A transparent solar cell device

Abstract

This invention relates to a transparent solar cell device, comprising a front substrate, a transparent positive electrode layer, a PV photovoltaic layer, a transparent or semi-transparent negative electrode layer, and a back cover stacked together. The inner surface of the back cover has a focusing structure. The focusing structure can be fabricated by bulk etching, coating, or nanoimprinting. The surface pattern of the focusing structure can be a regular tetrahedron, a regular or irregular hemisphere, a cone, a trapezoid, a triangle, or a strip or block structure with a smooth convex cross-section. The height of the focusing structure is 20 nm to 2000 nm. With the focusing structure on the back cover, light incident from outside the device is refracted multiple times by the focusing structure and then incident in a direction tending to be perpendicular to the device surface. It sequentially enters the transparent or semi-transparent cathode layer, ETL, and photovoltaic active layer. In the photovoltaic active layer, excitons are absorbed and generated, and electrons and holes are separated at the donor-acceptor interface, improving the utilization of incident light and thus increasing the photoelectric efficiency of the solar cell device.

Description

Technical Field

[0001] This invention belongs to the field of product design and manufacturing technology of solar cell devices, and particularly relates to a transparent solar cell device. Technical Background

[0002] Currently, with consumers increasingly relying on various wearable, portable, and handheld electronic devices, the power consumption of these devices has become a prominent issue. Low power consumption, high battery capacity, and fast charging solutions have become problems that developers are racking their brains to solve. In addition, designers are gradually recognizing the need to equip electronic devices with external, sustainably powered devices, including but not limited to the development of photovoltaic (solar cell) and thermoelectric power generation devices, which are becoming mainstream in electronic product design. Regarding solar photovoltaic devices, considering that in practical applications they may need to cover the upper surface of the effective display area of ​​a monitor or a surface where the background needs to be highlighted, when electronic products need to incorporate external solar cells, it is necessary to consider making the solar cells transparent or semi-transparent. However, transparent or semi-transparent devices have lower photoelectric conversion efficiency, so there is an urgent need to develop a transparent solar cell device with improved photoelectric conversion efficiency. Summary of the Invention

[0003] This invention addresses the shortcomings of the prior art. Specifically, the technical problem this invention aims to solve is to fabricate a transparent solar cell device with a transmittance of 50% to 80% in the visible light (400nm–700nm) range, but with a power generation efficiency of less than 6%. The improved device achieves a power generation efficiency of over 10%.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is: a transparent solar cell device, comprising: a front substrate, a transparent positive electrode layer, a PV photovoltaic layer, a transparent or semi-transparent negative electrode layer, and a back cover stacked together, wherein a light-concentrating structure is provided on the inner surface of the back cover; the light-concentrating structure can be fabricated by body etching, coating, or nanoimprinting, and the surface pattern of the light-concentrating structure is a regular tetrahedron, a regular or irregular hemisphere, a cone, a trapezoid, a triangle, or a strip or block structure with a smooth convex cross-section; the height of the light-concentrating structure is 20nm to 2000nm.

[0005] As a preferred technical solution, the outer surface of the back cover is provided with an anti-reflection coating to further improve the utilization rate of incident light.

[0006] As a preferred technical solution, the light-concentrating structure is a transparent material with a refractive index greater than or equal to that of the back cover body.

[0007] As a preferred technical solution, transparent solar cell devices are either monochromatic or multicolor transparent.

[0008] As a preferred technical solution, the front substrate is a colorless and transparent rigid or flexible substrate; when the front substrate is a flexible substrate, one or more water vapor barrier optical film layers are provided on the surface of the flexible substrate.

[0009] As a preferred technical solution, the moisture-blocking optical film is made of one or more combinations of silicon nitride, silicon oxide, silicon oxynitride, and organic resin coating, and is disposed on one or both sides of the front substrate.

[0010] As a preferred technical solution, it also includes a frame adhesive for bonding the front substrate and the rear cover together. The frame adhesive is a UV-curable, thermosetting, or a combination of both resins. The frame adhesive is filled with water and oxygen adsorption particles and spacers with uniform particle size. The spacers have a particle size of 2 to 100 μm and are made of resin or silicon dioxide.

[0011] As a preferred technical solution, a liquid or solid desiccant is provided on the inside of the back cover.

[0012] As a preferred technical solution, the desiccant is made of a transparent or opaque material; when the desiccant is made of an opaque material, it is located outside the effective absorption area of ​​the PV photovoltaic layer; when the desiccant is made of a transparent material, its refractive index is less than or equal to the refractive index of the light-concentrating structure provided on the inner surface of the back cover.

