Perovskite / crystalline silicon laminated solar cell and preparation method thereof

Abstract

The invention discloses a perovskite / crystalline silicon laminated solar cell and a preparation method thereof, and relates to the field of solar cells, and the solar cell comprises a substrate which is provided with a light trapping layer; the light trapping layer is provided with a plurality of circular recesses, and the circular recesses are connected or disconnected and penetrate through the light trapping layer. Through the patterned structure on the light trapping layer, the light trapping efficiency is greatly enhanced, the problem of reflection loss is effectively relieved, meanwhile, the potential of the SiOx material in the aspect of passivating silicon wafer surface defects is achieved, the passivation contact efficiency is remarkably optimized, and the problem of transverse loss of the middle layer ITO is effectively avoided. In addition, deposition of a perovskite top layer cell is promoted, and high-quality formation of a perovskite thin film is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of solar energy technology, in particular to a perovskite / crystalline silicon stacked solar cell and a preparation method thereof. Background Art

[0002] Perovskite / crystalline silicon tandem solar cells have the potential advantages of high efficiency and low cost. This type of cell combines the advantages of crystalline silicon bottom cells and perovskite top cells, can rationally utilize the solar spectrum, and has become an important research direction in the photovoltaic field.

[0003] However, in traditional crystalline silicon bottom cells, defects on the silicon surface and lateral losses in the intermediate transmission layer are also key factors that restrict the improvement of battery conversion efficiency. Defects on the silicon surface can capture carriers, resulting in current loss. In addition, in order to achieve effective carrier transmission and recombination, ITO (indium tin oxide) is usually used as the intermediate electrical transmission layer. However, ITO has a high lateral conductivity, and lateral transmission losses are prone to occur in large-area batteries, further reducing the performance output of the battery. Therefore, how to effectively passivate silicon surface defects and reduce the loss of the intermediate layer has become an important research direction for improving battery performance.

[0004] In recent years, local passivation contact technology has received widespread attention in the field of crystalline silicon cells. Compared with the traditional full-coverage passivation contact design, local passivation contact effectively reduces the probability of carrier recombination on the surface by forming local contact points or contact areas on the surface of crystalline silicon, while maintaining excellent carrier transport capability. This design can significantly reduce the surface recombination current and improve the open circuit voltage and overall efficiency of the battery. However, for stacked cells, how to balance light capture efficiency, passivation performance and processing feasibility in local contact design is still an important challenge. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is how to improve the light capture capability while improving the passivation performance and the film forming property of the perovskite film.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: a perovskite / crystalline silicon stacked solar cell, comprising a substrate on which a light trapping layer is arranged; the light trapping layer has a plurality of circular depressions, which are connected or unconnected and penetrate the light trapping layer.

[0008] As a preferred solution of the perovskite / crystalline silicon tandem solar cell of the present invention, the light trapping layer is SiO x Thin film with a thickness of 50~200nm.

[0009] As a preferred solution of the perovskite / crystalline silicon tandem solar cell of the present invention, the circular depressions are arranged periodically on the light trapping layer, and the arrangement period is 300nm~2000nm.

[0010] As a preferred solution of the perovskite / crystalline silicon tandem solar cell of the present invention, the diameter of the circular depressions ranges from 0.3 to 2 μm, and the intervals between the circular depressions are equal.

[0011] As a preferred solution of the perovskite / crystalline silicon stacked solar cell of the present invention, the substrate comprises an n-type crystalline silicon layer, an ultra-thin tunneling silicon oxide layer and an n-type polycrystalline silicon layer stacked in sequence from bottom to top.

[0012] As a preferred solution of the perovskite / crystalline silicon tandem solar cell of the present invention, the thickness of the n-type crystalline silicon layer is 130-160 μm, the thickness of the ultra-thin tunneling silicon oxide layer is 1-2 nm, and the thickness of the n-type polycrystalline silicon layer is 100 nm.

[0013] On the other hand, the present invention also provides a method for preparing a perovskite / crystalline silicon stacked solar cell, which is used to prepare the above-mentioned perovskite / crystalline silicon stacked solar cell, and the preparation method comprises forming a layer of small ball array on a substrate; adjusting the diameter of the small ball to a specified size; forming a layer of SiO on the surface of the substrate and the small ball array x Thin film; removing SiO from the surface of the ball and the ball array x film to form a light trapping layer.

