode, which are sequentially stacked.

The material of the photoactive layer is an inorganic material which is soluble in a solvent and has a perovskite structure.

The photoactive layer is a blend of compound A and compound B in a molar ratio of 1:1 to 10:1.

The compound A is a halogen-containing organic or inorganic salt, preferably at least one of the following compounds: CH ₃ NH ₃ I, CH ₃ NH ₃ Br, CH ₃ NH ₃ Cl, CH ₃ CH ₂ NH ₃ I, CH ₃ CH ₂ NH ₃ Br, CH ₃ CH ₂ NH ₃ Cl, CH ₃ CH ₂ CH ₂ NH ₃ I, CH ₃ CH ₂ CH ₂ NH ₃ Br, CH ₃ CH ₂ CH ₂ NH ₃ Cl, CsI, CsBr, CsCl, CH(NH ₂ ) ₂ I, CH(NH ₂ ) ₂ Br, CH(NH ₂ ) ₂ Cl, CH ₃ CH(NH ₂ ) ₂ I, CH ₃ CH(NH ₂ ) ₂ Br, CH ₃ CH ( NH ₂ ) ₂ Cl.

The halogen-containing compound B is a metal inorganic salt, preferably at least one of the following _{compounds: PbI 2, PbBr 2, PbCl} 2, SnI 2, SnBr 2, SnCl 2, GeI 2, GeBr 2, GeCl 2.

The invention also provides a solution processing method of the photoactive layer, which is specifically as follows: compound A and compound B are mixed in proportion, dissolved in an organic solvent, heated and reacted, and coated on the anode interface layer to form a photoactive layer.

The organic solvent is preferably cyclohexanone, cyclopentanone, γ-butyrolactone, δ-valerolactone, γ-valerolactone, ε-caprolactone, N,N-dimethylformamide, two At least one of methyl acetamide, dimethyl sulfoxide and N-methyl pyrrolidone.

The heating reaction is preferably carried out at 60 ° C for 12 h.

The coating method can be spin coating, brush coating, spray coating, dip coating, roll coating, screen printing, printing or ink jet printing.

The photoactive layer in the solution-processed organic-inorganic planar heterojunction solar cell of the present invention is a high performance perovskite The structure is prepared by a solution method, and a highly efficient solar cell can be obtained.

In order to better improve the open circuit voltage and device performance of the solution-processed organic-inorganic planar heterojunction solar cell of the present invention, a series of polymer additives may be added to the photoactive layer.

The polymer additive is a polymer having a linear structure or a branched structure which is soluble in an organic solvent.

Preferably, the polymer additive has at least one of the structures shown in the formulas (I) to (VI):

Wherein n is a natural number from 1 to 100000000; R ₁ is a linear, branched, alkoxy chain having from 1 to 6 carbon atoms, wherein one or more carbon atoms may be oxygen atoms, hydroxyl groups, amino groups, aromatic groups Substituent, ester group, carbonyl group; R ₂ , R ₃ are a hydrogen atom or a linear, branched, cyclic alkyl chain having 1 to 20 carbon atoms, an alkoxy chain, wherein one or more carbon atoms may be It is substituted by an oxygen atom, a hydroxyl group, an amino group, an aryl group, an ester group, or a carbonyl group.

The polymer additive is preferably P2O having the following structure.

The amount of the polymer additive used is 0.5 to 10% by mass of the sum of the compound A and the compound B.

The polymer additive can be a synthetic synthetic or a commercial product.

Preferably, the solution processing method prepares a photoactive layer, and the polymer additive is mixed with the compound A and the compound B, and then dissolved and coated.

The introduction of the polymer additive into the photoactive layer can effectively improve the film formation of the photoactive layer film. The polymer additive used in the present invention has a structure similar to a solvent, and the polymer additive can significantly improve the film forming property of the photoactive layer film by interaction with a solvent and interaction with a material of the photoactive layer at the time of film formation. The use of the polymer additive of the present invention can significantly improve the open circuit voltage and energy conversion efficiency of the battery device.

