Perovskite gradient annealing process and cell thereof

Abstract

The invention relates to the technical field of solar photovoltaics, and particularly discloses a perovskite gradient annealing process and a cell thereof. The perovskite gradient annealing process comprises the following steps: annealing: heating the upper and lower sides or one side of a perovskite thin film substrate to a preset temperature, and carrying out heat preservation; different preset temperatures are set for the upper side and the lower side of the perovskite thin film substrate, so that the upper side and the lower side of the perovskite thin film substrate generate a temperature difference in the heat preservation stage; the temperature difference direction of the upper side and the lower side of the perovskite thin film substrate in the heat preservation stage is opposite to the temperature difference direction of the previous annealing by adjusting the preset temperature from the second annealing; wherein the temperature difference of the first annealing is greater than or equal to the temperature difference of the subsequent annealing. According to the scheme, an alternate gradient annealing mode is adopted, so that the prepared perovskite cell has higher photoelectric conversion efficiency; meanwhile, according to the annealing process provided by the scheme, the annealing temperature and the annealing time can be flexibly adjusted, efficient utilization of resources is achieved, and energy consumption is effectively reduced.

Description

Technical Field

[0001] The present application relates to the field of solar photovoltaic technology, and in particular to a perovskite gradient annealing process and a cell thereof. Background Art

[0002] As the global demand for clean energy continues to grow, the development and utilization of solar energy as an inexhaustible renewable energy source has received increasing attention. Among the many solar cell technologies, perovskite solar cells stand out for their excellent performance and huge development potential.

[0003] Perovskite solar cells have the significant advantages of high efficiency and low cost. Compared with traditional silicon-based solar cells, the preparation process of perovskite materials is relatively simple and low-cost. At the same time, its photoelectric conversion efficiency has achieved an amazing breakthrough in a short period of time, and has approached or even surpassed the efficiency level of traditional solar cells in some cases. This makes perovskite solar cells have broad application prospects in the future energy market. However, to achieve the high performance and stability of perovskite solar cells, the key lies in the crystallization quality of the perovskite precursor layer. High-quality perovskite precursor layers can effectively improve the photoelectric conversion efficiency, stability and life of the battery. At present, gradient annealing, as an important process for preparing high-quality perovskite precursor layers, is gradually becoming a research focus. By precisely controlling the temperature gradient during the annealing process, the crystallization process of the perovskite precursor layer can be optimized, the crystallization quality can be improved, and the generation of defects can be reduced, thereby significantly improving the performance of perovskite solar cells.

[0004] Under the current energy and environmental situation, the development of efficient, stable and low-cost perovskite solar cell technology has great strategic significance and economic value. Therefore, the research on the preparation process of perovskite precursor layer in perovskite solar cells, especially the innovation and optimization of gradient annealing process, has become a key task in this field. Summary of the invention

[0005] In view of this, the purpose of this application is to provide a perovskite gradient annealing process and a cell thereof, which are used to improve the photoelectric conversion efficiency of perovskite cells.

[0006] In order to achieve the above technical purpose, the present application provides a perovskite gradient annealing process, including a perovskite film substrate, and the annealing process includes the following steps:

[0007] Annealing: heating the upper and lower sides or one side of the perovskite film substrate to a preset temperature and keeping the temperature for a period of time; wherein, by setting different preset temperatures for the upper and lower sides of the perovskite film substrate, a temperature difference is generated between the upper and lower sides of the perovskite film substrate during the heat preservation stage;

[0008] Annealing is performed at least twice, and from the second annealing, the temperature difference between the upper and lower sides of the perovskite film substrate in the insulation stage is adjusted by adjusting the preset temperature to be opposite to the temperature difference in the previous annealing;

[0009] The temperature difference of the first annealing is greater than or equal to the temperature difference of the subsequent annealing.

