Three-junction flexible solar cell

Abstract

The invention discloses a three-junction flexible solar cell, which comprises an epitaxial layer of an inverted three-junction solar cell grown on a GaAs substrate, and the epitaxial layer sequentially comprises a GaInP top cell, a GaAs middle cell and an InGaAs bottom cell from the substrate; then, an AZO film is evaporated on the surface of the InGaAs bottom cell, a plurality of pairs of Ta2O5 layers and SiO2 layers are alternately deposited on the AZO film, and a high-reflection film is formed; permanently bonding the flexible substrate and the surface, with the high-reflection film, of the epitaxial layer together to obtain a bonding sheet; and finally, the GaAs substrate is removed, the front electrode and the antireflection film are prepared, a part of AZO film is etched and exposed to serve as a back electrode, and preparation of the solar cell is completed. According to the invention, the back reflection film structure composed of the AZO film and the high reflection film is designed, so that the problem that an InGaAs bottom cell is poor in near infrared spectrum absorption is solved.

Description

[0001] This case is a divisional application of a Chinese patent, with the parent application number being 202511975259.2 and the application date being 2025-12-25. Technical Field

[0002] This invention belongs to the field of semiconductor device technology, and specifically relates to a triple-junction flexible solar cell. Background Technology

[0003] Flexible multi-junction solar cells, especially flip-chip GaInP / GaAs / InGaAs triple-junction cells, are high-efficiency photovoltaic devices for space and specialized applications. Each sub-cell absorbs different wavelengths of the solar spectrum: the GaInP top cell absorbs photons in the 300nm-670nm band, the GaAs middle cell absorbs photons in the 670nm-873nm band, and the InGaAs bottom cell absorbs photons in the 873nm-1400nm band. Based on the AM1.5G spectrum, the percentages of solar energy absorbed by each sub-cell are approximately 45%, 21%, and 17%, respectively, leaving 17% of the solar energy in the wavelength range greater than 1400nm unutilized. While the GaInP top cell absorbs the most energy, its high voltage limits its current. Therefore, the InGaAs bottom cell is crucial for increasing the total current. However, InGaAs material has a low absorption coefficient for long-wavelength photons (900nm-1400nm) and strong penetrating power; photons passing through the absorption layer in a single pass cannot be completely absorbed, making the photoelectric conversion efficiency in this band a bottleneck for improving the overall performance of the cell.

[0004] Existing technical solutions mainly focus on optimizing the front-side anti-reflective coating (ARC). For example, patent 201711441256.6 uses TiO2. x While ZnO / SiO2 antireflective coatings meet the required refractive index and have sufficient adhesion, their optimized wavelength range is mainly concentrated in the 400nm-900nm range. Their antireflective effect in the 900nm-1400nm range is limited, failing to effectively address the fundamental problem of insufficient near-infrared light absorption in InGaAs substrates. Although the ZnO / SiO2 antireflective coating structure in patent CN202110681570.1 optimizes the 300nm-1400nm range, its low reflectivity and limited antireflective effect also fail to effectively solve the fundamental problem of insufficient near-infrared light absorption in InGaAs substrates. Furthermore, the magnetron sputtering deposition of ZnO / SiO2 requires high-temperature annealing at approximately 600℃, which can cause thermal damage to the GaAs-based epitaxial layer (such as component diffusion and arsenic volatilization) and lead to glass transition and embrittlement of flexible substrates such as polyimide (PI), causing the device to lose flexibility and become damaged. Therefore, the current field of flexible solar cells lacks a battery structure design scheme that can both efficiently recycle near-infrared spectra and be compatible with low-temperature flexible fabrication processes. Summary of the Invention

[0005] The purpose of this invention is to provide a triple-junction flexible solar cell that solves the problem of poor absorption of the near-infrared spectrum by InGaAs bottom cells.

