Description:Field of the Invention
[0001] The present invention relates to a highly efficient heterojunction solar cell containing silicon materials. The invention more particularly relates to solar cell in industrial sectors.
Background
[0002] The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Generally, Photovoltaic solar cell is crystalline silicon material. Crystalline silicon is abundant, non-toxic, low-cost, allows the fabrication of cells with high and stable conversion efficiency, is the most mature photovoltaic material, and is the long-term market leader. There is very widespread and deep skill and infrastructure available in crystalline silicon technology, both within the photovoltaic and integrated circuit industries.
[0004] Thousands of researchers and companies work in the area of crystalline silicon, feeding their capabilities into the manufacture of crystalline silicon materials, cells and modules. Problems and opportunities that arise rapidly come to the attention of many skilled people and companies, leading to commercial solutions. Companies innovate rapidly, creating machines that can implement in a commercial setting improvements obtained in laboratories. Crystalline silicon photovoltaic modules that meet certification requirements are widely trusted to perform as expected for decades. Crystalline silicon modules have substantially higher efficiency than any non-concentrating modules on the market, which reduces the cost of the area-related balance of systems components. As the cost of the modules declines, the latter becomes a dominant cost of photovoltaic electricity.
[0005] Many analysts expect the past and present domination of the photovoltaic market by crystalline silicon technology to continue into the indefinite future. There are various techniques & methods to resolve regarding this problem, which are disclosed in patent literature. Few exemplary documents are discussed below.
[0006] The US009842949B2 (by: M. Moslehi et al, (US)) relates to various embodiments disclosed herein describe a fabrication methods and structures relating to backplanes for back contact solar cells that provide for solar cell substrate reinforcement and electrical interconnects as well as Fabrication methods and structures for forming thin film back contact solar cells are described.
[0007] The US010526538B2 (by: Maria Faur, North Olmsted, OH (US); Horia M. Faur, Medina, OH (US)) relates to disclosed is a method, process, solar cell design, and fabrication technology fir high efficiency, low cost, crystal line silicon (Si) solar cells including but not restricted to solar grade single crystal Si (c-Si ), multi crystalline Si (mc-Si ), poly-Si, and micro-Si solar cells and solar modules. The RTWCG solar cell fabrication technology creates a RTWCG SiOx thin film antireflection coating (ARC) with a graded index of refraction and a selective emitter (SE). The resulting top surface of the SiOx oxide can be textured (TO) concomitant with the growth process or through an additional mild wet chemical step.
[0008] To US010593822B2 (by: Jolywood (Suzhou) Sunwatt Co., Ltd., Jiangsu ( CN )) relates to the field of solar cells, and in particular to a main-gate-free and high efficiency back contact solar cell module, a main-gate-free and high efficiency back-contact solar cell assembly , and a preparation process thereof. The solar cell module, comprising cells and an electrical connection layer, a backlight side of the cells having P-electrodes connected to a P-type doping layer and N-electrodes connected to a N-type doping layer , is characterized in that the electrical connection layer comprises a number of parallel leads each electrically connected to the P-electrodes or the N-electrodes. The present invention has the beneficial effect that a main-gate-free and high - efficiency back-contact solar cell module, a main - gate - free and high efficiency back-contact solar cell assembly, and a preparation process thereof are provided , which can effectively the short - circuiting of the P- electrodes and the N- electrodes and has the advantages of low cost, high hidden- cracking resistance, high efficiency and high stability.
[0009] The US 20210343890A1 (by: Mikko VAANANEN, Helsinki (FI)) relates to an invention belongs to the methods and apparatus for improving the power generated, and thus efficiency of solar cells, a double or triple junction tandem solar cell that has one or two photon filters of the invention in between the solar cell layers, respectively. The photon filter is arranged to reflect photons with wave length shorter than ?x and arranged to be transparent to photons of wavelength longer than ?x by focussing the lower energy photons out of small area apertures on the other side of the photon filter and arranging the other side of the photon filter to reflect at least some of the photons of wavelength longer than ?x. By using the photon filters of the invention in between the solar cell layers, photons can be trapped between filters to solar cell layers at an energy at which the quantum efficiency of the solar cell layer is the best.
