CN111384243A

CN111384243A - Perovskite solar cell and manufacturing method thereof

Info

Publication number: CN111384243A
Application number: CN201910096554.9A
Authority: CN
Inventors: 徐为哲; 许弘儒; 王凯正
Original assignee: Industrial Technology Research Institute ITRI
Current assignee: Industrial Technology Research Institute ITRI
Priority date: 2018-12-27
Filing date: 2019-01-30
Publication date: 2020-07-07
Anticipated expiration: 2039-01-30
Also published as: CN111384243B; TWI692879B; TW202025505A

Abstract

A perovskite solar cell. The perovskite solar cell comprises a substrate, a first semiconductor layer arranged on the substrate, an induced crystal nucleus layer arranged on the first semiconductor layer, a perovskite absorption layer covering the induced crystal nucleus layer and the first semiconductor layer, a second semiconductor layer arranged on the perovskite absorption layer, and an electrode layer arranged on the second semiconductor layer. The invention further provides a manufacturing method for manufacturing the perovskite solar cell.

Description

Perovskite solar cell and manufacturing method thereof

Technical Field

The present invention relates to perovskite solar cells, and in particular to perovskite solar cells comprising an induced nucleation layer.

Background

In recent years, the solar photovoltaic industry has been rapidly developed due to global climate change, environmental pollution problems, and increasing shortage of resources, and under the warning of rising environmental awareness and energy crisis. The power generation principle of the solar cell is to convert light energy into electric energy by using the photoelectric effect of a semiconductor material. Specifically, when light is irradiated to a semiconductor material, photons are generated, which in turn cause electron-hole pairs to be generated inside the semiconductor material, and then the electrons and holes are respectively transported to two opposite electrodes by an internal electric field, thereby generating a voltage. At this time, if the two electrodes are connected to an external circuit, a current is generated.

At present, a new semiconductor material with a perovskite (perovskite) structure is proposed, which has the advantages of high photoelectric conversion efficiency, low preparation cost and the like, and is not easy to cause pollution. Therefore, research techniques for applying perovskite materials to solar cells are growing. However, the biggest problem facing the application at present is poor solar cell stability on perovskite.

Therefore, it is highly desirable to improve the stability of the perovskite absorption layer to improve the applicability thereof.

Disclosure of Invention

The invention provides a perovskite solar cell. The perovskite solar cell structure comprises: the device comprises a substrate, a first semiconductor layer, an induced crystal nucleus layer, a perovskite absorption layer, a second semiconductor layer, an electrode layer and an electrode layer, wherein the substrate is arranged on the substrate, the induced crystal nucleus layer is arranged on the first semiconductor layer, the perovskite absorption layer covers the induced crystal nucleus layer and the first semiconductor layer, the second semiconductor layer is arranged on the perovskite absorption layer, the electrode layer is arranged on the second semiconductor layer, and the electrode layer is arranged on the second semiconductor layer.

The invention further provides a manufacturing method for manufacturing the perovskite solar cell. The method includes providing a substrate and forming a first semiconductor layer on the substrate, forming an induced nucleation layer on the first semiconductor layer, forming a perovskite absorption layer to cover the induced nucleation layer and the first semiconductor layer, forming a second semiconductor layer on the perovskite absorption layer, and forming an electrode layer on the second semiconductor layer.

In order to make the features and advantages of the embodiments of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

FIG. 1 is a schematic cross-sectional view of a perovskite solar cell structure according to some embodiments of the invention;

FIG. 2 is a top view of a perovskite solar cell structure according to some embodiments of the invention;

3A-3D are process flow diagrams of forming intermediate structures of a perovskite solar cell structure according to some embodiments of the invention;

FIGS. 4A-4B are process flow diagrams of forming intermediate structures of a perovskite solar cell structure according to some embodiments of the invention;

FIGS. 5A-5D are magnified views of perovskite absorption layers shown by optical microscopy, wherein FIGS. 5A, 5B are magnified views of perovskite absorption layers of comparative examples, and FIGS. 5C, 5D are magnified views of perovskite absorption layers of examples;

FIGS. 6A, 6B are magnified views of perovskite absorber layers of some embodiments of the invention as shown by scanning electron microscopy;

FIG. 7 is a graph showing the fluorescence spectra of the perovskite absorption layers of comparative example and example;

FIG. 8 is a graph of X-ray diffraction analysis spectra of perovskite absorption layers of comparative example and example; and FIG. 9 is a graph of cell open circuit voltage versus current density for the perovskite solar cell structures of comparative examples and examples.