[0006] To achieve the above objectives, the present invention provides a method for fabricating a triple-junction flexible solar cell, which includes, in sequence from the back surface to the light-receiving surface of the solar cell, a flexible substrate, a high-reflection film, an AZO film, an epitaxial layer of a flip-chip triple-junction solar cell, a positive electrode, and an anti-reflection film. The epitaxial layer comprises, from the substrate, a GaInP top cell, a GaAs middle cell, and an InGaAs bottom cell in sequence. The AZO film and the high-reflectivity film form a back reflective film structure, and the portion of the AZO film exposed by etching serves as the back electrode. The high-reflectivity film is composed of multiple pairs of alternating stacked Ta2O5 layers and SiO2 layers. The refractive index of the Ta2O5 layer is 2.1 and the thickness is 140nm-150nm. The refractive index of the SiO2 layer is 1.46 and the thickness is 200nm-210nm. The number of alternating stacking periods of the Ta2O5 layer and SiO2 layer is 6-8 pairs. A Cr / Ti layer and a SiO2 bonding layer are sequentially stacked between the flexible substrate and the high-reflectivity film. The SiO2 bonding layer and the Cr / Ti layer form stress complementarity. The outermost layer of the high-reflectivity film near the flexible substrate is a SiO2 layer. The flexible substrate is bonded to the SiO2 layer in the high-reflectivity film through the SiO2 bonding layer.

[0007] Furthermore, the flexible substrate is a PI film, the AZO film is formed by electron beam evaporation at a temperature of 150℃-180℃, the high reflectivity film is formed by electron beam evaporation at a temperature of 150℃-180℃, and the bonding temperature between the SiO2 bonding layer and the SiO2 layer in the high reflectivity film is 150℃-180℃.

[0008] Furthermore, the evaporation temperature of the AZO film is 150°C, and the deposition temperature of the high-reflectivity film is 150°C.

[0009] Furthermore, in the high-reflectivity film, the thickness of the Ta2O5 layer is 143 nm, the thickness of the SiO2 layer is 205 nm, and the number of alternating stacking periods of the Ta2O5 layer and the SiO2 layer is 6 pairs.

[0010] Furthermore, the thickness of the PI film is 50 μm.

[0011] Furthermore, the thickness of the AZO film is 80nm-120nm.

[0012] Furthermore, the thickness of the AZO film is 100 nm.

[0013] Furthermore, the AZO film is aluminum-doped zinc oxide.

[0014] Furthermore, in the Cr / Ti layer, the thickness of Cr is 30nm-60nm, the thickness of Ti is 50nm-100nm, and the thickness of the SiO2 bonding layer is 500nm-1000nm.

[0015] Furthermore, the thickness of the SiO2 bonding layer is 500nm-1000nm.

[0016] After adopting the above solution, the beneficial effects of the present invention are as follows: 1. This application introduces a back reflective film structure composed of an AZO film and a high-reflectivity film on the back of the solar cell. The AZO film exhibits high near-infrared transmittance, a broad spectral response up to 1800 nm, and good bending stability, providing highly reliable back reflection. In the high-reflectivity film, the Ta2O5 layer (refractive index n=2.1) and the SiO2 layer (refractive index n=1.46) have high refractive index contrast in the near-infrared region. Multiple pairs of Ta2O5 / SiO2 layers (with the Ta2O5 layer designed to be 140nm-150nm thick and the SiO2 layer 200nm-210nm thick) can achieve a peak reflectivity >99% and a high-reflectivity bandwidth of approximately 350nm-400nm when designing the center wavelength of the InGaAs bottom cell (e.g., 1100-1200nm). Covering the 1000nm-1400nm wavelength range, it perfectly matches the absorption spectrum of the InGaAs bottom cell, and can efficiently reflect unabsorbed near-infrared photons back to the absorption layer of the InGaAs bottom cell, enabling the InGaAs bottom cell to absorb the near-infrared spectrum again, thus promoting the improvement of the short-circuit current of the entire device. Moreover, the Ta2O5 layer and SiO2 layer are both low-absorption materials in the 300nm-2000nm range, which do not introduce parasitic losses, ensuring that unabsorbed photons are efficiently returned to the InGaAs bottom cell for secondary utilization.

[0017] 2. In the design of the high-reflectivity film, the Ta2O5 layer exhibits compressive stress, while the SiO2 layer exhibits tensile stress. The alternating deposition of these two layers partially cancels out the stress, making it suitable for flexible device fabrication. Furthermore, the SiO2 bonding layer can complement the stress of the Cr / Ti layer, effectively reducing the warpage and internal stress of the entire film stack. This design ensures that the film layer is less prone to cracking or detachment during repeated bending of the battery with the integrated back reflective film, significantly improving the long-term reliability of flexible devices under complex deformation.