[0010] Furthermore, the perovskite film substrate includes a conductive substrate, an electron transport layer or a hole transport layer, and a perovskite precursor layer which are arranged in sequence.

[0011] Furthermore, the perovskite film substrate is placed in an annealing device with the conductive substrate on top and the perovskite precursor layer on the bottom.

[0012] Furthermore, during the first annealing, the upper and lower sides of the perovskite film substrate are heated so that the temperature of the conductive substrate side is higher than the temperature of the perovskite precursor layer side.

[0013] Further, the heating temperature of the conductive substrate side close to the perovskite film substrate is 50-100° C., and the heating temperature of the side close to the perovskite precursor layer is 25-80° C. Further, the annealing temperature is 25-180° C., and the annealing time is 1-180 min.

[0014] Furthermore, the perovskite precursor layer is formed by coating a perovskite solution; the perovskite solution includes one or more of lead iodide, lead bromide, lead chloride, methylamine iodide, methylamine iodide, cesium iodide, DMF, DMSO, and NMP.

[0015] Furthermore, the concentration of the perovskite solution is determined by Pb 2+ When the concentration is the benchmark, the concentration is 0.5~3mol / L and the viscosity is 0.1~15mPa*s.

[0016] Secondly, the present application also provides a perovskite battery core component, which is prepared by the above-mentioned perovskite gradient annealing process.

[0017] The present application also provides a battery, including a perovskite battery core component.

[0018] In summary, the present application provides a perovskite gradient annealing process, including a perovskite film substrate, and the annealing steps are as follows: annealing at least twice, each annealing heats the upper and lower sides or one of the sides of the perovskite film substrate respectively, so that there is a temperature difference between the upper and lower sides of the perovskite film substrate; starting from the second annealing, the temperature difference direction between the upper and lower sides of the perovskite film substrate is opposite to the temperature difference direction of the previous annealing. The present application adopts an alternating gradient annealing method to make the prepared perovskite battery have a higher photoelectric conversion efficiency. Compared with the prior art, the annealing process provided by the present application can improve the crystallinity of the battery material, reduce the defect state density, optimize the charge transfer channel, and make the separation and transmission of photogenerated carriers more efficient, thereby significantly improving the ability of the perovskite battery to convert light energy into electrical energy; at the same time, the annealing process provided by the present application can also flexibly adjust the annealing temperature and annealing time, so it can be optimized for different material properties and process requirements during the production process, thereby avoiding unnecessary energy waste, achieving efficient utilization of resources, and effectively reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 A schematic diagram of the perovskite film substrate provided in Example 1 of the present application being fixedly arranged in an annealing device;

[0021] Figure 2 A schematic diagram of the reaction process inside the first annealed perovskite precursor layer provided in Example 1 of the present application;

[0022] Figure 3 A schematic diagram of the reaction process inside the second annealing perovskite precursor layer provided in Example 1 of the present application;

[0023] Figure 4 A schematic diagram of the reaction process inside the third annealing perovskite precursor layer provided in Example 1 of the present application;

[0024] Figure numerals: 101, 201, 301, 401 are all upper heating plates; 102, 202, 302, 402 are all perovskite film substrates; 103, 203, 303, 403 are all lower heating plates. DETAILED DESCRIPTION

[0025] The technical solutions of the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the specification of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection requested by the present application.

[0026] The sources of all raw materials in the present invention are not particularly limited and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0027] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0028] Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0029] The present invention provides a perovskite gradient annealing process for treating a perovskite film substrate. The annealing process comprises the following steps:

[0030] Annealing: heating the upper and lower sides or one side of the perovskite film substrate to a preset temperature and keeping it warm for a period of time;

[0031] It should be noted that during the annealing process, when both sides are heated at the same time, the preset temperatures on both sides are different; in this embodiment, at least two annealings are performed, and starting from the second annealing, the preset temperatures on both sides are adjusted so that the temperature difference direction between the upper and lower sides of the perovskite film substrate during the insulation stage is opposite to the temperature difference direction of the previous annealing; if one side is heated, the heated side is replaced during each heating process so that the heated side reaches the preset temperature, the temperature of the heated side is always higher than the unheated side, and as the heated side is replaced, the direction of the temperature difference is also replaced.