[ description of reference ]

100 perovskite solar cell structure

110 substrate

120 first semiconductor layer

130 induced nucleation layer

130a crystal nucleus point

130b crystal nucleus point

140 perovskite absorption layer

150 second semiconductor layer

160 transparent conductive layer

170 electrode

180 precursor solution

210 crystal nucleus point

220 island structure

D diameter

P pitch

Detailed Description

The perovskite solar cell structure of some embodiments of the present invention is described in detail below. It is to be understood that the following description provides many different embodiments, or examples, for implementing different aspects of embodiments of the invention. The specific components and arrangements described below are simply for clarity and to describe some embodiments of the invention. These are, of course, merely examples and are not intended to be limiting. Moreover, repeated reference numerals or designations may be used in various embodiments. These iterations are merely provided for a simplified and clear description of some embodiments of the present invention, and are not intended to represent any correlation between the different embodiments and/or structures discussed. Furthermore, when a first material layer is located on or above a second material layer, the first material layer and the second material layer are in direct contact. Alternatively, one or more further layers of material may be provided, in which case there may not be direct contact between the first and second layers of material.

Furthermore, relative terms, such as "lower" or "bottom" and "upper" or "top," may be used in embodiments to describe one component's relative relationship to another component of the drawings. It will be understood that if the device of the drawings is turned upside down, components described as being on the "lower" side will be components on the "upper" side. As used herein, the term "about", "about" or "substantially" generally means within 20%, preferably within 10%, and more preferably within 5%, or within 3%, or within 2%, or within 1%, or within 0.5% of a given value or range. The amounts given herein are approximate, that is, the meanings of "about", "about" and "about" may be implied without specifically stating "about", "about" or "about".

Some embodiments of the present invention provide a perovskite solar cell structure. In some embodiments, the perovskite solar cell structure comprises an induced nucleation layer. The induced crystal nucleus layer can be used as a crystal seed to induce the perovskite absorption layer to nucleate at the bottom, so as to promote the perovskite crystal to grow from the bottom to the top and to the side surface. Therefore, the generation of crystal defects is reduced, the crystal quality of the perovskite absorption layer is improved, and the efficiency and the stability of the perovskite solar cell structure are improved.

Referring to fig. 1, fig. 1 is a schematic cross-sectional view of a calcium perovskite solar cell structure 100 according to some embodiments of the invention. As shown in fig. 1, the perovskite solar cell structure 100 comprises a substrate 110. The substrate 110 may be a transparent conductive substrate, such as a fluorine-doped Tin Oxide (FTO) substrate.

Furthermore, the perovskite solar cell structure 100 comprises a first semiconductor layer 120. The first semiconductor layer 120 is disposed on the substrate 110. The first semiconductor layer 120 contains fullerene or 2, 2 ', 7, 7' -tetrakis [ N, N-bis (4-methoxyphenyl) amino group]-9, 9 ' -spirobifluorene (2, 2 ', 7, 7 ' -Tetrakis [ N, N-di (4-methoxyphenyl) amino)]9, 9' -Spiro-bifluorene, Spiro-OMeTAD), fullerenes for example [6.6]-phenyl-C61-butyric acid methyl ester ([6, 6)]phenyl-C61-butyl acid methyl ester, PCBM). In addition, the first semiconductor layer 120 further includes nickel oxide (NiO) and titanium dioxide (TiO)₂) Carbon (C), tin dioxide (SnO)₂) Or other materials. In some embodiments, the first semiconductor layer 120 may be a p-type semiconductor layer or an n-type semiconductor layer.

In some embodiments, the perovskite solar cell structure comprises an induced nucleation layer 130 comprising a plurality of nucleation sites 130a (see also fig. 2). The nucleation sites 130a are disposed over a portion of the first semiconductor layer 120. In some embodiments, the nucleation sites 130a are hydrophobic materials. In some embodiments, the nucleation sites 130a are more hydrophobic relative to the first semiconductor layer 120. In some embodiments, induced nucleation layer 130 comprises indium tin oxide. Indium Tin Oxide (ITO), nickel Oxide (NiO), molybdenum sulfide (MoS)_X) Molybdenum oxide (MoO)_X) Tungsten oxide (WO)_X) Or other suitable material. The nucleation sites 130a are provided to help enable perovskite crystals to grow upward from the upper surface of the first semiconductor layer 120 during the formation of the perovskite absorption layer 140, and the perovskite absorption layer 140 formed in this manner has fewer crystal defects. With respect to the use of crystal nucleiThe detailed process of forming the perovskite absorption layer 140 by the dots 130a will be described later.