[0013] As a preferred technical solution, the transparent positive electrode layer is made of PEDOT:PSS with a conductivity of ≥800S / cm and a thickness of 100~2000nm.

[0014] This invention achieves the following technical advantages over existing technologies: It proposes a transparent solar cell device with a focusing structure on its back cover. Light incident from outside the device undergoes multiple refractions through this structure, then enters the transparent or semi-transparent cathode layer, ETL layer, and photovoltaic active layer sequentially. Excitons are absorbed in the photovoltaic active layer, and electrons and holes are separated at the donor-acceptor interface. This improves the utilization of incident light, thereby increasing the photoelectric efficiency of the solar cell device. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a monochromatic solar cell device provided in an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the structure of a multicolor solar cell device provided in an embodiment of the present invention;

[0017] Figure 3This is a schematic diagram of a light-concentrating structure provided in an embodiment of the present invention;

[0018] Figure 4 This is a schematic diagram illustrating the working principle of the light-concentrating structure provided in an embodiment of the present invention;

[0019] Explanation of reference numerals in the attached figures

[0020] 1. Front substrate; 2. Moisture barrier optical film layer; 3. Transparent positive electrode layer; 4. HTL41; 4. ACT-L42; 4. ETL43; 5. Transparent or semi-transparent negative electrode layer; 6. Light-concentrating structure; 7. Frame adhesive; 8. Spacer; 9. Desiccant; 10. Anti-reflective coating; 11. Back cover. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] In the description of this invention, it should be understood that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Example

[0024] like Figure 1 The diagram shown is a structural schematic of a monochromatic solar cell device provided in an embodiment of the present invention. The solar cell device includes a front substrate 1, a transparent positive electrode layer 3, a PV photovoltaic layer, a transparent or semi-transparent negative electrode layer 5, and a back cover 11 stacked together.

[0025] The PV photovoltaic layer includes a basic three-layer structure: HTL41 (hole transport layer), ACT-L42 (photovoltaic active layer), and ETL43 (electron transport layer).

[0026] The material of the back cover 11 encapsulation material includes, but is not limited to, rigid (such as glass, quartz, etc.) or flexible (such as CPI, PET, PC, COP, COC, PMMA, etc.) colorless and transparent film (t≤0.15mm).

[0027] Preferably, the inner surface of the back cover 11 is provided with a light-concentrating structure 6. The light-concentrating structure 6 is a transparent material with a refractive index greater than or equal to the refractive index of the back cover 11 body.

[0028] like Figure 3 The diagram shows a schematic of the focusing structure 6. The focusing structure 6 can be fabricated using methods such as bulk etching, coating, and nanoimprinting. The surface pattern of the focusing structure 6 can be a tetrahedron, a regular or irregular hemisphere, a cone, a trapezoid, a triangle, or a semicircular strip-shaped structure in the form of straight lines or curves. When the focusing structure 6 is fabricated using bulk etching, the surface pattern can include, but is not limited to, the aforementioned structures; it can also be an irregular hemispherical shape or a strip or block with a smooth convex cross-section. Furthermore, the height of the focusing structure 6 is 20 nm to 2000 nm.

[0029] like Figure 4 The diagram shown illustrates the working principle of the light-concentrating structure 6 provided in an embodiment of the present invention. Let the incident angle be α, the reflection angle be β, and the refraction angle be θ.

[0030] The light-collecting structure 6 (Lens) is an optically dense medium with a refractive index of n3. The back cover 11 is also an optically dense medium with a refractive index of n2. Furthermore, n3 ≥ n2.

[0031] When light enters the back cover 11 from the air, according to the law of refraction, n1*Sinα=n2*Sinθ, since n1<n2, it can be deduced that the angle of incidence is greater than the angle of refraction (i.e., α>θ).

[0032] As light continues to be incident from the back cover 11 into the light-concentrating structure 6, according to the law of refraction n2*Sinα'=n3*Sinθ', since n2≤n3, it can be deduced that the incident angle is greater than or equal to the refraction angle (i.e., α'≥θ').

[0033] As light continues to enter the device cavity from the focusing structure 6, according to the law of refraction:

[0034] Since n3*Sinα"=n4*Sinθ", and n3>n4, it can be deduced that the incident angle is smaller than the refraction angle (i.e., α"<θ). As shown in the figure, after multiple refractions, the incident light enters the transparent or semi-transparent cathode layer, ETL43, and photovoltaic active layer sequentially, where it is absorbed to generate excitons. At the donor-acceptor interface, electrons and holes are separated. This improves the utilization of the incident light, thereby increasing the photoelectric efficiency of the solar cell device.

[0035] Preferably, the outer surface of the back cover 11 is provided with an anti-reflection coating 10 to further improve the utilization rate of incident light.