[0014] As a preferred embodiment of the method for preparing the perovskite / crystalline silicon tandem solar cell of the present invention, wherein: removing the SiO x After the film is formed, the light trapping layer has circular depressions corresponding to the small balls one by one.

[0015] As a preferred solution of the method for preparing the perovskite / crystalline silicon tandem solar cell of the present invention, the array of small balls is formed by spin coating or solution injection, and the diameter of the small balls is 0.3-2 μm.

[0016] As a preferred solution of the method for preparing the perovskite / crystalline silicon stacked solar cell of the present invention, the substrate comprises an n-type crystalline silicon layer, an ultra-thin tunneling silicon oxide layer and an n-type polycrystalline silicon layer stacked in sequence from bottom to top.

[0017] The beneficial effects of the present invention are as follows: the present invention greatly improves the light capture efficiency through the patterned structure on the light trapping layer, effectively alleviates the problem of reflection loss, and realizes SiO xThe material's potential in passivating silicon wafer surface defects significantly optimizes the passivation contact performance and effectively avoids the lateral loss problem of the middle layer ITO. In addition, it also promotes the smooth deposition of the perovskite top cell and ensures the high-quality formation of high-quality perovskite films. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 Schematic diagram of the substrate and light trapping layer structure of the perovskite / crystalline silicon stacked solar cell.

[0020] Figure 2 Schematic diagram of the front view when preparing small balls for perovskite / crystalline silicon tandem solar cells.

[0021] Figure 3 Schematic diagram of the front view of step 3 in the preparation of perovskite / crystalline silicon tandem solar cells.

[0022] Figure 4 This is a cross-sectional view of step 3 of preparing a perovskite / crystalline silicon tandem solar cell.

[0023] Figure 5 A cross-sectional view of step 4 of a perovskite / crystalline silicon tandem solar cell.

[0024] Figure 6 Scanning electron microscope (SEM) surface image of PS balls processed by 0W power reactive ion etching and the corresponding light trapping layer structure.

[0025] Figure 7 Scanning electron microscope (SEM) surface image of PS beads treated with 80W reactive ion etching for 10 minutes and the corresponding light trapping layer structure.

[0026] Figure 8 Scanning electron microscope (SEM) surface image of PS beads treated with 80W reactive ion etching for 15 minutes and the corresponding light trapping layer structure.

[0027] Fig. 9 This is the relationship between the reflectivity and wavelength of the samples without light trapping layer structure, 0W, 80W treatment for 10 minutes and 80W treatment for 15 minutes in the experiment.

[0028] Fig.10The relationship between the average reflectivity and duty cycle of the samples obtained for the experiment and simulation of the patterned structure without light trapping layer, 0W, 80W treatment for 10 minutes and 80W treatment for 15 minutes.

[0029] Fig.11 The simulated relationship between the photocurrent density and duty cycle of perovskite, crystalline silicon and the sum of the two.

[0030] Fig.12 The simulated relationship between the total photocurrent density of perovskite and crystalline silicon samples with three representative duty cycle and the refractive index n of the light trapping layer.

[0031] Fig.13 This is the surface potential distribution diagram of the light trapping layer patterned structure film.

[0032] Fig.14 This is the current distribution diagram of the thin film with patterned structure of light trapping layer.

[0033] Fig.15 Dark IV curves of samples treated with 0 W, 80 W for 10 minutes, and 80 W for 15 minutes.

[0034] Fig.16 Top view and cross-sectional SEM images of perovskite deposited on silicon substrate without light trapping layer patterning film.

[0035] Fig.17 Top view and cross-sectional SEM images of perovskite deposited on silicon substrate in the case of a light trapping layer patterned film processed by reactive ion etching at 0 W power.

[0036] Fig.18 Top view and cross-sectional SEM images of the perovskite deposited on a silicon substrate in the case of a light trapping layer patterned film treated with 80 W reactive ion etching for 10 min.

[0037] Fig.19 Top view and cross-sectional SEM images of the perovskite deposited on a silicon substrate in the case of a light trapping layer patterned film processed by reactive ion etching at 80 W power for 15 min.

[0038] Fig. 20 PL intensity mapping of perovskite films grown on samples without light trapping layer patterning, 0 W, 80 W treatment for 10 min, and 80 W treatment for 15 min.

[0039] Fig.21 PL spectra of samples obtained for the light-trapping layer patterned structure, 0 W, 80 W treatment for 10 min, and 80 W treatment for 15 min at the initial and after light immersion.