In the solar cell of the present invention, the cathode interface layer is preferably carbon 60 and a derivative thereof (such as [6,6]-phenyl-C61-butyric acid At least one of methyl ester), carbon 70 and derivatives thereof (such as [6,6]-phenyl-C71-butyric acid methyl ester), conjugated polymers, inorganic semiconductor nanoparticles, graphene and derivatives thereof.

The cathode material is preferably aluminum, silver, gold, calcium/aluminum alloy or calcium/silver alloy.

The anode interface layer of the present invention is preferably an organic conjugated polymer (such as poly 3,4-ethylenedioxythiophene/polystyrene sulfonate) or an inorganic semiconductor. The anode interface layer may be a composite interface layer after the addition of nanoparticles to improve light absorption.

The anode of the present invention is preferably a metal, a metal oxide (such as an indium tin oxide conductive film (ITO), doped tin dioxide (FTO), zinc oxide (ZnO), indium gallium zinc oxide (IGZO)) and graphene. At least one of its derivatives.

The substrate of the present invention is preferably a glass, flexible material (such as polyimide, polyethylene terephthalate, ethylene terephthalate, polyethylene naphthalate or other polyester materials). At least one of a metal, an alloy, and a stainless steel film.

The invention also provides a solution processing method for the above solution-processed organic-inorganic planar heterojunction solar cell, comprising the following steps:

(1) spin coating an anode interface layer on the surface of the anode coated on the substrate;

(2) coating a layer of photoactive layer on the anode interface layer by solution processing;

(3) coating a layer of a cathode interface layer on the photoactive layer by solution processing;

(4) A metal layer is deposited on the cathode interface layer as a cathode.

The invention innovatively combines the advantages of a planar heterojunction solar cell and an organic solar cell based on a perovskite organic-inorganic hybrid material, and provides a photoactive layer using a solution processable perovskite organic-inorganic The hybrid material, the anode interface layer and the cathode interface layer are planar heterojunction solar cell devices processed by an organic material solution. This combination can effectively improve the energy consumption and large-area production problems in the processing of battery devices, and can achieve higher efficiency. Compared with inorganic solar cells and dye-sensitized solar cells, the disadvantages of high-temperature processing of inorganic materials are overcome, and the disadvantages of high material cost are overcome compared to organic solar cells. It can be used as a new type of material and method in solar cells.

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

(1) The invention adopts low temperature solution processing technology to prepare solar cells, has simple preparation process, low energy consumption and low preparation cost.

(2) The present invention employs an organic-inorganic hybrid material as a photoactive layer, which has a broad absorption in the visible and near-infrared regions, and has a high absorption coefficient, which is superior to most organic materials.

(3) The invention uses the inorganic material as the photoactive layer to obtain the solar cell performance with high efficiency, and the addition of the polymer additive can significantly improve the open circuit voltage and energy conversion efficiency of the device.

DRAWINGS

1 is a schematic structural view of an organic-inorganic planar heterojunction solar cell of the present invention, wherein 1 is a substrate, 2 is an anode, 3 is an anode interface layer, 4 is a photoactive layer, 5 is a cathode interface layer, and 6 is cathode.

2 is an ultraviolet-visible-near infrared absorption spectrum of the photoactive layer (CH ₃ NH ₃ PbI ₃ ) of the present invention.

Figure 3 is a photoluminescence spectrum of the photoactive layer (CH ₃ NH ₃ PbI ₃ ) of the present invention.

4 is an external quantum efficiency of an organic-inorganic planar heterojunction solar cell of the present invention (with CH ₃ NH ₃ PbI ₃ as a photoactive layer).

Figure 5 is an X-ray film diffraction pattern of the photoactive layer (CH ₃ NH ₃ PbI ₃ ) of the present invention.

Figure 6 is a scanning electron micrograph of an organic-inorganic planar heterojunction solar cell of the present invention (with CH ₃ NH ₃ PbI ₃ as a photoactive layer) with different ratios of photoactive layer polymer additives.