[0018] 3. This application uses SiO2 as the bonding medium to bond with the SiO2 layer in the high-reflectivity film, forming a SiO2-SiO2 bonding structure. SiO2 is extremely stable under humid heat, ultraviolet light, and atomic oxygen conditions, which can prevent water vapor and ions from diffusing to the sensitive epitaxial layer. Furthermore, the use of the SiO2-SiO2 bonding structure replaces the traditional precious metal (such as Au-Au) hot-press bonding structure commonly used in flexible solar cells, which not only eliminates the need for expensive gold materials and simplifies the process but also avoids the risk of metal ion contamination. Meanwhile, AZO, Ta2O5, and SiO2 are all common and environmentally friendly thin-film materials, enabling this back-reflective film structure to possess both high performance and the advantages of low cost and green production, making it very suitable for large-scale industrial applications.

[0019] 4. The growth and bonding temperatures of the AZO film, Ta2O5 layer, and SiO2 layer are all 150℃-180℃. This low-temperature system completely avoids the risk of thermal damage to GaAs-based epitaxial materials caused by high temperatures. More importantly, it ensures that flexible substrates such as PI film do not undergo glass transition, thus maintaining their flexibility and mechanical strength. This provides a key process foundation for achieving high-performance and high-reliability flexible solar cells. Attached Figure Description

[0020] Figure 1 This is a structural diagram of the epitaxial layer of the flip-chip triple-junction solar cell after growth according to the present invention.

[0021] Figure 2 This is a structural diagram of the AZO film after vapor deposition according to the present invention.

[0022] Figure 3 This is a structural diagram of the high-reflectivity film deposited according to the present invention.

[0023] Figure 4 This is a structural diagram of the present invention after Cr / Ti layer is deposited on a flexible substrate.

[0024] Figure 5 This is a structural diagram of the SiO2 bonding layer after deposition in this invention.

[0025] Figure 6 This is a structural diagram of the present invention after permanent bonding.

[0026] Figure 7 This is a structural diagram of the flexible solar cell of the present invention.

[0027] Figure 8 This is a flowchart of the preparation method of the present invention.

[0028] Label Explanation: 1. GaAs substrate; 2. Epitaxial layer; 3. AZO film; 4. High-reflection film; 5. Flexible substrate; 6. Cr / Ti layer; 7. SiO2 bonding layer; 8. Positive electrode; 9. Back electrode; 10. Anti-reflection film. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application, and the range values ​​mentioned in this application all include endpoint values.

[0030] like Figure 8 As shown, this application provides a method for fabricating a triple-junction flexible solar cell, comprising the following steps: S1. Growth of a flip-chip epitaxial layer: A GaAs substrate 1 is provided. Using an MOCVD device, a flip-chip triple-junction solar cell epitaxial layer 2 is grown on the GaAs substrate 1. The epitaxial layer 2 sequentially includes a GaInP top cell, a GaAs middle cell, and an InGaAs bottom cell from the substrate. The structure of the grown epitaxial layer is as follows: Figure 1 As shown.

[0031] S2. Deposition of AZO film: The epitaxial wafer prepared in step S1 is organically cleaned, and then an AZO film 3 is deposited on the surface of the InGaAs base cell by electron beam evaporation. The deposition temperature is 150℃-180℃, preferably 150℃, and the thickness of the AZO film 3 is 80nm-120nm, preferably 100nm. The structure after AZO film 3 deposition is as follows. Figure 2 As shown.

[0032] Optionally, organic cleaning of the epitaxial wafer includes immersing the epitaxial wafer in acetone for 10 minutes each in 3 passes and isopropanol for 1 pass, followed by rinsing with deionized water and evaporating. S3. Deposition of a high-reflectivity film: Multiple pairs of Ta2O5 and SiO2 layers are alternately stacked and deposited on the surface of AZO film 3 by electron beam evaporation to form a high-reflectivity film 4. The deposition temperature is 150℃-180℃, preferably 150℃. The Ta2O5 layer has a refractive index of 2.1 and a thickness of 140nm-150nm, preferably 143nm; the SiO2 layer has a refractive index of 1.46 and a thickness of 200nm-210nm, preferably 205nm; the number of alternating stacked Ta2O5 and SiO2 layers is 6-8 pairs, preferably 6 pairs. The structure after deposition of the high-reflectivity film 4 is as follows: Figure 3 As shown.

