Method for improving stability of perovskite absorption layer

Abstract

The invention provides a method for improving the stability of a perovskite absorption layer, and belongs to the technical field of perovskite solar cells. According to the method, oxygen partial pressure is regulated and controlled in the process of vapor deposition of the metal oxide charge transport layer, heat preservation temperature and heat preservation time are regulated and controlled in annealing treatment of the metal oxide charge transport layer, or ascorbic acid is added into a precursor solution of the metal oxide charge transport layer, and then the metal oxide charge transport layer is obtained through coating. According to the perovskite cell, the electronegativity of metal ions in the metal oxide charge transport layer can be improved, so that metal Pb in the perovskite transport layer can be oxidized to a certain extent, iodine in the perovskite transport layer is reduced, stabilization of a perovskite absorption layer in the perovskite cell is realized, and carrier scattering of a perovskite interface is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of perovskite solar cells, and in particular relates to a method for improving the stability of a perovskite absorption layer. Background Art

[0002] Perovskite solar cells are a revolutionary new photovoltaic technology, selected by the US magazine Science as one of the top ten global technological breakthroughs in 2013. They have the characteristics and advantages of high efficiency, low cost, and can be prepared by low-temperature solution method. After just over a decade of development, perovskite solar cells have become the hottest branch of next-generation photovoltaic technology, attracting great attention and R&D investment from domestic and foreign academic and industrial circles.

[0003] Perovskite absorber layer CH 3 NH 3 PbI 3 It is the core absorption layer of perovskite solar cells. At present, interstitial iodine and lead precipitation (i.e. precipitated iodine and lead elements, existing in the interstitial position of the crystal structure) is the most critical defect type in perovskite solar cells, which greatly limits the efficiency and stability of perovskite solar cells. Interstitial iodine and lead precipitation may occur during the processing of solutions, films and devices, and interstitial iodine and lead precipitation will further accelerate the decomposition of perovskite crystals.

[0004] In view of this, it is urgent to design a method to improve the stability of the perovskite absorber layer. Summary of the invention

[0005] The present invention is based on the inventors' discovery and understanding of the following facts and problems: since the metal oxide charge transport layer and the perovskite absorption layer are in contact with each other, the inventors found that by optimizing the metal oxide charge transport layer during the preparation process of the metal oxide charge transport layer, the obtained metal oxide charge transport layer can improve the stability of the perovskite absorption layer prepared previously or later.

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an embodiment of the present invention provides a method for improving the stability of a perovskite absorption layer.

[0007] A first aspect of an embodiment of the present invention provides a method for improving the stability of a perovskite absorption layer, wherein the method satisfies at least one of the following conditions:

[0008] During the vapor deposition of the metal oxide charge transport layer, the oxygen partial pressure in the furnace atmosphere is controlled, wherein the volume fraction of oxygen in the furnace atmosphere is less than 6%;

[0009] After the metal oxide charge transport layer is obtained by vapor deposition, the metal oxide charge transport layer is annealed, the annealing temperature is 200-300° C., and / or the annealing time is 5-600 min.

[0010] The advantages and technical effects brought by the method of the first aspect of the embodiment of the present invention are:

[0011] When the metal oxide charge transport layer of the perovskite battery is prepared by the vapor deposition method, the electronegativity of the metal ions in the metal oxide charge transport layer can be improved by regulating the oxygen partial pressure during the vapor deposition of the metal oxide charge transport layer and regulating the holding temperature and holding time during the annealing treatment of the metal oxide charge transport layer. This can oxidize the metal Pb in the perovskite transport layer to a certain extent and reduce the iodine in the perovskite transport layer, thereby achieving the stabilization of the perovskite absorption layer in the perovskite battery and reducing the carrier scattering at the perovskite interface.

[0012] In some embodiments, during the vapor deposition of the metal oxide charge transport layer, the oxygen partial pressure in the furnace atmosphere is controlled, and the volume fraction of oxygen in the furnace atmosphere is less than 4%.

[0013] In some embodiments, the annealing treatment is carried out at a holding temperature of 270-300°C.

[0014] In some embodiments, the annealing treatment has a holding time of 30 to 60 minutes.

[0015] A second aspect of an embodiment of the present invention provides a method for improving the stability of a perovskite absorption layer, comprising the following steps: coating a metal oxide charge transport layer precursor solution on a substrate, and obtaining a metal oxide charge transport layer after drying, wherein the metal oxide charge transport layer precursor solution contains ascorbic acid.