In some embodiments, the perovskite solar cell structure 100 comprises a perovskite absorption layer 140, the perovskite absorption layer 140 covering the nucleation site 130a and being formed over the first semiconductor layer 120. The general chemical structure of the perovskite absorption layer 140 is ABX₃. Wherein A may be selected from metal ions, for example from Li⁺、Na⁺、Cs⁺、Rb⁺、K⁺Any one of the group consisting of; alternatively, a may also contain 1 to 15 carbons and 1 to 20 heteroatoms, which may be N, O or S, for example a may be methylammonium, formamidine, hydroxylammonium, hydrazine, azonium, dimethylammonium, ethylammonium, guanidine, tetramethylammonium or thiazole. In some embodiments, a may comprise more than one of the above materials or a combination of the above materials.

B may comprise a metal ion, for example selected from Li⁺、Na⁺、Cs⁺、Rb⁺、K+、Ge²⁺、Sn2⁺、Mn²⁺、Fe²⁺、Co²⁺、Ni² ⁺、Pd2⁺、Pt²⁺、Cu2⁺、Zn²⁺、Cd²⁺、Hg²⁺、Be²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺、Eu²⁺、Tm²⁺、Yb²⁺Any one of the group consisting. In some embodiments, B may comprise more than one of the above materials or a combination of the above materials.

X is an anion, e.g. halogen, the halogen comprising Cl^-、Br^-、I^-. X may also comprise NCS^-、CN^-、NCO^-Or RCOO^-Wherein R may be methyl or ethyl. In some embodiments, X may comprise more than one of the above materials or a combination of the above materials.

In some embodiments, the perovskite absorption layer 140 may be formed by dissolving the compound comprising A, B and X in a solvent to form a precursor solution, and then coating the precursor solution on the nucleation site 130a and the first semiconductor layer 120, followed by evaporating the solvent. This process will be described in detail later.

The perovskite solar cell structure 100 comprises a second semiconductor layer 150. The second semiconductor layer 150 is disposed on the perovskite absorption layer 140. The second semiconductor layer 150 may include fullerene or 2, 2 ', 7, 7' -tetrakis [ N, N-bis (4-methoxyphenyl) amino]-9, 9 ' -spirobifluorene (2, 2 ', 7, 7 ' -Tetrakis [ N, N-di (4-methoxyphenyl) amino)]9, 9' -Spiro-bifluorene, Spiro-OMeTAD), fullerenes for example [6.6]-phenyl-C61-butyric acid methyl ester ([6, 6)]phenyl-C61-butyl acid methyl ester, PCBM). In addition, the second semiconductor layer 150 further includes NiO and TiO₂、C、SnO₂Or other materials. In some embodiments, the second semiconductor layer 150 may be a p-type semiconductor layer or an n-type semiconductor layer, and has a different conductivity type from the first conductor layer 120.

The perovskite solar cell structure 100 comprises a transparent conductive layer 160. The transparent conductive layer 160 is disposed on the second semiconductor layer 150. The transparent conductive layer 160 allows ambient light to be incident, and has an effect of scattering the incident light, so that the efficiency of light absorption is increased to improve the efficiency of photoelectric conversion. The transparent conductive layer 160 may be a single layer or a multi-layer structure. The material of the transparent conductive layer 160 includes Zinc Oxide, Tin Oxide, and the above-mentioned doping materials, such as fluorine-doped Tin Oxide (FTO), aluminum-doped Zinc Oxide (AZO), antimony-doped Tin Oxide (ATO), or other materials.

The perovskite solar cell structure 100 comprises an electrode 170. The electrode 170 is disposed on the transparent conductive layer 160. The transparent conductive layer 160 includes a metal material, such as silver (Ag), copper (Cu), aluminum (a1), molybdenum (Mo), tungsten (W), gold (Au), chromium (Cr), nickel (Ni), platinum (Pt), or titanium (Ti).

Sunlight can enter the internal structure of the perovskite solar cell structure 100 from the substrate 110, and electron holes are generated after photoelectric conversion through the first semiconductor layer 120, the second semiconductor layer 150 and the perovskite absorption layer 140, and then the electrode 170 can conduct current by providing a transfer loop.

Referring to fig. 2, fig. 2 is a top view of a perovskite solar cell structure 100 according to some embodiments of the invention. For clarity of description of the arrangement of the nucleation inducing layer 130, the nucleation sites 130a and the first semiconductor layer 120, other elements are omitted in fig. 2.

In some embodiments, the induced nucleation layer 130 may be a patterned layer, which includes a plurality of nucleation points 130a disposed on the first semiconductor layer 120 and exposing a portion of the first semiconductor layer 120, as viewed from the top view. Here, the patterned layer means a layer having a plurality of discontinuous blocks, the blocks may have any of the same shape or different shapes, the distances between the blocks may be the same or different, and the blocks may be arranged in any manner.