[00010] The 202321078514 (Sagar Ramdas Sonawane et al, Pune, India) invention is based on heat transfer and converted into electricity Principle. The main purpose of this Innovation is generating the electricity by heat which is come from the sun. In India the lots of solar energy is available in every season but we cannot fully utilized this energy. In other hand the consumption of electricity is more because increase in population, modernization, industrialization and living of standard of people. In worldwide, the use of electricity is very much higher and similarly requirement of generation of electricity is increased day by day. So demand of electricity become more and more. The lot of amount government spends on electricity generation. The main aim of our work is to produce low-cost electricity and to achieve economy for society. In this work construct a solar panel which produce electricity after heating up. In experiment, the Aluminum panel 1000mm x 600mm x 0.2mm size and a solar cell consist of black glass panel winded with 0.2mm dia. Copper wire. All solar cell and four thermoelectric power generators are fixed over the aluminum panel and each solar cell copper wire is connected to each other one by one in series to form a complete circuit. Also the thermoelectric power generators are connect each other as well as connect to the first and last end of copper wire cicrcuit. This complete unit form a solar panel. This complete circuit is attached to solar charge controller to measure voltage produced in the solar panel. This solar panel is exposed to sunlight and whole panel heated up because heat is absorbed by aluminum panel, glass and copper wire. This heat in the panel transferred through copper wire and thermoelectric power generator to the solar charge controller. The electricity produced in solar panel is measures after one hour time interval. This Whole unit panel produced electricity at the rate of 20V but when solar panel temperature is goes above 800C then the rate of volt supply (Heat transfer) from panel is decreased.
[00011] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
Objects of the Invention
[00012] The principal object of the present invention is to overcome the disadvantages of the prior art.
[00013] Another object of the present invention is to provides a highly efficient heterojunction solar cell using silicon materials.
[00014] Another object of the present invention is that the efficiency of back junction Silicon heterojunction (SHJ) solar cells improved with back contacts consisting of p-type doped nanocrystalline silicon and a transparent conductive oxide with a low sheet resistance.
[00015] Yet, still another object of the present invention is to obtain a high-power conversion efficiencies and fill factors.
Summary
[00016] The present invention relates to a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention.
[00017] In an aspect, the present invention provides a highly efficient heterojunction solar cell using silicon materials. It also provides a high-power conversion efficiencies and fill factors.
[00018] Generally, Photovoltaic solar cells are one of the main renewable energy sources. Wafer-based crystalline silicon (c-Si) solar cells are the dominant technology in the global photovoltaic (PV) market. Aiming at a higher power efficiency, technology iteration is occurring from the passivated emitter and rear cell (PERC) to tunnel oxide passivated contact (TOPCon) and silicon heterojunction (SHJ) solar cells.
[00019] Silicon heterojunction technology employs an p-type (p-type) doped hydrogenated amorphous silicon (a-Si:H) layer, called n-a-Si: H (p-a-Si: H), as the electron-selective contact layer (ESC)–hole-selective contact layer (HSC). This overlays the intrinsic hydrogenated amorphous silicon (i-a-Si:H) layer, providing high-quality chemical passivation and minimizing the deficit in open circuit voltage. The electrical performance of the solar cells depends strongly on the net doping of both the ESC and HSC layers.
[00020] In another aspect, the present invention provides a sufficiently high doping concentration produces favourable band bending, allowing holes (minority carriers) to tunnel (selective collection of holes); efficient field-effect passivation, repelling electrons from the interface and mitigating the resulting interface recombination; and a reduced energy barrier when directly in contact with the n-type transparent conducting oxide (TCO). However, doped a-Si:H layers are always limited by unsatisfying electrical conductivity and relatively high activation energy (Ea?>?250?MeV), which cause high contact resistivity in SHJ solar cells.
[00021] In another aspect, In contrast to defect-rich amorphous silicon, hydrogenated nanocrystalline silicon (nc-Si:H) dramatically improves film crystallinity, which straight forwardly favours the improvement of carrier mobility and effective doping concentration. However, depositing a sufficiently thin layer of highly crystalline nc-Si:H on amorphous surfaces at low temperature is challenging. Depositing p-type doped nc-Si:H (p-nc-Si:H) is even more difficult, as boron doping restricts grain growth.