[0036] Preferably, the transparent solar cell device can be a single-color transparent device or a multi-color transparent device. Figure 1 The diagram shown is a schematic of a monochrome transparent device. Figure 2 A schematic diagram of the structure of a multicolor transparent device is then given.

[0037] In OPV-type solar cells, the active layer (ACT-L42) is made of polymer donor materials (P3HT, PM6, PTZDI, etc.) and polymeric or macromolecular acceptor materials (PCBM, Y6, DTY6, etc.). The active layer of perovskite solar cells can be a simple inorganic perovskite (ABX3 type, A2BB type). ’ (e.g., X6 type) can also be an organic-inorganic hybrid perovskite battery. Different combinations of active layers can yield different transparency colors and electrical properties for the same type of battery.

[0038] Those skilled in the art should be able to conceive that, using patterning processes, monochrome transparent devices can be fabricated, such as those in red, green, blue, purple, and magenta, and multi-color combinations can be created, such as combinations of two or more colors from red, green, blue, purple, and magenta. When fabricating multi-color combinations, the same HTL41 (hole transport layer) and ETL43 (electron transport layer) layers are shared, and different combinations of donor and acceptor materials are coated in stages according to the type of material combination, or a multi-head Ink-jet device is used to correspond to different color combinations of materials. Because the properties of the active layer materials in different systems differ, the structural design of the devices differs.

[0039] Preferably, the HTL41 of the OPV solar cell is generally made of P3HT, PTAA, Spiro-OMeTAD, PEDOT:PSS, etc. (the resistivity after film formation is in the range of 500 to 5000 Ω·cm), and the film thickness is in the range of 40 nm to 80 nm. Preferably, the film thickness is 50 nm.

[0040] When the transparent positive electrode is made of highly conductive PEDOT:PSS material, the total film thickness is adjusted to 100–2000 nm. In this case, the structure can serve as both the transparent positive electrode layer 3 and the HTL41 in the PV photovoltaic layer, eliminating the need for a separate HTL41 fabrication. However, considering the energy level matching issue between the transparent positive electrode layer 3 and ACT-L42, it is preferable to perform a special processing step on the PEDOT:PSS film after deposition. Those skilled in the art should be able to conceive of special processing steps including, but not limited to, solvent annealing, plasma treatment, UV light treatment, or acid and alkali washing. The solvent annealing process preferably uses polar solvents (water and lower alcohols, etc.), and is combined with ultrasonic cleaning to treat the highly conductive PEDOT:PSS, reducing the resistivity of the outermost layer (approximately 50–100 nm) to 500–5000 Ω·cm. At this point, the energy level of the outermost layer is more closely matched with the energy level of the photovoltaic active layer. When using plasma treatment, oxygen plasma should be avoided in OPV and DSC type solar cells, as it can easily introduce oxygen atoms at the active layer interface, causing excitons in the active layer to be quenched by oxygen atoms. When using UV light or laser treatment, the wavelength λ of the UV light or laser should be ≤280nm, and the ozone content generated during the treatment process should be appropriately reduced. This approach should be avoided in OPV and DSC type solar cells to prevent the introduction of oxygen atoms at the active layer interface, which could cause excitons in the active layer to be quenched by oxygen atoms. The materials selected for acid washing or alkali washing processes are generally weakly acidic or weakly alkaline materials, preferably organic weak acids (acetic acid, oxalic acid, lactic acid, etc.) or organic weak bases (mixtures of TMAH, diethylene glycol, and ether with a volume concentration of less than 4%). HTL41 for perovskite solar cells includes the aforementioned organic HT materials, and can also be Cu2O, CuI, CuSCN, NiO, etc.

[0041] Preferably, the ETL43 of the OPV battery can be made of small molecule materials or polymer materials. Small molecule compounds are generally fabricated by vapor deposition, including aromatic amine compounds, alkali metal compounds, etc.; polymers are generally fabricated by solution methods, including but not limited to fullerenes and their derivatives (PC). 60 BM, PC 61 BM, PC 71 BM, etc.), PCBA, ICBA, PFN, Bis-C 60 ETL43 for perovskite solar cells includes the aforementioned organic ETL43 materials as well as inorganic materials such as TiO2 and ZnO.

[0042] The front substrate 1 is a colorless and transparent rigid or flexible substrate. The rigid substrate can be made of glass or thick (t≥0.3mm) PC board, PET board, etc., while the flexible substrate can be a colorless and transparent film (t≤0.15mm) such as CPI, PET, PC, COP, COC, PMMA, etc. During the manufacturing process, this type of flexible substrate generally requires a rigid substrate as a base. After completing all processes, it is peeled off from the surface of the rigid substrate without damage. When the front substrate 1 is a flexible substrate, preferably, one or more water vapor barrier optical film layers 2 are provided on the surface of the flexible substrate.