[0032] The preset temperature of heating on both sides or heating on one side will form a temperature difference on both sides of the perovskite film substrate, and since the second annealing, the temperature difference of annealing is less than or equal to the temperature difference of the first annealing.

[0033] In a specific implementation, when the upper and lower sides of the perovskite film substrate are heated simultaneously, and the annealing temperature is adjusted, the following two situations are formed:

[0034] The first one is that in the first annealing stage, when the upper preset temperature is set higher than the lower preset temperature, a temperature difference is generated between the upper and lower sides of the perovskite film substrate during the insulation stage; in the second annealing stage, the preset temperatures of the upper and lower sides of the perovskite film substrate are adjusted so that the upper preset temperature is lower than the lower preset temperature, that is, the direction of the temperature difference in the insulation stage is opposite to that in the first insulation stage; in the third annealing stage, the preset temperatures of the upper and lower sides of the perovskite film substrate are adjusted again so that the upper preset temperature is higher than the lower preset temperature, and at this time, the direction of the temperature difference in the insulation stage is opposite to that in the second insulation stage; if multiple annealing operations are required later, the direction of the temperature difference change is similar.

[0035] The second method is that in the first annealing stage, the upper preset temperature is set lower than the lower preset temperature, and a temperature difference is generated between the upper and lower sides of the perovskite film substrate during the insulation stage; in the second annealing stage, the preset temperatures of the upper and lower sides of the perovskite film substrate are adjusted so that the upper preset temperature is higher than the lower preset temperature, that is, the direction of the temperature difference in the insulation stage is opposite to that in the first insulation stage; in the third annealing stage, the preset temperatures of the upper and lower sides of the perovskite film substrate are adjusted again so that the upper preset temperature is lower than the lower preset temperature, and at this time, the direction of the temperature difference in the insulation stage is opposite to that in the second insulation stage; if multiple annealing operations are required later, the direction of the temperature difference change is similar.

[0036] When heating one side of the perovskite film substrate, in the first annealing stage, one side of the perovskite film substrate is heated to a preset temperature, so that a temperature difference is generated between the upper and lower sides of the perovskite film substrate during the insulation stage; in the second annealing stage, the other side of the perovskite film substrate is heated to a preset temperature, so that the direction of the temperature difference in the insulation stage is opposite to that of the first insulation stage; in the third annealing stage, the heated side is switched again so that the direction of the temperature difference is opposite to that of the second insulation stage; if multiple annealing operations are required subsequently, the direction of the temperature difference change is similar.

[0037] It should be noted that in the process of heating the perovskite film substrate, by changing the temperature difference direction of the upper and lower sides of the perovskite film substrate in each annealing process, the solvent in the perovskite precursor layer migrates up and down inside the perovskite precursor layer along the temperature difference direction and escapes, and finally forms a dense crystal. In the process of the first annealing, using a higher temperature for annealing is conducive to promoting large-scale nucleation, but also because the temperature of the first annealing is high, a large amount of solvent migrates and escapes in a short time, so that a large number of defect states are formed in the perovskite precursor layer. Therefore, when the subsequent annealing temperature is lower than the first annealing temperature, due to the low annealing temperature, the migration and escape rate of the remaining small amount of solvent is slow, and the defect state formed by its migration is lower than the first annealing temperature, and each time the remaining solvent migrates, it will gradually dissolve the crystallized small grains and recrystallize them during the migration process, thereby repairing the defect states formed in the previous annealing on both sides of the perovskite precursor layer, thereby strengthening the crystallinity on both sides of the perovskite precursor layer, optimizing the charge transfer channel, promoting the separation and transmission of photogenerated carriers, and significantly improving the ability of perovskite cells to convert light energy into electrical energy.