[0040] In the figure: 100, substrate; 200, light trapping layer; 201, circular depression; 300, n-type crystalline silicon layer; 400, ultra-thin tunneling silicon oxide layer; 500, n-type polycrystalline silicon layer. DETAILED DESCRIPTION

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0043] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is mutually exclusive with other embodiments, either individually or selectively.

[0044] Example 1, reference Figure 1 , which is the first embodiment of the present invention, provides a perovskite / crystalline silicon tandem solar cell. The perovskite / crystalline silicon tandem solar cell includes a substrate 100 and a light trapping layer 200.

[0045] Specifically, refer to Figure 1 The light trapping layer 200 covers the upper surface of the substrate 100, and has a plurality of circular depressions 201 on the light trapping layer 200. The circular depressions 201 may be connected or not connected. The light trapping layer 200 is SiO x film.

[0046] Preferably, the circular depressions 201 are periodically arranged on the light trapping layer 200, and the arrangement period is 1 μm.

[0047] Preferably, the diameter of the circular depressions 201 is 0.5-1 μm and the intervals between the circular depressions 201 are equal.

[0048] Preferably, refer to Figure 1 The substrate 100 includes an n-type crystalline silicon layer 300 , an ultra-thin tunneling silicon oxide layer 400 , and an n-type polysilicon layer 500 . The ultra-thin tunneling silicon oxide layer 400 covers the n-type crystalline silicon layer 300 , and the n-type polysilicon layer 500 covers the ultra-thin tunneling silicon oxide layer 400 .

[0049] The light trapping layer 200 and the n-type polysilicon layer 500 form a local contact structure for improving the passivation contact performance.

[0050] The light trapping layer 200 is used to stack an intermediate layer of the perovskite / crystalline silicon stacked solar cell. The intermediate layer can fully penetrate into the circular depression 201 and fully contact with the n-type polysilicon layer 500.

[0051] Covering the light trapping layer 200 on the surface of the substrate 100 can passivate silicon surface defects and improve the passivation contact performance through local contact with the n-type polysilicon layer 500. Depositing an intermediate layer on the light trapping layer 200 can effectively reduce the lateral transmission loss of the intermediate layer.

[0052] The present invention is used on the surface of crystalline silicon bottom cells to generate high-quality perovskite films by promoting uniform deposition of perovskite top cells. At the same time, the perovskite / crystalline silicon stacked solar cell greatly improves the light capture efficiency and reduces reflection losses through the design of the light trapping layer 200 structure, and further optimizes the passivation contact efficiency, while effectively avoiding the lateral transmission loss problem of the middle layer ITO, thereby improving the overall photoelectric conversion efficiency.

[0053] Example 2, reference Figure 2~Figure 5 , which is the second embodiment of the present invention, and this embodiment is based on the previous embodiment. The present invention provides a method for preparing a perovskite / crystalline silicon tandem solar cell, which can prepare the perovskite / crystalline silicon tandem solar cell described in embodiment 1. The preparation method comprises: S1: forming a layer of ball array on the substrate 100.

[0054] Specifically, refer to Figure 2 A layer of tightly packed polystyrene (PS) ball array is prepared on the substrate 100 by solution injection method. In the solution injection method, a single layer can be spread by spreading the ball onto the water surface through a needle tube through an automatic device, and the needle tip is in contact with the water surface. The result prepared in this way is periodic. The result prepared by direct spin coating of the solution is non-uniform.

[0055] S2: The polystyrene (PS) beads are processed by reactive ion etching, and the size of the polystyrene (PS) beads is changed by adjusting the etching power and time to obtain the desired bead size.

[0056] S3: Reference Figure 3 and Figure 4 , a layer of SiO was coated on the PS ball array by electron beam evaporation. x film.

[0057] S4: Reference Figure 5 The PS beads and the SiO2 coating on the PS beads were removed by a stripping process. xThe thin film only retains the SiO2 with regularly arranged circular holes attached to the substrate. x The patterned structure finally forms a light trapping layer 200 having circular depressions 201 .

[0058] Example 3, reference Figure 6~Figure 12 , which is the third embodiment of the present invention, and is based on the first two embodiments. This embodiment verifies the beneficial effects of the present invention through experiments.

[0059] Specifically, in this embodiment, the light trapping layer 200 processed by 0W power reactive ion etching is used as the local contact structure, and its SEM surface image is as follows: Figure 6 shown.