As shown in fig. 2, the plurality of nucleation points 130a are separated from each other and have a pitch P. In some embodiments, pitch P ranges between about 0.1mm and 1.7 mm. If the pitch is less than 0.1mm, transmittance is reduced, so that photocurrent is reduced, thereby reducing cell efficiency; if the spacing is greater than 1.7mm, the quality of the perovskite grains will be affected. In some embodiments the spacing is from 0.4mm to 1.5mm, from 0.5mm to 1.2mm, or from 0.6mm to 1.0 mm. In some embodiments, the diameter D of the nucleation sites 130a ranges from about 30 μm to about 100 μm, such as 40 μm to 80 μm or 50 μm to 70 μm. If the diameter D is less than 30 μm, the crystal growth space will be limited, thereby limiting the grain size; if the diameter D is larger than 100 μm, the precursor solution cannot uniformly cover the nucleation sites.

In some cases, if the induced crystal nucleus layer 130 is not patterned and substantially completely covers the first semiconductor layer 120, the precursor solution of the perovskite absorption layer 140 cannot be coated on the induced crystal nucleus layer 130 due to the hydrophobicity of the induced crystal nucleus layer 130, and thus the perovskite absorption layer 140 cannot be formed. Since the size of the crystal nuclei 130a affects the crystal size of the perovskite absorption layer 140, the diameter D of the crystal nuclei 130a ranges from 30 μm to 100 μm in consideration of the quality of the formed crystals and the efficiency of the perovskite solar cell structure 100.

Referring to fig. 3A-3D, fig. 3A-3D are process flow diagrams of forming an intermediate structure of a perovskite solar cell 100 according to some embodiments of the invention. In detail, fig. 3A-3D illustrate a process of forming the perovskite absorption layer 140 on the first semiconductor layer 120. In addition, the cross-sections shown in FIGS. 3A-3D may be cross-sections taken along line A-A' of FIG. 2, wherein the structure shown in FIG. 2 is a top view of the structure of FIG. 3A.

Referring to fig. 3A, in some embodiments, after forming the first semiconductor layer 120 on the substrate 110, a plurality of nucleation sites 130a are formed on the first semiconductor layer 120. The nucleation sites 130a can be formed by a patterning process, such as, but not limited to, evaporation, sputtering, photolithography (lithograph) process, screen printing, or other suitable processes. In some embodiments, a patterned shielding layer (not shown) is disposed on the first semiconductor layer 120, wherein the shielding layer has a plurality of openings exposing the surface of the first semiconductor layer 120. Next, a hydrophobic material is disposed on the first semiconductor layer 120 through the shielding layer, and then the shielding layer is removed to form a nucleation point 130 a. The nucleation points 130a shown in fig. 2 are disposed at positions corresponding to the openings of the shielding layers. By providing the patterned shielding layer, an induced nucleation layer 130 as shown in fig. 2 can be formed, which includes a plurality of nucleation sites 130 a. The shielding layer may comprise a metal shield or other patterned shield.

As shown in fig. 3B, the precursor solution 180 is coated on the nucleation sites 130a and the first semiconductor layer 120. In some embodiments, the precursor to be formed into the perovskite may be dissolved in a solvent to form precursor solution 180. The perovskite precursor may comprise a plurality of compounds, each compound comprising any one of the group consisting of A, B or X, as described above. The solvent may include gamma-Butyrolactone (GBL), Dimethylformamide (DMF), Dimethylsulfoxide (DMSO), Dimethylacetamide (DMAc), N-methylpyrrolidone (N-Methyl-2-pyrollidone, NMP), or other suitable solvents. In some embodiments, the precursor solution 180 may be coated on the nucleation sites 130a and the first semiconductor layer 120 through a coating process.

As shown in fig. 3C, after the precursor solution 180 is applied, the solvent is evaporated to crystallize the perovskite to form the perovskite absorption layer 140. The substrate 110 may be preheated to a temperature of about 300 c to facilitate solvent evaporation. Due to the hydrophobic nature of the nucleation sites 130a, the precursor solution 180 is repelled, causing the perovskite absorption layer 140 to begin to form from the bottom (or upper surface of the first semiconductor layer 120). When the perovskite absorption layer 140 grows from the bottom to the top and the side, it is helpful to completely volatilize the solvent, and form crystals with few defects and larger crystal grains. In some embodiments, the perovskite absorption layer 140 is in direct contact with the nucleation sites 130a and the first semiconductor layer 120.