[0033] S4. Depositing a Cr / Ti layer on a flexible substrate: A flexible substrate 5 is provided, preferably a PI film with a thickness of 50 μm; the flexible substrate 5 is organically cleaned, and then a Cr / Ti layer 6 is deposited on the flexible substrate 5 by electron beam evaporation at room temperature. The Cr / Ti layer 6 is a composite metal layer of Cr and Ti, wherein the thickness of Cr is 30 nm-60 nm and the thickness of Ti is 50 nm-100 nm. The structure after depositing the Cr / Ti layer 6 is as follows. Figure 4 As shown.

[0034] Optionally, the organic cleaning process for the flexible substrate 5 includes immersing the flexible substrate 5 in acetone for 10 minutes in each of the three immersions and isopropanol immersions, and then baking it in an oven at 100°C for 2 hours to dry it.

[0035] S5. Deposition of SiO2 bonding layer: A SiO2 bonding layer 7 is deposited on the Cr / Ti layer 6 using a PECVD device. The thickness of the SiO2 bonding layer 7 is 500nm-1000nm. The structure after deposition of the SiO2 bonding layer 7 is as follows. Figure 5 As shown.

[0036] S6. Permanent Bonding: Align and bond the side of the flexible substrate 5 with the SiO2 bonding layer 7 to the surface of the outermost SiO2 layer of the high-reflectivity film 4, and then place it in a wafer bonding machine for permanent bonding to obtain a composite bonded wafer. The structure after permanent bonding is as follows. Figure 6 As shown.

[0037] Specifically, permanent bonding is performed by applying temperature and pressure in a vacuum environment. The bonding temperature is 150℃-180℃, the pressure is 1MPa-5MPa, and the time is 0.5h-1h. The vacuum level inside the wafer bonding machine cavity reaches the Pa level.

[0038] S7. Subsequent Processes: After bonding, the bonded wafer is removed after cooling and voltage reduction. Then, the bonded wafer undergoes a series of processes including wet etching to remove the GaAs substrate (1), photolithography and deposition of the positive electrode (8) on the front side, deposition of an anti-reflection film (10), etching to expose the AZO film as the back electrode (9), and annealing and dicing (these are standard processes and will not be detailed here). This completes the fabrication of the solar cell, resulting in a flexible solar cell structure as shown. Figure 7 As shown.

[0039] Therefore, to solve the problem of poor near-infrared spectrum absorption by InGaAs bottom cells, this application introduces a back reflection film structure on the back of the solar cell, such as... Figure 7As shown, the back reflective film consists of an AZO film 3 and a high reflective film 4, and is disposed on the back side of the epitaxial layer 2 of the solar cell. The AZO (Aluminum-Doped Zinc Oxide) film is aluminum-doped zinc oxide, essentially an N-type transparent conductive oxide. AZO has high near-infrared transmittance, a broad spectral response up to 1800 nm, good bending stability, low-temperature processing compatible with PI films, high-reliability back reflection, no metal contamination, low mass production cost, and no rare metals, making it environmentally friendly and sustainable. The thickness of the AZO film 3 is 80 nm-120 nm, preferably 100 nm.

[0040] The high-reflectivity film 4 is composed of multiple pairs of alternating stacked Ta2O5 and SiO2 layers, forming a distributed Bragg reflector structure and employing the quarter-wavelength optical thickness principle. The refractive index of the Ta2O5 layer is 2.1, and the refractive index of the SiO2 layer is 1.46. The significant difference in refractive indices between the Ta2O5 and SiO2 layers results in a wider reflection bandwidth. Furthermore, the more pairs of Ta2O5 and SiO2 layers there are, the higher the reflectivity, exhibiting high refractive index contrast in the near-infrared region. When designing the InGaAs substrate at its center wavelength (e.g., 1100-1200 nm), multiple pairs of Ta2O5 and SiO2 layers can achieve a peak reflectivity >99%, with a high-reflectivity bandwidth of approximately 350nm-400nm, covering the 1000nm-1400nm band. This perfectly matches the absorption spectrum of the InGaAs substrate, efficiently reflecting unabsorbed near-infrared photons back to the absorption layer of the InGaAs substrate.