[00022] In another aspect, a high crystalline volume fraction (XC)—up to 50%—has been recorded through fine tuning gas flow rates. In this invention it`s concluded that surface coalescence of the p-nc-Si:H nanocrystals, rather than doping concentration, dominantly determines the activation energy Ea of the film. The hole selectivity and hole transport through the TCO–p-nc-Si:H contact the solar cell’s VOC and fill factor (FF) are crucially influenced by the electrical contact properties between TCO and the crystalline phase at the surface of the p-nc-Si:H layer. Based on this understanding, the contact resistivity of p-nc-Si:H-based HSCs has been reduced to about 100?m??cm2, yielding a series resistance (RS) of 0.65– 1.3???cm2 and a 23–25% power conversion efficiency (PCE).
[00023] In another aspect, a nano crystallization processes for fabricating cutting-edge HSCs, which—when paired with correspondingly tailored TCO—result in improved PCEs and FFs on wafer-scale single-junction SHJ solar cells. The present invention demonstrates a 26.30% SHJ solar cell with an FF of 86.59%; to the best of our knowledge, this FF outperforms any other silicon solar cell. By reducing the shading ratio from 2.8 to 2.0% and modifying the window layers at the front to minimize the parasitic absorption, it boosts the PCE to 26.74% by increasing the short-circuit current density (JSC) to 41.16?mA?cm-2. Also, by introducing an additional reflective MgF2/Ag stack at the rear side and regulating the transmittance of TCO of the present structure, a PCE of 26.81% with a JSC of 41.45?mA?cm-2 has been achieved. So finally, the proposed device attains a high-power efficiency 26.81 and fill factor 86.59% using Silicon heterojunction solar cell.
[00024] Various computer programs, mathematical tools, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which numerals represent like components.
Brief Description of the Drawings
[00025] Fig. 1 illustrates an exemplary system to design a silicon heterojunction solar cell in accordance with the embodiments of the present disclosure.
Detailed Description
[00026] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive blocks, the inventive subject matter is considered to include all possible combinations of the disclosed elements.
[00027] Fig. 1 illustrates an exemplary system containing a heterojunction solar cell with silicon materials 100. In this structure power conversion efficiency (PCE) technology iteration is occurring from the passivated emitter and rear cell (PERC) to tunnel oxide passivated contact (TOPCon) and silicon heterojunction (SHJ) solar cells. SHJ technology employs an n-type (p-type) doped hydrogenated amorphous silicon (a-Si:H) layer, called n-a-Si:H (p-a-Si:H), as the electron-selective contact layer (ESC)–hole-selective contact layer (HSC). This overlays the intrinsic hydrogenated amorphous silicon (i-a-Si:H) layer 104, providing high-quality chemical passivation and minimizing the deficit in open circuit voltage (VOC).
[00028] In an embodiment, a sufficiently high doping concentration produces favourable band bending, allowing holes (minority carriers) to tunnel (selective collection of holes); efficient field-effect passivation, repelling electrons from the interface and mitigating the resulting interface recombination; and a reduced energy barrier when directly in contact with the n-type transparent conducting oxide (TCO) 102.
[00029] In an embodiment, In contrast to defect-rich amorphous silicon, hydrogenated nanocrystalline silicon (nc-Si:H) dramatically improves film crystallinity, which straightforwardly favours the improvement of carrier mobility and effective doping concentration. Hole selectivity and hole transport through the TCO–p-nc-Si:H 107 contact and hence, the solar cell’s VOC and fill factor (FF) are crucially influenced by the electrical contact properties between TCO and the crystalline phase at the surface of the p-nc-Si:H layer.
