A tandem stacked solar cell

Abstract

The application relates to the field of energy, and particularly provides a series connection laminated solar cell. The solar cell comprises, from left to right, a transparent electrode, an electron transport layer, a light absorption layer, a hole transport layer and a carbon electrode. The light absorption layer comprises a perovskite layer and a silicon layer, the perovskite layer is close to the electron transport layer, and the silicon layer is close to the hole transport layer. The transparent electrode, the electron transport layer, the perovskite layer, the silicon layer, the hole transport layer and the carbon electrode are fixedly connected. The application designs a light absorption layer with a non-single energy band structure in a series connection laminated mode, the light absorption layer is formed by laminating a perovskite layer and a silicon layer. When light is irradiated on the light absorption layer, the perovskite layer with a large energy band gap responds to a short wavelength band; the silicon layer with a small energy band gap responds to a long wavelength band; thereby the response wavelength of sunlight is widened, the absorption layer can absorb more photons, more electron-hole pairs are generated, and the conversion efficiency of solar energy into electric energy is improved.

Description

Technical Field

[0001] This application relates to the energy field, and more specifically, to a series-tandem solar cell. Background Technology

[0002] Solar cells can convert solar energy into electrical energy. Solar energy is inexhaustible, and the effective use of solar energy is an important means of solving energy problems.

[0003] A solar cell consists of a light-absorbing layer, a carrier transport layer, and electrodes. When sunlight shines on the light-absorbing layer, it absorbs the photon energy, generating electron-hole pairs. Under the influence of a built-in electric field, electrons and holes move towards opposite ends. Electrons pass through the electron transport layer to reach the negative electrode, and holes pass through the hole transport layer to reach the positive electrode. The positive and negative electrodes are connected to an external circuit for power supply. The light-absorbing layer has a simple band structure. When sunlight shines on the light-absorbing layer, only photons with wavelengths matching the band structure of the light-absorbing layer material can excite electrons from the valence band to the conduction band, thus generating electron-hole pairs. These electrons can then be further separated and migrated to the electrodes. In other words, photons with energy less than the band gap of the light-absorbing layer material cannot be utilized and do not contribute to the conversion process, resulting in low solar energy conversion efficiency.

[0004] In summary, the current solar cell has a simple band structure in its light-absorbing layer, resulting in low energy conversion efficiency. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by providing a series-mounted solar cell, thereby solving the problem of low energy conversion efficiency caused by the simple band structure of the light-absorbing layer in existing solar cells.

[0006] To achieve the above objectives, the technical solution adopted by this invention is as follows: This application provides a series-cascaded solar cell, which, from left to right, comprises a transparent electrode, an electron transport layer, a light-absorbing layer, a hole transport layer, and a carbon electrode. The transparent electrode and the carbon electrode are used to connect to an external circuit, the electron transport layer and the hole transport layer are used to transport electrons and holes, and the light-absorbing layer is used to absorb photon energy to generate electron-hole pairs. The light-absorbing layer includes a perovskite layer and a silicon layer, with the perovskite layer close to the electron transport layer and the silicon layer close to the hole transport layer. Light first passes through the perovskite layer with a larger band gap, causing photons with higher energy to be absorbed, and then passes through the silicon layer with a smaller band gap, causing photons with lower energy to be absorbed, thereby broadening the light response band and improving the energy conversion efficiency. The transparent electrode, electron transport layer, perovskite layer, silicon layer, hole transport layer, and carbon electrode are fixedly connected; the cell is prepared layer by layer using a deposition method or a spin-coating method. In this way, the perovskite layer and the silicon layer stack form a non-single band structure. When light shines on the light-absorbing layer, the perovskite layer with a larger band gap responds to the short wavelength band, while the silicon layer with a smaller band gap responds to the long wavelength band. This broadens the response wavelength of sunlight, and the absorption layer can absorb more photons and generate more electron-hole pairs, ultimately improving the conversion efficiency of solar energy into electrical energy.

[0007] Furthermore, the perovskite layer is made of CsPbX. a Y 3-a (X = I, Y = Br, a ≤ 3), the thickness of the perovskite layer is 300 nm-600 nm. CsPbX a Y 3-a The band gap (X=I, Y=Br, a≤3) is easy to adjust. The thickness of 300nm-600nm allows the perovskite layer to fully interact with sunlight, generating more electron-hole pairs; on the other hand, it allows more light fields to pass through the perovskite layer and interact with the silicon layer, generating electron-hole pairs in the silicon layer.