[0016] The advantages and technical effects brought by the method of the second aspect of the embodiment of the present invention are:

[0017] When the metal oxide charge transport layer of the perovskite battery is prepared by a coating method, ascorbic acid is added to the metal oxide charge transport layer precursor solution and then coated to obtain the metal oxide charge transport layer. In this process, the presence of ascorbic acid can increase the electronegativity of the metal ions in the metal oxide charge transport layer, thereby oxidizing the metal Pb in the perovskite transport layer to a certain extent and reducing the iodine in the perovskite transport layer, thereby achieving the stabilization of the perovskite absorption layer in the perovskite battery and reducing the carrier scattering at the perovskite interface.

[0018] In some embodiments, in the metal oxide charge transport layer precursor solution, the mass concentration of ascorbic acid is 0.1-15%.

[0019] In some embodiments, in the metal oxide charge transport layer precursor solution, the mass concentration of ascorbic acid is 5-15%.

[0020] In some embodiments, in the metal oxide charge transport layer precursor solution, the mass concentration of ascorbic acid is 10-15%. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0022] A first aspect of an embodiment of the present invention provides a method for improving the stability of a perovskite absorption layer, wherein the method satisfies at least one of the following conditions:

[0023] During the vapor deposition of the metal oxide charge transport layer, the oxygen partial pressure in the furnace atmosphere is controlled, wherein the volume fraction of oxygen in the furnace atmosphere is less than 6%;

[0024] After the metal oxide charge transport layer is obtained by vapor deposition, the metal oxide charge transport layer is annealed, the annealing temperature is 200-300° C., and / or the annealing time is 5-600 min.

[0025] Working principle: The method of the embodiment of the present invention is to deposit a metal oxide charge transport layer (such as NiO) in the vapor phase. x ) process, and regulating the holding temperature and / or shortening the holding time during the annealing of the metal oxide charge transport layer, which helps to form metal ions with low oxidation valence (such as Ni 2+ ), while metal ions with high oxidation valence (such as Ni 3+ ) ratio is low, which increases the electronegativity of metal ions in the metal oxide charge transport layer, thereby oxidizing the metal Pb in the perovskite transport layer to a certain extent (Pb → Pb 2+ ), while reducing I in the perovskite transport layer 2 (I 2 →2I - ), to achieve the stabilization of the perovskite absorption layer in the perovskite battery and to reduce the carrier scattering at the perovskite interface.

[0026] It should be noted that the metal oxide charge transport layer in the method of the embodiment of the present invention can be a metal oxide electron transport layer or a metal oxide hole transport layer. The metal oxide electron transport layer can be treated by the method of the embodiment of the present invention, and / or the metal oxide hole transport layer can be treated by the method of the embodiment of the present invention. In addition, depending on the specific type of the metal oxide charge transport layer and the difference in the positive or inverted structure of the perovskite battery, the preparation order of the metal oxide charge transport layer and the perovskite absorption layer is also different, and adaptive adjustment is required.

[0027] In the method of the embodiment of the present invention, during the vapor deposition of the metal oxide charge transport layer, the oxygen partial pressure in the furnace atmosphere is controlled, and the volume fraction of oxygen in the furnace atmosphere is less than 6%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, etc. When the oxygen partial pressure is too high, it is not conducive to the formation of metal ions with low oxidation valence states (such as Ni 2+ ), which is not conducive to improving the electronegativity of metal ions in the metal oxide charge transport layer, and ultimately is not conducive to improving the stability of the perovskite absorption layer in the perovskite battery. Preferably, in some embodiments, during the vapor deposition of the metal oxide charge transport layer, the volume fraction of oxygen in the furnace atmosphere is less than 4%.

[0028] In some embodiments, the furnace atmosphere is a mixture of oxygen and an inert gas, and the inert gas may be nitrogen and / or argon.

[0029] In the method of the embodiment of the present invention, the holding temperature of the annealing treatment is 200-300°C, such as 200°C, 220°C, 250°C, 270°C, 290°C, 300°C, etc. When the holding temperature of the annealing treatment is lower than 200°C, the oxidation state of the metal oxide cannot achieve the desired effect and is unstable. When the holding temperature of the annealing treatment is higher than 300°C, it is not conducive to the formation of metal ions with low oxidation valence states (such as Ni 2+ ), which is not conducive to improving the electronegativity of metal ions in the metal oxide charge transport layer, and ultimately not conducive to improving the stability of the perovskite absorption layer in the perovskite battery. Preferably, in some embodiments, the holding temperature of the annealing treatment is 270-300°C.