In some cases, if the nucleation sites 130a are not used, the perovskite absorption layer may form crystals from the upper surface of the precursor solution, and the crystals are formed in the order from the upper surface to the bottom, in such a way that evaporation of the solvent is blocked, so that the solvent is easily remained in the perovskite absorption layer, so that the perovskite absorption layer has more crystal defects, for example, holes are formed in the absorption layer, so that the formed crystal grains are smaller, and the coverage rate of the perovskite absorption layer on the first semiconductor layer is lower.

After the solvent is substantially completely evaporated, a perovskite absorption layer 140 is formed on the surface of the first semiconductor layer 120, as shown in fig. 3D. As described above, the crystal nucleus points 130a can prevent the solvent from remaining on the upper surface of the first semiconductor layer 120 during the formation of the perovskite absorption layer 140 to cause defects in the crystals of the perovskite absorption layer 140, and thus the provision of the crystal nucleus points 130a facilitates the formation of the perovskite absorption layer 140 having larger crystal grains and provides a higher coverage of the perovskite absorption layer 140 over the first semiconductor layer 120. The larger the crystal grain size of the perovskite absorption layer 140, the more the stability of the perovskite absorption layer 140 is improved, so that the perovskite solar cell structure 100 can be used for a long time and maintain high efficiency.

Referring to fig. 4A-4B, fig. 4A-4B are process flow diagrams of forming intermediate structures of a perovskite solar cell structure 100 according to some embodiments of the invention. Referring to fig. 4A, in some embodiments, the nucleation site 130b may be formed on the first semiconductor layer 120 prior to forming the perovskite absorption layer 140. The nucleation points 130b may be formed by performing a modification process on the surface of the first semiconductor layer 120, for example, performing a hydrophobic treatment on the surface of the first semiconductor layer 120. In some embodiments, the surface of the first semiconductor layer 120 may be plasma-treated to form radicals or hydrophobic functional groups on the surface of the first semiconductor layer 120 to form the nucleation sites 130 b.

In this embodiment, the nucleation points 130b are embedded in the first semiconductor layer 120, and the upper surfaces of the nucleation points 130b and the first semiconductor layer 120 are substantially coplanar. In this embodiment, the nucleation sites 130b are a hydrophobic semiconductor material.

After the formation of the nucleation sites 130B, a perovskite absorption layer 140 is formed on the first semiconductor layer 120, as shown in fig. 4B. The process from fig. 4A to 4B is the same as or similar to the process from fig. 3A to 3D, and the description thereof will not be repeated. In this embodiment, the patterned nucleation inducing layer 130 may be composed of a plurality of nucleation points 130 b. In addition, the material of the induced nucleation layer 130 of this embodiment is the same as or similar to that of the first semiconductor layer 120.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below:

example 1

An FTO substrate was prepared, ultrasonically cleaned with isopropyl alcohol (IPA), and then dried with nitrogen gas. Next, a solution containing NiO nanoparticles was coated on an FTO substrate by spin coating, and a NiO thin film was prepared in an environment at a temperature of 300 ℃, wherein the thickness of the NiO thin film was about 60nm, and then a patterned metal mask was disposed on the NiO thin film/FTO substrate, an induced nucleation layer having a plurality of nucleation points was formed on the NiO thin film by a sputtering process, and the metal mask was removed, wherein the diameter of each nucleation point was about 50 μm, and the interval between the nucleation points was about 1.0 mm. Next, a precursor solution for forming a perovskite absorption layer, which contains methylaminonium lead iodide (CH), is prepared₃NH₃PbI₃MAPbI for short₃) Gamma-butyrolactone and diMethyl sulfoxide of which MAPbI₃Can use PbI₂MAI ratio of 1: 1, DMSO/GBL ratio of 3: 7, and MAPbI in the final precursor solution₃At a concentration of 1.2M (MAPbI)₃V (DMSO + GBL) ═ 1.2M). And spin-coating the precursor solution on the heated induced crystal nucleus layer/NiO film/FTO substrate, and forming a perovskite absorption layer after the solvent is evaporated. Next, an n-type PCBM film was fabricated by spin coating, wherein the thickness of the PCBM film was about 50 nm. Next, a silver electrode was fabricated by evaporation on the PCBM thin film, wherein the thickness of the silver electrode was about 150nm, to complete the perovskite solar cell structure of example 1.