[0008] Furthermore, the silicon layer is made of silicon and has a thickness greater than 500 nm. Since the depletion region of the bulk silicon material is about 450 nm, the transmitted light field is almost zero, that is, all the light field is absorbed, thereby generating more electron-hole pairs in the silicon layer.

[0009] Furthermore, the hole transport layer is made of PEDOT:PSS, and the electron transport layer is made of TiO2 or SnO2.

[0010] Furthermore, the thickness of the electron transport layer is 50nm-80nm.

[0011] Furthermore, a silicon quantum dot layer is fixedly disposed between the perovskite layer and the silicon layer. In this way, the silicon quantum dots have strong quantum effects and a high surface defect density, which can capture hot carriers before cooling, reducing lattice heat loss caused when photon energy is higher than the band gap, thereby improving energy conversion efficiency.

[0012] Furthermore, the silicon quantum dot layer is formed by the stacking of silicon quantum dot particles.

[0013] Furthermore, the size of the silicon quantum dot particles ranges from 1 nm to 4.9 nm. Preferably, the size of the silicon quantum dot particles varies, as the size is closely related to their band gap. Silicon quantum dot particles of different sizes have different band gaps, corresponding to closer energy intervals between the conduction band and valence band. This allows photons over a wider spectral range to be absorbed, broadening the spectral range of the response and generating more electron-hole pairs. On the other hand, the closer band gaps form band groups, allowing multiple low-energy photons to work together to excite electrons from the valence band to the conduction band, generating a higher-energy electron-hole pair. In other words, photons that could not be absorbed before can participate in the conversion process, thereby improving the utilization rate of sunlight and increasing energy conversion efficiency.

[0014] Furthermore, the size of the silicon quantum dot particles closer to the perovskite layer is smaller than that of the silicon quantum dot particles closer to the silicon layer.

[0015] Furthermore, the transparent electrode is ITO or FTO.

[0016] Compared with the prior art, the beneficial effects of this invention are as follows: This application designs a light-absorbing layer with a non-single band structure through a series stacked layering method. The light-absorbing layer is formed by stacking a perovskite layer and a silicon layer. When light shines on the light-absorbing layer, the perovskite layer with a larger band gap responds to the short wavelength band, while the silicon layer with a smaller band gap responds to the long wavelength band. This broadens the response wavelength of sunlight, allowing the absorption layer to absorb more photons and generate more electron-hole pairs, thereby improving the conversion efficiency of solar energy into electrical energy. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a series-mounted solar cell provided by the present invention;

[0018] Figure 2 This is a partial schematic diagram of another series-stapled solar cell provided by the present invention.

[0019] Icons: 1-Transparent electrode; 2-Electron transport layer; 3-Perovskite layer; 4-Silicon layer; 5-Hole transport layer; 6-Carbon electrode; 7-Silicon quantum dot layer. Detailed Implementation

[0020] To make the implementation process of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings.

[0021] This invention provides a series-cascaded solar cell, such as... Figure 1 As shown, the solar cell, from left to right, comprises: a transparent electrode 1, an electron transport layer 2, a perovskite layer 3, a silicon layer 4, a hole transport layer 5, and a carbon electrode 6. Adjacent layers of the transparent electrode 1, electron transport layer 2, perovskite layer 3, silicon layer 4, hole transport layer 5, and carbon electrode 6 are fixedly connected and fabricated layer by layer using deposition or spin-coating methods, meaning the layers are fixed together through molecular or atomic interactions. The transparent electrode 1 is made of ITO or FTO. The electron transport layer 2 is made of TiO2 or SnO2; its thickness is 50nm-80nm. The perovskite layer 3 is made of CsPbX. a Y 3-a (X=I, Y=Br, a≤3); CsPbX a Y 3-a The band gap (X=I, Y=Br, a≤3) is easily adjustable. The thickness of the perovskite layer 3 is 300nm-600nm; this allows the perovskite layer 3 to fully interact with sunlight, generating more electron-hole pairs; on the other hand, it allows more light to pass through the perovskite layer 3 and interact with the silicon layer 4, generating electron-hole pairs in the silicon layer 4. The silicon layer 4 is made of silicon and has a thickness greater than 500nm; since the depletion region of bulk silicon is approximately 450nm, the transmitted light field is almost zero, meaning that all the light field is absorbed, thus generating more electron-hole pairs in the silicon layer 4. The hole transport layer 5 is made of PEDOT:PSS. The transparent electrode 1 and carbon electrode 6 are used to connect to the external circuit to provide power to the external circuit. The electron transport layer 2 and hole transport layer 5 are used to transport electrons and holes, and the perovskite layer 3 and silicon layer 4 are used to absorb photon energy to generate electron-hole pairs.