[0041] Specifically, in order to efficiently reflect unabsorbed near-infrared photons back to the InGaAs bottom cell, the thickness of the Ta2O5 layer is designed to be 140nm-150nm, and the thickness of the SiO2 layer is designed to be 200nm-210nm. The number of alternating stacking cycles of the Ta2O5 layer and the SiO2 layer is 6-8 pairs. If the number of cycles is set too few, the optimal effect of high reflectivity will not be achieved. If it is set too many, the limit of high reflectivity will be reached, and the gain will be limited. Moreover, if the film is too thick, it will be easy to fall off when the flexible cell is bent.

[0042] Taking a Ta₂O₅ layer with a refractive index of 2.1 and a SiO₂ layer with a refractive index of 1.46 as an example, to achieve a maximum reflectivity of >99% near the center wavelength, the number of alternating stacked Ta₂O₅ and SiO₂ layers should be 6 pairs. If the center wavelength of the InGaAs bottom cell is around 1200nm, the thickness of the Ta₂O₅ layer should be 143nm and the thickness of the SiO₂ layer should be 205nm. Therefore, the preferred number of alternating stacked Ta₂O₅ and SiO₂ layers is 6 pairs, the preferred thickness of the Ta₂O₅ layer is 143nm, and the preferred thickness of the SiO₂ layer is 205nm.

[0043] Therefore, this application adopts a back reflective film structure that combines AZO film 3 and multiple pairs of stacked Ta2O5 / SiO2 high reflective films 4, realizing the secondary absorption of the near-infrared spectrum in the 900nm-1400nm band by the InGaAs bottom cell. At the same time, the bending stability of the AZO film and the internal stress of the Ta2O5 / SiO2 high reflective film self-compensate and adjust the warping, which is very suitable for the fabrication of flexible solar cells with PI film as flexible substrate.

[0044] Furthermore, the growth temperature of the AZO film 3 and the high-reflectivity film 4 is 150℃-180℃. This low-temperature growth process is compatible with PI film and is suitable for solar cells with PI film as a flexible substrate.

[0045] like Figure 7 This application also provides a triple-junction flexible solar cell prepared by the above-described method. From the back surface to the light-receiving surface, the solar cell sequentially comprises a flexible substrate 5, a high-reflectivity film 4, an AZO film 3, an epitaxial layer 2 of a flip-chip triple-junction solar cell, a positive electrode 8, and an anti-reflection film 10. The epitaxial layer 2, starting from the substrate, sequentially comprises a GaInP top cell, a GaAs middle cell, and an InGaAs bottom cell. The AZO film 3 is partially etched to serve as the back electrode 9. The high-reflectivity film 4 consists of multiple pairs of alternately stacked Ta2O5 and SiO2 layers. The high-reflectivity film 4 and the AZO film 3 form a back-reflection film structure. Its thickness, temperature, and other parameters, as well as the specific effects obtained, are as described above. This structure solves the problem of poor near-infrared spectrum absorption by the InGaAs bottom cell. Furthermore, the flexible substrate 5 is a PI film, and a Cr / Ti layer 6 and a SiO2 bonding layer 7 are sequentially stacked between the flexible substrate 5 and the high-reflectivity film 4. The SiO2 bonding layer 7 and the Cr / Ti layer 6 can form stress complementarity, effectively reducing the warpage and internal stress of the entire film stack. Furthermore, using SiO2 as the bonding medium to bond with the SiO2 layer in the high-reflectivity film results in a SiO2-SiO2 bonding structure. SiO2 is extremely stable under humid heat, ultraviolet light, and atomic oxygen conditions, preventing water vapor and ions from diffusing to the sensitive epitaxial layer. Moreover, the SiO2-SiO2 bonding structure replaces the traditional precious metal (such as Au-Au) hot-press bonding structure commonly used in flexible solar cells, not only saving expensive gold materials and simplifying the process but also avoiding the risk of metal ion contamination. Meanwhile, AZO, Ta2O5, and SiO2 are all common and environmentally friendly thin film materials, enabling this back-reflective film structure to possess high performance while also offering the advantages of low cost and green production, making it very suitable for large-scale industrial applications.