Detailed ways

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

Example 1: Preparation of Photoactive Layer Material

CH ₃ NH ₃ I, CH ₃ NH ₃ Br, CH ₃ NH ₃ Cl, CH ₃ CH ₂ NH ₃ I, CH ₃ CH ₂ NH ₃ Br, CH ₃ CH ₂ NH ₃ Cl, CH ₃ CH of the compound A ₂ CH ₂ NH ₃ I, CH ₃ CH ₂ CH ₂ NH ₃ Br, CH ₃ CH ₂ CH ₂ NH ₃ Cl, CH(NH ₂ ) ₂ I, CH(NH ₂ ) ₂ Br, CH(NH ₂ ) ₂ Cl CH ₃ CH(NH ₂ ) ₂ I, CH ₃ CH(NH ₂ ) ₂ Br, CH ₃ CH(NH ₂ ) ₂ Cl. The synthesis was carried out according to the method in the literature (J. Am. Chem. Soc. 2012, 134, 17396-17399).

The synthesis of CH ₃ NH ₃ PbI ₃ is carried out by reacting CH ₃ NH ₃ I with PbI ₂ in γ-butyrolactone or other organic solvent, as follows:

CH ₃ NH ₃ I (32 mg) and PbI ₂ (93 mg) were blended and dissolved in 1 mL of γ-butyrolactone, heated to 60 ° C, and stirred for 12 hours to obtain a photoactive layer material.

The preparation of the photoactive layer material containing the polymer additive is as follows:

To the above solution, a polymer additive of 0.5 to 10% by weight based on the total mass of CH ₃ NH ₃ I and PbI _{2 is} added, and heated at 60 ° C to dissolve slowly to obtain a photoactive layer material containing a polymer additive.

Preparation of CH ₃ NH ₃ PbI _x Cl _3-x and CH ₃ NH ₃ PbI _x Br _3-x (x less than 3, greater than 0) by dissolving CH ₃ NH ₃ I and PbCl ₂ , PbBr _{2 respectively} In the heating, stirring is obtained, and the raw material dosage ratio is appropriately adjusted according to the required x ratio.

The preparation method of the photoactive layer material by the other combination of the other compound A and the compound B is the same as above.

Example 2: Preparation of an organic-inorganic heterojunction solar cell:

ITO conductive glass, square resistance ~ 20 ohm / square centimeter, pre-cut into 15 mm × 15 mm square. It is sequentially ultrasonically cleaned with acetone, micron-sized semiconductor special detergent, deionized water, and isopropyl alcohol. After nitrogen purge, it is placed in a constant temperature oven for use. Prior to use, the ITO glass sheets were bombarded with plasma for 10 minutes in an oxygen plasma etch oven. PEDOT: PSS aqueous dispersion (about 1%) was purchased from Bayer, and the buffer layer was spin-coated with a high speed machine (KW-4A). The thickness was determined by the solution concentration and rotation speed. Surface profiler (Tritek Alpha-Tencor- Model 500) measured monitoring. After film formation, the solvent residue and the vertical film were removed in a constant temperature vacuum oven. It is preferable that the film thickness of PEDOT:PSS is about 40 nm on the ITO substrate. The cathode interface layer is obtained by spin coating a layer of PC ₆₁ BM on the surface of the photoactive layer, and the PC ₆₁ BM solution is prepared by a solvent such as chlorobenzene, dichlorobenzene, toluene, chloroform or xylene, and the concentration ranges from 1 to 20 mg/mL.

The cell structure of the device of the present invention is as shown in FIG. 1. A 40 nm thick PEDOT:PSS film is spin-coated on the ITO, and then a mass concentration of 10% photoactive layer material (solvent is γ-butyrolactone) is disposed. It was spin-coated onto the PEDOT:PSS layer at 3000 rpm, then annealed at 100 °C for 15 min, and then a 25 nm thick layer of PC ₆₁ BM was spin-coated thereon. Finally, an aluminum electrode is evaporated by evaporation. The photoactive layer material was CH ₃ NH ₃ PbI ₃ prepared in Example 1.