[0022] The perovskite layer 3 has a relatively large band gap of 1.7 eV-2.3 eV, while the silicon layer 4 has a smaller band gap of approximately 1.12 eV. The stacked perovskite layer 3 and silicon layer 4 form a non-single band structure. When light first strikes the perovskite layer 3 with its larger band gap, higher-energy photons are absorbed. Then, as the light passes through the silicon layer 4 with its smaller band gap, lower-energy photons are absorbed, thus broadening the light response wavelength and improving energy conversion efficiency. In other words, when light strikes the absorbing layer, the perovskite layer 3 with its larger band gap responds to shorter wavelengths, while the silicon layer 4 with its smaller band gap responds to longer wavelengths. This broadens the response wavelength of sunlight, allowing the absorbing layer to absorb more photons and generate more electron-hole pairs, ultimately improving the conversion efficiency of solar energy into electrical energy.

[0023] like Figure 2 As shown, a silicon quantum dot layer 7 is fixedly disposed between the perovskite layer 3 and the silicon layer 4. The silicon quantum dot layer 7 is formed by the stacking of silicon quantum dot particles. The size of the silicon quantum dot particles ranges from 1 nm to 4.9 nm. Since the Bohr radius of silicon is 4.9 nm, particles smaller than 4.9 nm exhibit a strong quantum confinement effect. The band gap is closely related to the size of the silicon quantum dots, resulting in a significant increase in surface defect density. These surface defects can trap hot carriers before cooling, reducing lattice heat loss when photon energy exceeds the band gap. Lattice heat loss leads to energy waste and reduced conversion efficiency; therefore, silicon quantum dots can improve energy conversion efficiency. Simultaneously, the silicon quantum dot layer 7 couples with the perovskite layer 3, allowing carriers to migrate between them. This lowers the Fermi level, increases the work function, and strengthens the built-in electric field, making electron-hole pair separation easier and improving photoelectric conversion efficiency.

[0024] The silicon quantum dot particles in silicon quantum dot layer 7 can be of the same or different sizes. Preferably, the silicon quantum dot particles are of different sizes, as the size of the silicon quantum dot particles is closely related to their band gap. Silicon quantum dot particles of different sizes have different band gaps, corresponding to a closer energy interval between the conduction band and the valence band. In this way, on the one hand, photons in a wider spectral range can be absorbed, broadening the response spectral range and generating more electron-hole pairs; on the other hand, the closer band gaps form band groups, allowing multiple low-energy photons to work together to excite electrons from the valence band to the conduction band, generating a higher-energy electron-hole pair. That is, photons that could not be absorbed before can participate in the conversion process, thereby improving the utilization rate of sunlight and increasing energy conversion efficiency.

[0025] More preferably, the size of the silicon quantum dot particles closer to the perovskite layer 3 is smaller than that closer to the silicon layer 4. The size of the silicon quantum dot particles closer to the perovskite layer 3 is 1 nm-3.5 nm; the size of the silicon quantum dot particles farther from the perovskite layer 3 is 3 nm-4.9 nm. Smaller size results in a larger band gap. Therefore, from the side closer to the transparent electrode 1 to the side farther away from the transparent electrode 1, the size of the silicon quantum dot particles gradually increases, and the corresponding band gap gradually decreases. This allows for a stepped conduction band and valence band distribution with the perovskite layer 3 and the silicon layer 4, enabling electrons and holes to gradually migrate to the transparent electrode 1 and the carbon electrode 6. Furthermore, this creates a wider band group, allowing multiple low-energy photons to work together to excite electrons from the valence band to the conduction band, resulting in a higher electron-hole pair ratio, thereby improving the utilization of sunlight and increasing photoelectric conversion efficiency.