[00030] In an embodiment, SHJ solar cells feature greater electrical performance measured by VOC?×?FF, while TOPCon 101 and PERC hold relatively superior JSC. The inferior JSC of SHJ solar cells can be attributed to the strong parasitic absorption inherent in the functional layers at the front side; PERC and TOPCon usually yield higher JSC (>41?mA?cm-2) due to the use of conventionally diffused front junctions and optically transparent antireflective coatings. Benefiting from the unique design of rear-sided passivating contact with an SiOx/poly-Si(n+) stack, TOPCon wins out over PERC with intrinsically improved VOC. SHJ produces the highest VOC among the c-Si solar cell technologies because of the excellent surface passivation provided by the i-a-Si:H layers 104 & 104a.
[00031] In an embodiment, the performance of SHJ solar cells has increased almost linearly both electrically and optically. The first SHJ solar cell from our group (LONGi) delivered a PCE of 25.26%, and now further boosted all the PV parameters. In this invention, we show a PCE of 26.81%, with VOC of 751.4?mV (an improvement of 2.9?mV), FF of 86.07% (0.57% improvement) and JSC of 41.45?mA?cm-2 (an improvement of 1.97?mA?cm-2), an overall efficiency gain of 1.55%. Note that we achieved the highest FF of 86.59% on a different device: that is, the cell delivering an efficiency of 26.30%.
[00032] In an embodiment, the main contributions to the efficiency increase, two related designs with p-a-Si:H (cell 1, 25.26% PCE) and p-nc-Si:H (cell 2, 26.30%) serving as the rear emitter are investigated in the proposed invention. The two devices are in a front and back contact architecture on an n-type c-Si (n-Si) wafer with front-sided n-type nanocrystalline silicon oxide (n-nc-SiOx:H) and a back junction (BJ). Using BJ structure alleviates the electrical requirements on the front-side TCO and metal electrodes since a large portion of the majority carriers (electrons) can be laterally collected via the n-Si 105 wafer absorber. The main difference between the two solar cells comes from the BJ stacks; the p-nc-Si:H cell features p-nc-Si:H and a tailored TCO with a sheet resistance of 40?? per sqaure, while the p-a-Si:H cell features p-a-Si:H and a TCO with a sheet resistance of 80?? per square. Due to the excellent s and eactivation energy Ea of p-nc-Si:H, the rear contact resistivity is reduced.
[00033] In another embodiment, the implementation of p-nc-Si:H 107 together with matched TCO leads to a dramatic reduction in the contact resistivity at the rear side, resulting in an efficiency increase to 26.30%. As this contact, the overall resistance depends mainly on the bulk resistance of p-nc-Si:H itself and on the contact resistivity at the p-nc-Si:H–TCO interface. Therefore, gaining the optimal p-nc-Si:H layer is of critical importance to achieve high-efficiency SHJ solar cells.
[00034] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
[00035] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprise” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.
, Claims:I/We claim:
1. A heterojunction solar cell device comprises:
A silicon material-based heterojunction solar cell (HSC), SHJ solar cells with improved back contacts consisting of p-type doped nanocrystalline silicon, a transparent conductive oxide (TCO) with a low sheet resistance, The hole selectivity and hole transport through the TCO–p-nc-Si:H layer, open circuit voltage VOC and fill factor (FF), activation energy Ea, p-nc-Si:H nanocrystals, high power conversion efficiency.
2. The system of claim 1, wherein a Silicon heterojunction (SHJ) solar cells have high power conversion efficiency owing to their effective passivating contact structures.
3. The system of claim 1, wherein a Silicon heterojunction (SHJ) solar cells have layers of p-nc-Si:H, i-a-Si:H, and n-nc-SiOx:H semiconductor materials with transparent conductive oxide layer (TCO).
4. The system of claim 1, wherein the efficiency of back junction SHJ solar cells have improved with back contacts consisting of p-type doped nanocrystalline silicon and a transparent conductive oxide with a low sheet resistance.
5. The system of claim 1, wherein a solar cells system is fabricated by the commercial SHJ research and development line on LONGi M2.
6. The system of claim 1, wherein the system contains the thickness of the i-a-Si:H layer is almost same (6?nm), while the p-nc-Si:H layer (21?nm) is much thicker than that of p-a-Si:H (about 5?nm).
7. The system of claim 1, wherein the activation energy of the proposed device is recorded as 350 MeV.
8. The system of claim 1, wherein the power conversion efficiencies recorded up to 26.81% and fill factors up to 86.59%.