[0030] In the method of the embodiment of the present invention, the holding time of the annealing treatment is 5 to 600 minutes, for example, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 45 minutes, 60 minutes, 90 minutes, 100 minutes, 200 minutes, 300 minutes, 400 minutes, 500 minutes, 600 minutes, etc. When the holding time of the annealing treatment is greater than 600 minutes, it is not conducive to the formation of metal ions with low oxidation valence states (such as Ni 2+ ), which is not conducive to improving the electronegativity of metal ions in the metal oxide charge transport layer, and ultimately not conducive to improving the stability of the perovskite absorption layer in the perovskite battery. Preferably, in some embodiments, the holding time of the annealing treatment is 30 to 60 minutes.

[0031] A second aspect of an embodiment of the present invention provides a method for improving the stability of a perovskite absorption layer, comprising the following steps: coating a metal oxide charge transport layer precursor solution on a substrate, and obtaining a metal oxide charge transport layer after drying, wherein the metal oxide charge transport layer precursor solution contains ascorbic acid.

[0032] Working principle: When the metal oxide charge transport layer of the perovskite battery is prepared by a coating method, the prior art directly coats a metal oxide charge transport layer precursor solution that does not contain ascorbic acid on the substrate.

[0033] In the method of the embodiment of the present invention, by adding ascorbic acid to the metal oxide charge transport layer precursor solution, during the preparation process of the metal oxide charge transport layer (such as SnOx), the presence of ascorbic acid makes the metal oxide charge transport layer precursor solution weakly acidic, and the weakly acidic environment helps the metal oxide charge transport layer to form metal ions with low oxidation valence (such as Sn 2+ ), while metal ions with high oxidation valence (such as Sn 4+ ) is low, which increases the electronegativity of metal ions in the metal oxide charge transport layer, and can oxidize the metal Pb in the perovskite transport layer to a certain extent (Pb → Pb 2+ ), while reducing I in the perovskite transport layer 2 (I 2 →2I - ), to achieve the stabilization of the perovskite absorption layer in the perovskite battery and to reduce the carrier scattering at the perovskite interface.

[0034] It should be noted that during the coating and drying process, ascorbic acid will evaporate with the solvent and will not remain in the perovskite solar cell.

[0035] In some embodiments, in the metal oxide charge transport layer precursor solution, the mass concentration of ascorbic acid is 0.1-15%, for example 0.1%, 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 15%, etc.

[0036] When the mass concentration of the ascorbic acid in the metal oxide charge transport layer precursor solution is too low, it is not conducive to forming an acidic environment, thereby being not conducive to the formation of metal ions with low oxidation valence states (such as Sn 2+ ), which is not conducive to improving the electronegativity of metal ions in the metal oxide charge transport layer, and ultimately is not conducive to improving the stability of the perovskite absorption layer in the perovskite battery. In some embodiments, in the metal oxide charge transport layer precursor solution, the mass concentration of ascorbic acid is 5-15%, for example, 5%, 6%, 8%, 10%, 12%, 14%, 15%, etc. In some embodiments, in the metal oxide charge transport layer precursor solution, the mass concentration of ascorbic acid is 10-15%, for example, 10%, 12%, 14%, 15%, etc.

[0037] The present invention is described in detail below with reference to embodiments.

[0038] Example 1

[0039] (1) A NiOx charge transport layer was magnetron sputtered on the FTO conductive glass. During the magnetron sputtering process, the oxygen flow rate was 2 sccm and the nitrogen flow rate was 80 sccm. The NiOx charge transport layer was then annealed. The annealing temperature was 270°C and the insulation time was 60 min.

[0040] (2) Preparation of CH on NiOx charge transport layer 3 NH 3 PbI 3 Perovskite absorber layer.

[0041] (3) In CH 3 NH 3 PbI 3 The spiro-OmetaD hole transport layer is prepared on the perovskite absorption layer.

[0042] (4) Prepare Au electrode on the spiro-OmetaD hole transport layer to obtain a perovskite solar cell.

[0043] Example 2

[0044] (1) A NiOx charge transport layer was magnetron sputtered on the FTO conductive glass. During the magnetron sputtering process, the oxygen flow rate was 3 sccm and the nitrogen flow rate was 80 sccm. The NiOx charge transport layer was then annealed. The annealing temperature was 270°C and the insulation time was 30 min.