[0026] like Figure 2As shown, nanoscale grooves are formed on the surface of the perovskite layer 3 near the silicon quantum dot layer 4, fabricated using micro-nano lithography or a template method. Specifically, the cross-sectional shape of the grooves can be rectangular, triangular, etc.; the opening size of the grooves is 200nm-500nm, and the depth is 50nm-100nm. This design facilitates the insertion of silicon quantum dots during fabrication. Furthermore, the grooves localize the light field, increasing the number of interactions between the light field at the grooves and the perovskite layer 3 and silicon quantum dot layer 4, resulting in more efficient interactions, more electron-hole pairs, and improved photoelectric conversion efficiency. Additionally, the increased contact area between the perovskite layer 3 and silicon quantum dot layer 4 strengthens the coupling effect, leading to greater carrier mobility, a more significant reduction in the Fermi level, a greater increase in the work function, a stronger built-in electric field, and higher electron-hole pair separation efficiency (i.e., a lower probability of electron-hole pair recombination), thus resulting in higher photoelectric conversion efficiency.

[0027] In application, sunlight shines from the transparent electrode 1. The light first illuminates the perovskite layer 3, which has a larger band gap, causing the higher-energy photons to be absorbed. Then, it passes through the silicon layer 4, which has a smaller band gap, causing the lower-energy photons to be absorbed. This broadens the light response wavelength and generates more electron-hole pairs. Under the influence of the built-in electric field, the electron-hole pairs are separated and pass through the electron transport layer 2 and the hole transport layer 5, reaching and accumulating at the transparent electrode 1 and the carbon electrode 6. The transparent electrode 1 and the carbon electrode 6 are used to connect to an external circuit to provide power. In other words, when light shines on the light-absorbing layer, the perovskite layer 3, with its larger band gap, responds to short-wavelength bands; the silicon layer 4, with its smaller band gap, responds to long-wavelength bands. This broadens the response wavelength of sunlight, allowing the absorption layer to absorb more photons and generate more electron-hole pairs, ultimately improving the conversion efficiency of solar energy into electrical energy. Simultaneously, silicon quantum dots are introduced to improve photoelectric conversion efficiency. Specifically, the reasons are as follows: Firstly, the surface defect density is significantly increased, allowing surface defects to capture hot carriers before cooling, reducing lattice heat loss when photon energy exceeds the band gap. Lattice heat loss leads to energy waste and reduced conversion efficiency; therefore, silicon quantum dots improve energy conversion efficiency. Secondly, the coupling between silicon quantum dot layer 7 and perovskite layer 3 allows carriers to migrate between them, lowering the Fermi level, increasing the work function, and strengthening the built-in electric field. This facilitates electron-hole pair separation, improving photoelectric conversion efficiency. Thirdly, the closer band gaps form a band group, allowing multiple low-energy photons to work together to excite electrons from the valence band to the conduction band, generating a higher-energy electron-hole pair. This allows photons that were previously unabsorbable to participate in the conversion process, improving the utilization of sunlight and increasing energy conversion efficiency. Therefore, this application's solar cell improves energy conversion efficiency by changing the band structure.

[0028] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A series-cascaded solar cell, wherein the solar cell comprises, from left to right, a transparent electrode, an electron transport layer, a light-absorbing layer, a hole transport layer, and a carbon electrode, characterized in that, The light-absorbing layer includes a perovskite layer and a silicon layer. The perovskite layer is close to the electron transport layer, and the silicon layer is close to the hole transport layer. The transparent electrode, the electron transport layer, the perovskite layer, the silicon layer, the hole transport layer, and the carbon electrode are fixedly connected. A silicon quantum dot layer is fixedly disposed between the perovskite layer and the silicon layer. The silicon quantum dot layer is formed by the accumulation of silicon quantum dot particles, and the size of the silicon quantum dot particles on the side closer to the perovskite layer is smaller than the size of the silicon quantum dot particles on the side closer to the silicon layer.

2. The series-tandem solar cell according to claim 1, characterized in that, The perovskite layer is made of CsPbX. a Y 3-a (X=I, Y=Br, a≤3), the thickness of the perovskite layer is 300 nm-600 nm.

3. The series-connected tandem solar cell according to claim 2, characterized in that, The silicon layer is made of silicon and has a thickness greater than 500 nm.

4. The series-tandem solar cell according to claim 3, characterized in that, The hole transport layer is made of PEDOT:PSS, and the electron transport layer is made of TiO2 or SnO2.

5. The series-tandem solar cell according to claim 4, characterized in that, The thickness of the electron transport layer is 50 nm-80 nm.

6. The series-tandem solar cell according to claim 5, characterized in that, The silicon quantum dot particles have a size of 1 nm to 4.9 nm.

7. The series-tandem solar cell according to claim 1, characterized in that, The transparent electrode is ITO or FTO.

Images