[0060] The SEM surface image of the light trapping layer 200 structure treated by 80W power reactive ion etching for 10 minutes is as follows: Figure 7 shown.

[0061] The SEM surface image of the light trapping layer 200 structure treated by 80W power reactive ion etching for 15 minutes is as follows: Figure 8 shown.

[0062] The test results show that the reflectivity of the sample of this embodiment is significantly lower than the reflectivity of the sample without the circular depression 201 structure, which indicates that the design of this embodiment can reduce the reflection loss. Fig. 9 shown.

[0063] The simulated relationship between the average reflectivity and the duty cycle also verifies that the design of the light trapping layer 200 structure of the present invention can reduce the reflectivity of the device, and the relationship between the average reflectivity and the duty cycle is in good agreement with the experimental results.

[0064] from Fig.10 It can be seen that the duty cycle of the light trapping layer 200 structure processed by 0W power reactive ion etching is approximately 0.9; the duty cycle of the light trapping layer 200 structure processed by 80W power reactive ion etching for 10 minutes is about 0.75; the duty cycle of the light trapping layer 200 structure processed by 80W power reactive ion etching for 15 minutes is about 0.45. The average reflectivity is proportional to the duty cycle.

[0065] The effect of changing the duty cycle on the optical response of the two subcells in the tandem cell, namely the perovskite top cell and the silicon bottom cell, is shown in Figure 2. Fig.11 As shown in the figure, the photocurrent density of the perovskite top cell decreases with the increase of duty cycle, while the photocurrent density of the silicon bottom cell increases first and then enters a plateau period. The total photocurrent density of the two increases first and then decreases, reaching the maximum value when the duty cycle is 0.9.

[0066] When the duty cycle is 1, that is, when the light trapping layer 200 structure is not introduced, the photocurrent density is reduced. This shows that the design of this embodiment can maximize the absorption of sunlight by the perovskite / crystalline silicon tandem solar cell, reduce losses, and improve light absorption efficiency, and can significantly improve the light management capability of the perovskite / crystalline silicon tandem solar cell.

[0067] The relationship between the total photocurrent density of the perovskite top cell and the silicon bottom cell and the refractive index n value of the light trapping layer 200 is as follows: Fig.12 As shown. When the refractive index n of the light trapping layer 200 structure film is in the range of 1.5-2.2, the greater the duty cycle, the greater the total photocurrent density of the two cells. When the refractive index n of the light trapping layer 200 structure film is in the range of 2.2-3, the smaller the duty cycle, the greater the total photocurrent density of the two cells. This shows that the refractive index of the material used in the light management structure with light trapping ability has an impact on the optical response of the device with the structure.

[0068] Example 4: This example also verifies the beneficial effects of the present invention through experiments.

[0069] Specifically, the potential distribution of the light trapping layer 200 is as follows: Fig.13 As shown, the potential of the area with the circular depression 201 is higher than that of the substrate 100 filled inside the circular depression 201. And the current of the exposed area of ​​the substrate 100 is higher than that of the SiO2 with the circular depression 201. x Area, such as Fig.14 As shown, it can be concluded that SiO x The conductivity of the region is inferior to that of the substrate 100 in the inner region of the circular recess 201. This undoubtedly improves the passivation contact characteristics and improves the performance of the device.

[0070] And from the dark IV curves of the light trapping layer 200 structure device samples with 0W, 80W treatment for 10 minutes and 80W treatment for 15 minutes, a standard linear curve can be observed, representing a typical ohmic behavior. The larger the slope (i.e. the maximum value for 0W treatment), the smaller the specific contact resistivity, and the lower the contact resistivity, the better the contact characteristics, such as Fig.15 The contact capabilities of the light trapping layer 200 structure films obtained by different processing methods are different.

[0071] Example 5: This example also verifies the beneficial effects of the present invention through experiments.

[0072] Specifically, the top view and cross-sectional SEM images of the perovskite deposited on the substrate 100 without the light trapping layer 200 structure film are shown in FIG. Fig.16 shown.

[0073] The top view and cross-sectional SEM images of the perovskite deposited on the substrate 100 in the case of the light trapping layer 200 structure film processed by reactive ion etching with 0W power, as shown in FIG. Fig.17 shown.

[0074] The top view and cross-sectional SEM images of the perovskite deposited on the substrate 100 in the case of the light trapping layer 200 structure treated by 80W power reactive ion etching for 10 minutes are shown as follows: Fig.18 shown.