Alternatively, 0.5 to 10% by weight of the polymer additive P2O is added to the photoactive layer material, followed by spin coating.

The prepared photoactive layer was subjected to ultraviolet-visible-near infrared spectroscopy and photoluminescence spectroscopy, and the results are shown in Fig. 2 and Fig. 3. The prepared device battery was subjected to an external quantum efficiency test, and the results are shown in Fig. 4. The X-ray film diffraction pattern of the photoactive layer (CH ₃ NH ₃ PbI ₃ ) was carried out, and the results are shown in Fig. 5. The performance of the photovoltaic device was measured for a N, N-dimethylformamide solvent system and a battery device with different P2O addition amounts. The results are shown in Table 1. The photoactive layer obtained by different solvent systems and different polymer additives was observed by scanning electron microscopy. The results are shown in Fig. 6.

Table 1 Battery device performance indicators of different P2O additions

	Voc(V)	Jsc (mA/cm 2 )	FF (%)	PCE (%)
					0wt%P2O	0.71	7.47	44.6	2.37
1wt% P2O	0.93	7.84	67.3	4.91
					1.5wt% P2O	1.07	8.46	64.5	5.83
3wt% P2O	1.1	6.8	62.3	4.66
					5wt% P2O	1.1	7.04	54.5	4.22
7wt% P2O	1.01	2.55	42.4	1.09

It can be seen from Table 1 and FIG. 6 that the organic-inorganic heterojunction solar cell prepared by the present invention can improve the film forming property and device performance of the perovskite material by changing the amount of the additive, and the amount of the polymer additive increases. The film-forming properties and device properties of the resulting photoactive layer material are improved and improved, wherein the open circuit voltage and device efficiency can be increased by up to 54% and 146, respectively.

Example 3: Photovoltaic performance of organic-inorganic heterojunction solar cells of different photoactive layer materials

Organic-inorganic preparations prepared from CH ₃ NH ₃ PbI ₃ , CH ₃ NH ₃ PbI _x Cl _3-x and CH ₃ NH ₃ PbI _x Br _3-x (x less than 3, greater than 0) as photoactive layer materials The photovoltaic performance of the heterojunction solar cell was measured, and the results are shown in Table 2.

Table 2 Battery device performance indicators of different photoactive layer materials

	Voc(V)	Jsc (mA/cm 2 )	FF (%)	PCE (%)
					CH 3 NH 3 PbI 3	0.71	7.47	44.6	2.37
CH 3 NH 3 PbI x Cl 3-x	0.94	10.19	64.9	6.21
					CH 3 NH 3 PbI x Br 3-x	1.01	2.55	42.4	1.09

It can be seen from Table 2 that by changing the composition of the active layer material and increasing the content of bromine or chlorine therein, the device performance can be effectively improved.

It can be seen from Examples 1 to 3 that the organic-inorganic heterojunction solar cell of the present invention can be prepared by a solution processing method, and the film-forming property of the perovskite material can be remarkably improved by adding a photoactive layer polymer additive. Increase the open circuit voltage of the device and ultimately improve the photoelectric conversion performance of the device.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and combinations thereof may be made without departing from the spirit and scope of the invention. Simplifications should all be equivalent replacements and are included in the scope of the present invention.

Claims (10)

1. A solution-processed organic-inorganic planar heterojunction solar cell characterized by comprising a substrate, an anode, an anode interface layer, a photoactive layer, a cathode interface layer and a cathode which are sequentially stacked;