[0038] In some embodiments, the perovskite thin film substrate includes a conductive substrate, an electron transport layer or a hole transport layer, and a perovskite precursor layer disposed in sequence.

[0039] It should be noted that a functional passivation layer may be provided between each layer to improve the interface contact effect between the layers or enhance the performance of each layer, which helps to improve the stability and photoelectric conversion efficiency of the perovskite battery.

[0040] Preferably, the perovskite film substrate is placed in an annealing device with the conductive substrate on top and the perovskite precursor layer on the bottom.

[0041] More preferably, during the first annealing, the upper and lower sides of the perovskite film substrate are heated so that the temperature of the conductive substrate side is higher than the temperature of the perovskite precursor layer side.

[0042] Furthermore, the heating temperature of the conductive substrate side close to the perovskite film substrate is 50-100°C; the heating temperature of the conductive substrate side close to the perovskite precursor layer is 25-80°C.

[0043] It should be noted that the perovskite film substrate is placed upside down in the annealing device, and the conductive substrate side of the perovskite film substrate is heated. At this time, the solvent in the perovskite precursor layer migrates and diffuses from top to bottom, and the upper perovskite precursor layer quickly nucleates to form crystals; during the second annealing, the temperature difference direction is switched so that the temperature on one side of the perovskite precursor layer is higher than the temperature on the conductive substrate side of the perovskite film substrate. At this time, the solvent in the perovskite precursor layer migrates and diffuses from bottom to top, and the lower perovskite precursor layer quickly nucleates to form crystals. Since a large amount of solvent escapes from the perovskite precursor layer during the first annealing, it is easy to form large cavities inside the perovskite precursor layer, resulting in uneven crystallization; when a small amount of solvent participates in the second annealing, the defects formed inside the perovskite precursor layer are smaller, and at the same time, the solvent dissolves and re-crystallizes some of the crystallized small grains during the migration process, making up for the defects in the initial crystallization process, further improving the crystallinity of the perovskite precursor layer, and thus improving the photoelectric conversion efficiency of the battery.

[0044] In some embodiments, the annealing temperature is 25-180° C., and the annealing time is 1-180 min.

[0045] It should be noted that at a suitable temperature, the molecules or ions in the perovskite material can obtain sufficient energy to arrange themselves in an orderly manner in the lattice, forming a more complete and regular crystal structure; sufficient annealing time can ensure that the crystal growth process is fully carried out at this time. The annealing temperature and annealing time provided in this embodiment cooperate with each other, which helps to form a dense perovskite precursor layer and reduces the energy consumption required for the annealing process.

[0046] In some embodiments, the perovskite precursor layer is coated by a perovskite solution; the perovskite solution includes one or more of lead iodide, lead bromide, lead chloride, methylamine iodide, methylamine iodide, cesium iodide, DMF, DMSO, and NMP.

[0047] Preferably, the concentration of the perovskite solution is Pb 2+ When the concentration is the benchmark, the concentration is 0.5~3mol / L and the viscosity is 0.1~15mPa*s.

[0048] The applicant further provides the following reference specific embodiments to describe the present invention. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0049] Example 1

[0050] See also Figures 1 to 3 , this embodiment provides a perovskite gradient annealing process, the specific steps are as follows:

[0051] Step S1, coating a perovskite solution on a substrate by a slit coating method to obtain a perovskite film substrate, and inverting the perovskite film substrate in an annealing device with the perovskite precursor layer at the bottom to fix it; wherein the substrate is composed of a FTO conductive substrate with a nickel oxide coating attached;

[0052] Step S2, first annealing: start the upper heating plate 201 to heat, so that the heat radiation is conducted from top to bottom, at this time the lower heating plate 203 can be started or turned off, to ensure that the heat radiation of the upper heating plate 201 is higher than that of the lower heating plate 203, and keep warm for a preset time;