[0045] (2) Preparation of CH on NiOx charge transport layer 3 NH 3 PbI 3 Perovskite absorber layer.

[0046] (3) In CH 3 NH 3 PbI 3 The spiro-OmetaD hole transport layer is prepared on the perovskite absorption layer.

[0047] (4) Prepare Au electrode on the spiro-OmetaD hole transport layer to obtain a perovskite solar cell.

[0048] Example 3

[0049] (1) A NiOx charge transport layer was magnetron sputtered on the FTO conductive glass. During the magnetron sputtering process, the oxygen flow rate was 3 sccm and the nitrogen flow rate was 80 sccm. The NiOx charge transport layer was then annealed. The annealing temperature was 300°C and the insulation time was 60 min.

[0050] (2) Preparation of CH on NiOx charge transport layer 3 NH 3 PbI 3 Perovskite absorber layer.

[0051] (3) In CH 3 NH 3 PbI 3 The spiro-OmetaD hole transport layer is prepared on the perovskite absorption layer.

[0052] (4) Prepare Au electrode on the spiro-OmetaD hole transport layer to obtain a perovskite solar cell.

[0053] Example 4

[0054] (1) A SnOx charge transport layer precursor solution is coated on FTO conductive glass to form a film and then dry to obtain a SnOx charge transport layer, wherein the mass concentration of ascorbic acid in the SnOx charge transport layer precursor solution is 10%.

[0055] (2) Preparation of CH on SnOx charge transport layer 3 NH 3 PbI3 Perovskite absorber layer.

[0056] (3) In CH 3 NH 3 PbI 3 The spiro-OmetaD hole transport layer is prepared on the perovskite absorption layer.

[0057] (4) Prepare Au electrode on the spiro-OmetaD hole transport layer to obtain a perovskite solar cell.

[0058] Comparative Example 1

[0059] The comparative example is the same as Example 1, except that the oxygen flow rate is 8 sccm.

[0060] Comparative Example 2

[0061] This comparative example is the same as Example 2, except that the holding time of the annealing treatment is 650 min.

[0062] Comparative Example 3

[0063] This comparative example is the same as Example 3, except that the holding temperature of the annealing treatment is 350°C.

[0064] Comparative Example 4

[0065] This comparative example is the same as Example 4, except that the SnOx charge transport layer precursor solution does not contain ascorbic acid.

[0066] The photoelectric conversion efficiency of the perovskite solar cells of Examples 1 to 4 and Comparative Examples 1 to 4 was tested, and the test results are shown in Table 1.

[0067] Table 1. Photoelectric conversion efficiency of perovskite solar cells of Examples 1 to 4 and Comparative Examples 1 to 4

[0068]

[0069]

[0070] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0071] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for improving the stability of a perovskite absorption layer, characterized in that: At least one of the following conditions is met: During the vapor deposition of the metal oxide charge transport layer, the oxygen partial pressure in the furnace atmosphere is controlled, wherein the volume fraction of oxygen in the furnace atmosphere is less than 6%; After the metal oxide charge transport layer is obtained by vapor deposition, the metal oxide charge transport layer is annealed, the annealing temperature is 200-300° C., and / or the annealing time is 5-600 min.

2. The method according to claim 1, characterized in that During the vapor deposition of the metal oxide charge transport layer, the oxygen partial pressure in the furnace atmosphere is controlled, and the volume fraction of oxygen in the furnace atmosphere is less than 4%.

3. The method according to claim 1 or 2, characterized in that: The holding temperature of the annealing treatment is 270-300°C.

4. The method according to claim 1 or 2, characterized in that: The holding time of the annealing treatment is 30 to 60 minutes.

5. A method for improving the stability of a perovskite absorption layer, characterized in that: The following steps are involved: A metal oxide charge transport layer precursor solution is coated on a substrate and dried to obtain a metal oxide charge transport layer, wherein the metal oxide charge transport layer precursor solution contains ascorbic acid.

6. The method according to claim 5, characterized in that In the metal oxide charge transport layer precursor solution, the mass concentration of ascorbic acid is 0.1-15%.

7. The method according to claim 6, characterized in that In the metal oxide charge transport layer precursor solution, the mass concentration of ascorbic acid is 5-15%.

8. The method according to claim 5, characterized in that In the metal oxide charge transport layer precursor solution, the mass concentration of ascorbic acid is 10-15%.

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