Comparative example 1

An FTO substrate was prepared, cleaned with IPA by ultrasonic waves, and then dried with nitrogen gas. Next, a solution containing NiO nanoparticles was coated on the FTO substrate by spin coating, and a NiO thin film was prepared in an environment at a temperature of 300 ℃, wherein the thickness of the NiO thin film was about 60 nm. Next, a precursor solution for forming a perovskite absorption layer, which contains lead methylaminoiodide (MAPbI), is prepared₃) Gamma-butyrolactone and dimethyl sulfoxide. And spin-coating the precursor solution on the heated induced nucleation layer/NiO film/FTO substrate by a spin coating method, and forming a perovskite absorption layer after the solvent is evaporated. Next, an n-type PCBM film was fabricated by spin coating, wherein the thickness of the PCBM film was about 50 nm. Next, a silver electrode was fabricated by evaporation on the PCBM thin film, wherein the thickness of the silver electrode was about 150nm, to complete the perovskite solar cell structure of comparative example 1.

Referring to fig. 5A-5D, fig. 5A-5D are magnified views of the perovskite absorption layer shown by an optical microscope, wherein fig. 5A, 5B are magnified views of the perovskite absorption layer of comparative example 1, fig. 5C, 5D are magnified views of the perovskite absorption layer of example 1, fig. 5A, 5C are magnified views of 5 times, and fig. 5B, 5D are magnified views of 50 times.

Comparing FIGS. 5A and 5C, it can be seen that FIG. 5C has a plurality of dots of lighter color, about 1.0mm pitch, and about 100 μm size, the positions of which correspond to the locations where the nucleation sites 210 (shown in FIG. 5D) are formed. As shown in fig. 5C, the perovskite absorption layer within the dots is lighter in color than elsewhere due to the smoother surface of the perovskite absorption layer grown on the crystal nuclei 210. On the other hand, the perovskite absorption layer formed outside the crystal nucleus points 210 is darker in color, and represents a rough surface.

Comparing fig. 5B and 5D, a plurality of darker island structures 220 can be found in fig. 5B. In addition, it can be seen from fig. 5D that there are also a plurality of island structures 220 located outside the dots. The length of the island structures 220 ranges from about 5 μm to about 10 μm. The island structures 220 are the result of pores formed within the perovskite absorber layer. In contrast, it can be seen in fig. 5D that the surface of the perovskite absorption layer on and around the nucleation site 210 is relatively smooth, i.e., the surface of the perovskite absorption layer formed on the induced nucleation layer is relatively free of pores, so that the surface is relatively dense. Since comparative example 1 does not form the induced nucleation layer or the nucleation sites 210, the island structures 220 of the perovskite absorption layer are distributed throughout the perovskite absorption layer, so that the coverage of the perovskite absorption layer is poor. In example 1, the induced nucleation layer is formed, and as is clear from fig. 5D, the perovskite absorption layer on and around the nucleation sites 210 does not substantially contain the island-like structures 220, so that the coverage of the perovskite absorption layer formed on and around the nucleation sites 210 is preferable. The island structures 220 reduce light absorption and reduce short circuit current. In addition, the island-shaped structure 220 may cause crystal defects, which may reduce the open-circuit voltage and fill factor, thereby reducing the efficiency of the battery. Accordingly, by providing the induced nucleation layer, the generation of crystal defects can be reduced, a better film quality can be provided, and the problems derived from the generation of the island-shaped structures 220 can be avoided.

In some embodiments, the diameter of the crystalline grains of the perovskite absorption layer formed on the crystal nucleation sites 210 is in the range of about 20 μm to about 40 μm. And the size of crystal grains of the perovskite absorption layer formed outside the crystal nucleus points 210 and surrounding the crystal nucleus points 210 is in the range of about 0.5 μm to about 1 μm. That is, the perovskite absorption layer formed on the induced nucleation layer has larger grains. In some embodiments, the ratio of the size of the crystalline grains of the perovskite absorption layer above the crystal nucleation sites 210 to the size of the crystalline grains of the perovskite absorption layer outside the crystal nucleation sites 210 is between about 20: 1 and about 40: 1.

From the above, the perovskite absorption layer may be divided into a first region and a second region. The first region is substantially directly above the induced nucleation layer, the perovskite absorption layer of the second region is free of the induced nucleation layer or the nucleation sites, and the second region surrounds and is in contact with the first region. The diameter of the crystal grains of the perovskite absorption layer positioned in the first region is larger than that of the crystal grains of the perovskite absorption layer positioned in the second region. In some embodiments, the ratio of the crystal diameter of the first zone to the second zone is from 20: 1 to 40: 1. The area of the first region projected to the FTO substrate can be larger than or equal to the area of the crystal nucleus point projected to the FTO substrate. For example, the ratio of the projected area of the first region to the projected area of the nucleation sites is in the range of about 1: 1 to about 2: 1. Furthermore, the first region overlaps the induced nucleation layer or the nucleation sites, as seen in a top view.