[0053] Step S3, second annealing: After the first annealing is completed, the lower heating plate 303 is started for heating, and the upper heating plate 301 can be started or turned off. At this time, it is ensured that the heat radiation of the lower heating plate 303 is higher than the heat radiation of the upper heating plate 301, and the heat preservation time is preset;

[0054] Step S4, the third annealing: After the second annealing is completed, the upper heating plate 401 is started for heating, and the lower heating plate 403 can be started or turned off. At this time, it is ensured that the thermal radiation of the upper heating plate 401 is higher than the thermal radiation of the lower heating plate 403. After keeping warm for a period of time, the core components of the perovskite battery are obtained.

[0055] In this embodiment, the heating temperature and heating time are shown in Table 1.

[0056] The photoelectric conversion efficiency of the perovskite battery core components prepared above was tested.

[0057] Example 2

[0058] This embodiment provides a perovskite gradient annealing process, which is different from Embodiment 1 in that the heating temperature and heating time of steps S2 to S3 are different. The specific parameters are shown in Table 1.

[0059] Example 3

[0060] This embodiment provides a perovskite gradient annealing process, which is different from Embodiment 1 in that the heating temperature and heating time of steps S2 to S3 are different. The specific parameters are shown in Table 1.

[0061] Comparative Example 1

[0062] This embodiment provides a perovskite gradient annealing process, comprising the following steps:

[0063] Step S1, coating a perovskite solution on a substrate by a slit coating method to obtain a perovskite film substrate, and inverting the perovskite film substrate in an annealing device with the perovskite precursor layer at the bottom to fix it; wherein the substrate is composed of a FTO conductive substrate with a nickel oxide coating attached;

[0064] Step S2, first annealing: start the upper heating plate to heat, so that the heat radiation is conducted from top to bottom. At this time, the lower heating plate can be started or turned off. At this time, ensure that the heat radiation of the upper heating plate is higher than that of the lower heating plate. Keep warm for a period of time to obtain a perovskite battery.

[0065] In this embodiment, the heating temperature and heating time of step S2 are shown in Table 1.

[0066] Comparative Example 2

[0067] This embodiment provides a perovskite gradient annealing process, comprising the following steps:

[0068] Step S1, coating a perovskite solution on a substrate by a slit coating method to obtain a perovskite film substrate, and placing the perovskite film substrate upright in an annealing device with the perovskite precursor layer on top, wherein the substrate is composed of a FTO conductive substrate with a nickel oxide coating attached thereto;

[0069] Step S2, first annealing: start the upper heating plate to heat, so that the heat radiation is conducted from top to bottom. At this time, the lower heating plate can be started or turned off. At this time, ensure that the heat radiation of the upper heating plate is higher than that of the lower heating plate. Keep warm for a period of time to obtain a perovskite battery.

[0070] In this embodiment, the heating temperature and heating time of step S2 are shown in Table 1.

[0071] The results of the above examples and comparative examples can be found in Table 1.

[0072] Table 1

[0073]

[0074] According to the test results in this embodiment,

[0075] Examples 1 to 3 used inversion and gradient annealing methods, and the photoelectric conversion efficiency of the core components of the perovskite battery obtained was 16.2%, 17.1%, and 16.5%, respectively. Comparative Example 1 used inversion and one-step annealing methods, and the photoelectric conversion efficiency of the core components of the perovskite battery obtained was 16.1%; Comparative Example 2 used upright and one-step annealing methods, and the photoelectric conversion efficiency of the core components of the perovskite battery obtained was 15.8%.

[0076] From the data comparison of the above-mentioned comparative example 1 and comparative example 2, it can be seen that the inverted form in the annealing process can effectively improve the photoelectric conversion efficiency of the core component of the perovskite battery. According to the data comparison of Examples 1 to 3 and Comparative Example 1, it can be seen that the gradient annealing process can further improve the photoelectric conversion efficiency of the core component of the perovskite battery. According to the data comparison of Examples 1 to 3 and Comparative Example 2, in the case of an inverted perovskite film substrate, the combination of the gradient annealing process can greatly improve the photoelectric conversion efficiency of the battery.