[0075] The top view and cross-sectional SEM images of the perovskite deposited on the substrate 100 in the case of the light trapping layer 200 structure treated by 80W power reactive ion etching for 15 minutes are shown as follows: Fig.19 shown.

[0076] By comparison, it can be found that the grain sizes of the perovskite films deposited on the structures with different treatment methods and without the light trapping layer 200 are different. The perovskite grains deposited on the light trapping layer 200 structure treated with 0W power are the largest compared with those treated with other methods, indicating better film forming properties.

[0077] The steady-state photoluminescence (PL) measurements were performed on the perovskite surface grown on the light trapping layer 200 structure without the light trapping layer 200 structure and the light trapping layer 200 structure with three treatments. The PL intensity mapping is shown in Fig. 20 As shown, the perovskite deposited on the light trapping layer 200 structure after 0W power reactive ion etching treatment and 80W power reactive ion etching treatment for 10 minutes has stronger PL emission, indicating that the perovskite film is better.

[0078] The PL emission curve under long-term illumination conditions is as follows Fig.21 As shown. The PL intensity of the perovskite deposited on the light trapping layer 200 structure treated by 0W power reactive ion etching is higher than that of other cases. It can be clearly seen that the PL curve on the surface of the perovskite deposited on the light trapping layer 200 structure treated by 0W power reactive ion etching after light immersion can be well maintained, while the samples in other cases have obvious collapse and displacement, indicating that the perovskite may have unstable phenomena such as phase separation.

[0079] This means that the introduction of this example design can improve the quality, stability and film formation of perovskite films.

[0080] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A perovskite / crystalline silicon tandem solar cell, characterized in that: include, A substrate (100) having a light trapping layer (200) disposed thereon; The light trapping layer (200) has a plurality of circular depressions (201), wherein the circular depressions (201) are connected or unconnected to each other and penetrate the light trapping layer (200); An intermediate layer of the perovskite / crystalline silicon stacked solar cell is stacked above the light trapping layer (200), and the intermediate layer can penetrate into the circular recess (201).

2. The perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that: The light trapping layer (200) is SiO x Thin film with a thickness of 50~200nm.

3. The perovskite / crystalline silicon tandem solar cell according to claim 2, characterized in that: The circular depressions (201) are periodically arranged on the light trapping layer (200), and the arrangement period is 300nm to 2000nm.

4. The perovskite / crystalline silicon tandem solar cell according to claim 3, characterized in that: The diameter of the circular depressions (201) ranges from 0.3 to 2 μm, and the intervals between the circular depressions (201) are equal.

5. The perovskite / crystalline silicon tandem solar cell according to claim 4, characterized in that: The substrate (100) comprises an n-type crystalline silicon layer (300), an ultra-thin tunneling silicon oxide layer (400) and an n-type polycrystalline silicon layer (500) which are stacked in sequence from bottom to top.

6. The perovskite / crystalline silicon tandem solar cell according to claim 5, characterized in that: The thickness of the n-type crystalline silicon layer (300) is 130-160 μm, the thickness of the ultra-thin tunneling silicon oxide layer (400) is 1-2 nm, and the thickness of the n-type polycrystalline silicon layer (500) is 100 nm.

7. A method for preparing a perovskite / crystalline silicon tandem solar cell, characterized in that: Forming a layer of small ball array on a substrate (100); Adjusting the diameter of the ball to a specified size; A layer of SiO is formed on the surface of the substrate (100) and the ball array. x film; Removing SiO from the surface of the ball and the ball array x The film is formed into a light trapping layer (200).

8. The method for preparing a perovskite / crystalline silicon tandem solar cell according to claim 7, characterized in that: Removing SiO from the surface of the ball and the ball array x After the film is formed, the light trapping layer (200) has circular depressions (201) corresponding one to one to the small balls.

9. The method for preparing a perovskite / crystalline silicon tandem solar cell according to claim 8, characterized in that: The small ball array is formed by spin coating or solution injection, and the diameter of the small ball is 0.3-2 μm.

10. The method for preparing a perovskite / crystalline silicon tandem solar cell according to claim 9, characterized in that: The substrate (100) comprises an n-type crystalline silicon layer (300), an ultra-thin tunneling silicon oxide layer (400) and an n-type polycrystalline silicon layer (500) which are stacked in sequence from bottom to top.

Images