[0046] It is worth noting that the thicknesses of the GaAs substrate 1, epitaxial layer 2, AZO film 3, high-reflection film 4, flexible substrate 5, Cr / Ti layer 6, SiO2 bonding layer 7, positive electrode 8, back electrode 9, and anti-reflection film 10 shown in the accompanying drawings are merely examples and do not represent their actual thicknesses. Furthermore, the actual proportions between the GaAs substrate 1, epitaxial layer 2, AZO film 3, high-reflection film 4, flexible substrate 5, Cr / Ti layer 6, SiO2 bonding layer 7, positive electrode 8, back electrode 9, and anti-reflection film 10 are not as shown in the drawings and are for reference only.

[0047] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for fabricating a triple-junction flexible solar cell, characterized in that: From the back surface to the light-receiving surface of the solar cell, it consists of a flexible substrate, a high-reflection film, an AZO film, an epitaxial layer of the flip-chip triple-junction solar cell, a positive electrode, and an anti-reflection film. The epitaxial layer comprises, from the substrate, a GaInP top cell, a GaAs middle cell, and an InGaAs bottom cell in sequence. The AZO film and the high-reflectivity film form a back reflective film structure, and the portion of the AZO film exposed by etching serves as the back electrode. The high-reflectivity film is composed of multiple pairs of alternating stacked Ta2O5 layers and SiO2 layers. The refractive index of the Ta2O5 layer is 2.1 and the thickness is 140nm-150nm. The refractive index of the SiO2 layer is 1.46 and the thickness is 200nm-210nm. The number of alternating stacking periods of the Ta2O5 layer and SiO2 layer is 6-8 pairs. A Cr / Ti layer and a SiO2 bonding layer are sequentially stacked between the flexible substrate and the high-reflectivity film. The SiO2 bonding layer and the Cr / Ti layer form stress complementarity. The outermost layer of the high-reflectivity film near the flexible substrate is a SiO2 layer. The flexible substrate is bonded to the SiO2 layer in the high-reflectivity film through the SiO2 bonding layer.

2. The method for fabricating a triple-junction flexible solar cell as described in claim 1, characterized in that: The flexible substrate is a PI film, the AZO film is formed by electron beam evaporation at a temperature of 150℃-180℃, the high reflectivity film is formed by electron beam evaporation at a temperature of 150℃-180℃, and the bonding temperature between the SiO2 bonding layer and the SiO2 layer in the high reflectivity film is 150℃-180℃.

3. The method for fabricating a triple-junction flexible solar cell as described in claim 2, characterized in that: The AZO film is deposited at a temperature of 150°C, and the high-reflectivity film is deposited at a temperature of 150°C.

4. The method for fabricating a triple-junction flexible solar cell as described in claim 1, characterized in that: In the high-reflectivity film, the thickness of the Ta2O5 layer is 143 nm, the thickness of the SiO2 layer is 205 nm, and the number of alternating stacking periods of the Ta2O5 layer and the SiO2 layer is 6 pairs.

5. The method for fabricating a triple-junction flexible solar cell as described in claim 1, characterized in that: The thickness of the PI film is 50 μm.

6. The method for fabricating a triple-junction flexible solar cell as described in claim 1, characterized in that: The thickness of the AZO film is 80nm-120nm.

7. A method for fabricating a triple-junction flexible solar cell as described in claim 1 or 6, characterized in that: The thickness of the AZO film is 100 nm.

8. The method for fabricating a triple-junction flexible solar cell as described in claim 1, characterized in that: The AZO film is aluminum-doped zinc oxide.

9. The method for fabricating a triple-junction flexible solar cell as described in claim 1, characterized in that: In the Cr / Ti layer, the thickness of Cr is 30nm-60nm and the thickness of Ti is 50nm-100nm; the thickness of the SiO2 bonding layer is 500nm-1000nm.

10. The method for fabricating a triple-junction flexible solar cell as described in claim 1, characterized in that: The thickness of the SiO2 bonding layer is 500nm-1000nm.

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