[0077] According to the data comparison of Example 1 and Example 2, in the process of inverted gradient annealing, the first annealing, i.e., the use of a large temperature difference annealing for the conductive substrate, can improve the photoelectric conversion efficiency of the core components of the perovskite battery; According to the data comparison of Example 2 and Example 3, in the subsequent annealing process, the high temperature may destroy the crystallized nucleus, and is also not conducive to the growth of the later crystal nucleus. Therefore, during the first annealing process, a higher temperature difference annealing is used for the conductive substrate, which is conducive to promoting large-scale nucleation on the high temperature side; in the subsequent annealing process, the annealing temperature difference can be reduced, so that the solvent dissolves the small crystal grains that have been crystallized in the film and recrystallizes. The above-mentioned annealing process is combined to form a perovskite film with few defects and dense crystal structure, thereby improving the photoelectric conversion efficiency of the battery.

[0078] The above are only preferred embodiments of the present application and are not intended to limit the present invention. Although the present application has been described in detail with reference to the examples, those skilled in the art can still modify the technical solutions recorded in the aforementioned examples or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A perovskite gradient annealing process, characterized in that: Including perovskite film substrate, annealing process The following steps are involved: Annealing: heating the upper and lower sides or one side of the perovskite film substrate to a preset temperature and keeping the temperature for a period of time; wherein, by setting different preset temperatures for the upper and lower sides of the perovskite film substrate, a temperature difference is generated between the upper and lower sides of the perovskite film substrate during the heat preservation stage; Annealing is performed at least twice, and from the second annealing, the temperature difference between the upper and lower sides of the perovskite film substrate in the insulation stage is adjusted by adjusting the preset temperature to be opposite to the temperature difference in the previous annealing; The temperature difference of the first annealing is greater than or equal to the temperature difference of the subsequent annealing.

2. The perovskite gradient annealing process according to claim 1, characterized in that: The perovskite film substrate comprises a conductive substrate, an electron transport layer or a hole transport layer, and a perovskite precursor layer which are arranged in sequence.

3. The perovskite gradient annealing process according to claim 2, characterized in that: The perovskite film substrate is placed in an annealing device with a conductive substrate on top and a perovskite precursor layer on the bottom.

4. The perovskite gradient annealing process according to claim 3, characterized in that: During the first annealing, the upper and lower sides of the perovskite film substrate are heated so that the temperature on the conductive substrate side is higher than the temperature on the perovskite precursor layer side.

5. The perovskite gradient annealing process according to claim 4, characterized in that: The heating temperature of the conductive substrate side close to the perovskite film substrate is 50-100°C; the heating temperature of the conductive substrate side close to the perovskite precursor layer is 25-80°C.

6. The perovskite gradient annealing process according to claim 1, characterized in that: The annealing temperature is 25-180° C., and the annealing time is 1-180 min.

7. The perovskite gradient annealing process according to claim 2, characterized in that: The perovskite precursor layer is formed by coating a perovskite solution; The perovskite solution includes one or more of lead iodide, lead bromide, lead chloride, methylamine iodide, methylamine iodide, cesium iodide, DMF, DMSO, and NMP.

8. The perovskite gradient annealing process according to claim 7, characterized in that: The concentration of the perovskite solution is Pb 2+ When the concentration is the benchmark, the concentration is 0.5~3mol / L and the viscosity is 0.1~15mPa*s.

9. A core component of a perovskite battery, characterized in that: Prepared by the perovskite gradient annealing process according to any one of claims 1 to 8.

10. A battery, characterized in that: Including the perovskite battery core component as described in claim 9.

Images