   The material of the photoactive layer is an inorganic material which is soluble in a solvent and has a perovskite structure.
2. The solution-processed organic-inorganic planar heterojunction solar cell according to claim 1, wherein the photoactive layer is a blend of compound A and compound B in a molar ratio of 1:1 to 10:1. The compound A is a halogen-containing organic or inorganic salt; and the compound B is a halogen-containing metal inorganic salt.
3. The solution-processed organic-inorganic planar heterojunction solar cell according to claim 2, wherein the compound A is at least one of the following compounds: CH ₃ NH ₃ I, CH ₃ NH ₃ Br, CH ₃ NH ₃ Cl, CH ₃ CH ₂ NH ₃ I, CH ₃ CH ₂ NH ₃ Br, CH ₃ CH ₂ NH ₃ Cl, CH ₃ CH ₂ CH ₂ NH ₃ I, CH ₃ CH ₂ CH ₂ NH ₃ Br, CH ₃ CH ₂ CH ₂ NH ₃ Cl, CsI, CsBr, CsCl, CH(NH ₂ ) ₂ I, CH(NH ₂ ) ₂ Br, CH(NH ₂ ) ₂ Cl, CH ₃ CH(NH ₂ ) ₂ I, CH ₃ CH(NH ₂ ) ₂ Br, CH ₃ CH(NH ₂ ) ₂ Cl; the compound B is at least one of the following compounds: PbI ₂ , PbBr ₂ , PbCl ₂ , SnI ₂ , SnBr ₂ , SnCl ₂ , GeI ₂ , GeBr ₂ , GeCl ₂ .
4. The solution-processed organic-inorganic planar heterojunction solar cell according to claim 1, wherein the photoactive layer is obtained by a solution processing method, as follows: compound A and compound B are mixed in proportion and dissolved. The organic solvent, after heating the reaction, is coated on the anode interface layer to form a photoactive layer.
5. The solution-processed organic-inorganic planar heterojunction solar cell according to claim 4, wherein the organic solvent is cyclohexanone, cyclopentanone, γ-butyrolactone, δ-valerolactone, At least one of γ-valerolactone, ε-caprolactone, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide and N-methylpyrrolidone; said heating reaction The reaction was carried out at 60 ° C for 12 h.
6. The solution-processed organic-inorganic planar heterojunction solar cell according to claim 1, wherein said photoactive layer contains a series of polymer additives; said polymer additive is soluble in organic solvent. A polymer having a linear structure or a branched structure.
7. The solution-processed organic-inorganic planar heterojunction solar cell according to claim 6, wherein the amount of the polymer additive used is 0.5 to 10% by mass of the sum of the compound A and the compound B.
8. The solution-processed organic-inorganic planar heterojunction solar cell according to claim 6, wherein said polymer additive has at least one of the structures represented by formulae (I) to (VI):

   

   Wherein n is a natural number from 1 to 100000000; R ₁ is a linear, branched, alkoxy chain having from 1 to 6 carbon atoms, wherein one or more carbon atoms may be oxygen atoms, hydroxyl groups, amino groups, aromatic groups Substituent, ester group, carbonyl group; R ₂ , R ₃ are a hydrogen atom or a linear, branched, cyclic alkyl chain having 1 to 20 carbon atoms, an alkoxy chain, wherein one or more carbon atoms may be It is substituted by an oxygen atom, a hydroxyl group, an amino group, an aryl group, an ester group, or a carbonyl group.
9. The solution-processed organic-inorganic planar heterojunction solar cell according to claim 1, wherein said cathode interface layer is carbon 60 and derivatives thereof, carbon 70 and derivatives thereof, conjugated polymers, At least one of inorganic semiconductor nano, graphene and derivatives thereof; the cathode material is aluminum, silver, gold, calcium/aluminum alloy or calcium/silver alloy; and the anode interface layer is an organic conjugated polymer Or an inorganic semiconductor; the anode is at least one of a metal, a metal oxide, and graphene and a derivative thereof; the substrate is at least one of a glass, a flexible material, a metal, an alloy, and a stainless steel film.
10. The method for preparing a solution-processed organic-inorganic planar heterojunction solar cell according to claim 1, comprising the steps of:

    (1) spin coating an anode interface layer on the surface of the anode coated on the substrate;

    (2) coating a layer of photoactive layer on the anode interface layer by solution processing;

    (3) coating a layer of a cathode interface layer on the photoactive layer by solution processing;

    (4) A metal layer is deposited on the cathode interface layer as a cathode.

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