[0043] Preferably, the moisture-blocking optical film layer 2 is made of one or more combinations of silicon nitride, silicon oxide, silicon oxynitride, and organic resin coating, and is disposed on one or both sides of the front substrate 1. When it is only fabricated on the inner surface of the front substrate 1, the surface where the moisture-blocking optical film layer 2 is located is in contact with the transparent positive electrode layer.

[0044] Preferably, the transparent positive electrode layer 3 can be made of TCO (transparent conductive oxide), nano silver, carbon nanotubes, graphene, ultrathin metal layers (such as magnesium-silver alloy layers), or directly using high-conductivity PEDOT:PSS material (conductivity ≥800S / cm).

[0045] Preferably, the transparent or semi-transparent negative electrode layer 5 can be made of TCO (transparent conductive oxide), nano-silver, carbon nanotubes, graphene, an ultrathin metal layer (such as a magnesium-silver alloy layer), or directly using a high-conductivity PEDOT:PSS material (conductivity ≥ 800 S / cm). Preferably, the work function of the transparent or semi-transparent negative electrode layer 5 material is lower than that of the transparent positive electrode layer 3 material to facilitate electron transport.

[0046] Preferably, it also includes a frame adhesive 7 for bonding the front substrate 1 and the rear cover 11 together. The frame adhesive 7 is a UV-curable, thermosetting, or a combination of both resins. The frame adhesive 7 is filled with water and oxygen adsorption particles and Spacer 8 with uniform particle size. The Spacer 8 has a particle size of 2 to 100 μm and is made of resin or silicon dioxide.

[0047] Preferably, a liquid or solid desiccant 9 is provided on the inner side of the back cover 11. The desiccant 9 does not contact the transparent or translucent negative electrode layer 5, or the desiccant 9 can contact the transparent or translucent negative electrode layer 5, but will not undergo a chemical reaction during storage and operation. The desiccant 9 can be made of transparent or opaque material; when the desiccant 9 is opaque, it is located outside the effective absorption area of ​​the PV photovoltaic layer; when the desiccant 9 is transparent, its refractive index is less than or equal to the refractive index of the light-concentrating structure 6 provided on the inner surface of the back cover 11. The purpose of providing the desiccant 9 is to more effectively extend the life of the device.

Claims

1. A transparent solar cell device, characterized by, It comprises: A front substrate, a transparent positive electrode layer, a PV photovoltaic layer, a transparent or semi-transparent negative electrode layer, and a back cover arranged in a stack, wherein the inner surface of the back cover is provided with a light condensing structure; the light condensing structure is made of a transparent material with a refractive index n3 greater than the refractive index n2 of the body of the back cover; The light condensing structure is configured so that the incident light is refracted by the back cover and the light condensing structure in multiple layers, and then enters the device cavity in a direction tending to be perpendicular to the surface of the device, wherein the height of the light condensing structure is 20nm-2000nm; The light condensing structure can be made by body etching, coating, or nano-imprinting, and the surface pattern type of the light condensing structure is a regular tetrahedron, a regular or irregular cone, a trapezoidal, a triangular strip structure, or a block structure; The outer surface of the back cover is provided with an anti-reflection coating to further improve the utilization rate of incident light; The front substrate is a colorless and transparent flexible substrate; when the front substrate is a flexible substrate, one or more water vapor barrier optical film layers are provided on the surface of the flexible substrate; It also includes a frame glue for bonding the front substrate and the back cover together, the frame glue is a UV-curable or heat-curable resin or a combination of both; the frame glue is filled with water and oxygen adsorption particles and a Spacer with uniform particle size, the particle size of the Spacer is 2-100μm, and the material of the Spacer is resin or silicon dioxide; The inner side of the back cover is provided with a liquid or solid desiccant; the desiccant is a transparent material, and when the desiccant is a transparent material, its refractive index is less than the refractive index of the light condensing structure provided on the inner surface of the back cover, and the material of the transparent positive electrode layer is PEDOT:PSS with an electrical conductivity of ≥800S / cm and a thickness of 100-2000nm.

2. The transparent solar cell device according to claim 1, wherein The transparent solar cell device is a single-color transparent or multi-color transparent device.

3. The transparent solar cell device according to claim 1, wherein The material of the water vapor barrier optical film layer is a combination of one or more of silicon nitride, silicon oxide, silicon oxynitride, and organic resin coating, which is provided on one side or both sides of the front substrate.

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