Referring to fig. 6A, 6B, fig. 6A, 6B are enlarged views of the perovskite absorption layer of example 1 shown by a scanning electron microscope. The magnification of fig. 6A is 500 times, and the magnification of fig. 6B is 5000 times. It can be seen from fig. 6B that the crystals of the perovskite absorption layer located within the dots 210 have a dendritic structure. Since the interface between the induced nucleus layer and the precursor solution is hydrophobic, unfavorable perovskite crystals are precipitated. As the solvent evaporates, it may oversaturate the solution and cause rapid growth of the perovskite crystals. The crystal of the perovskite absorption layer positioned on the induced crystal nucleus layer is in a dendritic structure due to the fact that the growth speed of the crystal is too fast. The crystal grain size of the dendrite can be adjusted by controlling the temperature of the FTO substrate. In some embodiments, the dendrite has a grain size in the range of about 20um to 40 um.

Referring to fig. 7, fig. 7 is a raman spectrum of the perovskite absorption layer of comparative example 1 and example 1. Wherein the solid line is the spectrum of example 1 and the dashed line is the spectrum of comparative example 1. The analysis light source is a laser with the wavelength of 532nm, the laser spot is about 10um, and the analysis range is from 50cm^-1～650cm^-1Resolution of 0.6cm^-1. The results show that the wave number of the comparative example 1 and the example 1 is 76.8em^-1、93.5cm^-1、107.7em^-1、163.0cm^-1And 214.2cm^-1Has a peak value of 76.8cm^-1、93.5cm^-1、107.7cm^-1Compliance with MAPbI₃And 163.0cm^-1And 214.2cm^-1Then it meets PbI₂Peak value of (a). From the peak intensity, it can be seen that PbI of the perovskite absorption layer of example 1₂/MAPbI₃The signal intensity ratio of (A) is significantly lower than that of PbI of comparative example 1₂/MAPbI₃The results show that it is easier to react the precursor into MAPbI by using an induced nucleation layer₃Thus unreacted PbI₂The amount of residual (c) was small as compared with comparative example 1.

Referring to fig. 8, fig. 8 is an X-ray diffraction analysis (XRD) spectrum of the perovskite absorption layers of comparative example 1 and example 1. Wherein the solid line is the spectrum of example 1 and the dashed line is the spectrum of comparative example 1. As can be seen from FIG. 8, there are significant diffraction peaks at 13.98 °, 19.86 °, 28.34 °, 31.82 °, 40.50 ° and 43.14 °, which correspond to MAPbI₃Referring to tables 1 and 2, the following are shown:

TABLE 1

2 theta/signal strength	Comparative example 1	Example 1	Example 1/comparative example 1
				13.98	61	87	0.7
19.86	23	61	0.38
				28.34	26	53	0.49
31.82	54	80	0.68
				40.5	25	45	0.56
43.14	26	43	0.6

TABLE 2

2 theta/full width at half maximum	Comparative example 1	Example 1
			13.98	1.13	0.41
31.82	0.47	0.41

Table 1 shows the signal intensities at peaks of 13.98 °, 19.86 °, 28.34 °, 31.82 °, 40.50 ° and 43.14 ° for comparative example 1 and example 1, and table 2 shows the full width at Half Maximum (FWHM) analysis of the two diffraction peaks with the strongest signal intensities, 13.98 ° and 31.82 °. As is clear from fig. 8, table 1 and table 2, the signal intensities of all diffraction peaks of the perovskite of example 1 are greater than those of the perovskite of comparative example 1. Table 2 shows that the full widths at half maximum of comparative example 1 and example 1 at 13.98 ° are 1.13 and 0.41, respectively, and the full widths at half maximum of 31.82 ° are 0.47 and 0.41, respectively. The smaller the value of the full width at half maximum, the better the quality of the crystal. From the analysis results in table two, it can be seen that the crystal quality of the perovskite absorption layer grown in example 1 is superior to that of the perovskite absorption layer prepared in comparative example 1.

FIG. 9 shows the Open-cell Voltage (V) of the perovskite solar cell structures of comparative example 1 and example 1_on) Graph with current density. The open Circuit voltage of the battery of example 1 was 1.056V, and the Short Circuit Current Density (J)_sc) Is 19.76mA/cm²The Fill Factor (Fill-Factor, F.F.) was 66.29% and the efficiency was 13.83%, with the solid line being example 1 and the dashed line being comparative example 1. The open circuit voltage of the battery of comparative example 1 was 1.052V, and the short circuit current density was 18.59mA/cm²The fill factor was 64.64% and the efficiency was 12.64%. According to fig. 9, the cell efficiency of the perovskite solar cell structure of example 1 is higher than that of the perovskite solar cell structure of comparative example 1, and the main reason is attributable to the higher coverage of the perovskite absorption layer formed using the induced nucleation layer, thus increasing the current density. Furthermore, the perovskite absorption layer formed by using the induced crystal nucleus layer has high crystal qualityAnd the defects are relatively few, so that the battery efficiency can be improved. In addition, see table 3, as follows:

TABLE 3

	V_OC(V)	J_sc(mA/cm²)	F.F.(％)	Eff.(％)
					No crystal nucleus point	1.064	18.27	75.16	14.61
The spacing between crystal nucleus points is 0.6mm	1.077	18.58	75.97	15.21
					The spacing between crystal nucleus points is 1.0mm	1.078	18.63	75.96	15.26

Table 3 sets forth a comparison table of open circuit voltage, short circuit current density, fill factor and efficiency for the points where no nucleation occurred and the spacing between the points was 0.6mm and 1.0mm, respectively. It can be seen from the table that when the spacing between nucleation sites is greater than 0.6mm, the open-circuit voltage, the short-circuit current density, the fill factor and the efficiency can be further improved than those of the nucleation sites.

Although embodiments of the present invention and their advantages have been disclosed above, it should be understood that various changes, substitutions and alterations can be made herein by those skilled in the art without departing from the spirit and scope of the invention. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification, but rather, the process, machine, manufacture, composition of matter, means, methods and steps described in connection with the embodiments disclosed herein will be understood to one skilled in the art from the disclosure to which the present application relates, and will readily suggest themselves to those of ordinary skill in the art that the present application may be practiced without these specific details. Accordingly, the scope of the present application includes the processes, machines, manufacture, compositions of matter, means, methods, and steps described in the specification. In addition, each claim constitutes an individual embodiment, and the scope of protection of the present invention also includes combinations of the respective claims and embodiments.

Claims

1. A perovskite solar cell comprising:

a substrate;

a first semiconductor layer disposed on the substrate;

an induced nucleation layer disposed on the first semiconductor layer;

a perovskite absorption layer covering the induced crystal nucleus layer and the first semiconductor layer;

the second semiconductor layer is arranged on the perovskite absorption layer; and

an electrode layer disposed on the second semiconductor layer.

2. The perovskite solar cell of claim 1, wherein the induced nucleation layer is a patterned layer.

3. The perovskite solar cell of claim 1, wherein the induced nucleation layer is a hydrophobic layer.

4. The perovskite solar cell of claim 1, wherein the material of the induced nucleation layer comprises indium tin oxide, nickel oxide, molybdenum sulfide, molybdenum oxide, or tungsten oxide.

5. The perovskite solar cell of claim 1, wherein the induced nucleation layer comprises a plurality of nucleation sites having a diameter in a range of 30 μ ι η to 100 μ ι η.

6. The perovskite solar cell of claim 5, wherein the spacing of the nucleation sites is in the range of 0.1mm to 1.7 mm.

7. The perovskite solar cell of claim 5, wherein the spacing of the nucleation sites is in the range of 0.4mm to 1.5 mm.

8. The perovskite solar cell of claim 1, wherein the induced nucleation layer is embedded in the first semiconductor layer and the induced nucleation layer comprises a hydrophobic semiconductor material.

9. The perovskite solar cell of claim 1, wherein the perovskite absorption layer comprises a first region directly above the induced nucleation layer and a second region surrounding and in contact with the first region, the ratio of the grain diameter in the first region to the grain diameter in the second region being from 20: 1 to 40: 1.

10. The perovskite solar cell of claim 9, wherein the diameter of the crystalline grains located within the first region is in a range of 20 μ ι η to 40 μ ι η.

11. The perovskite solar cell of claim 1, wherein the perovskite absorption layer comprises dendritic structured crystals.

12. A method of fabricating a perovskite solar cell, comprising:

providing a substrate;

forming a first semiconductor layer on the substrate;

forming an induced nucleation layer on the first semiconductor layer;

forming a perovskite absorption layer to cover the induced crystal nucleus layer and the first semiconductor layer;

forming a second semiconductor layer on the perovskite absorption layer; and

forming an electrode layer on the second semiconductor layer.

13. The method of claim 12, further comprising:

the induced nucleation layer is patterned to form a plurality of spaced apart nucleation sites.

14. The method of claim 12, wherein the nucleation inducing layer is a hydrophobic layer.

15. The method of claim 12, wherein the material of the nucleation inducing layer comprises indium tin oxide, nickel oxide, molybdenum sulfide, molybdenum oxide, or tungsten oxide.

16. The method of claim 12, further comprising:

performing a hydrophobization process on the first semiconductor layer to form the induced nucleation layer.