button cell battery cr2025.Two technologies to improve silicon solar cell efficiency

　　Two technologies to improve the efficiency of silicon solar cells provided to you by electronics enthusiasts. Recently, researchers have made breakthrough technological progress in seeking to improve the efficiency of solar cells. Among them are dry texturing to optimize the structure of the upper surface and inserting an intermediate porous silicon mirror at the epitaxial layer/substrate interface. Use these two methods

　　Recently, researchers have made groundbreaking technological advances in their quest to improve solar cell efficiency. Among them are dry texturing to optimize the structure of the upper surface and inserting an intermediate porous silicon mirror at the epitaxial layer/substrate interface. Using these two methods can increase the efficiency of solar cells to about 14%.

　　Two technologies to improve efficiency

　　Epitaxial thin-film solar cells are relatively cheap compared to bulk silicon-based solar cells. But the main drawback of current epitaxial thin-film solar cells is their relatively low efficiency. Two technologies have been shown to improve the efficiency of thin-film solar cells. One is to use halogen atom plasma processing to optimize the upper surface structure. The other technology is to introduce an intermediate reflector at the epitaxial layer/substrate interface. The optimized upper surface structure has the two advantages of meeting the requirements of uniform light scattering (Lambertian refraction) and reducing reflection by removing a small amount of silicon (because the epitaxial silicon layer is already quite thin). The introduction of intermediate mirrors (multiple Bragg mirrors) extends the path length of low-energy photons by at least 7 times, ultimately greatly improving the efficiency of solar cells.

　　low cost solar cells

　　Silicon solar cells based on monocrystalline or polycrystalline silicon substrates are the mainstay of the photovoltaic market. However, if all are made of high-purity silicon, the production of such solar cells is very energy-consuming and relatively expensive. To further promote the development of the photovoltaic industry, the production cost of solar cells should be greatly reduced by reducing material costs. Epitaxial thin-film silicon solar cells have the potential to become a low-cost alternative to bulk silicon solar cells. This screen-printed solar cell uses a cheaper substrate and a thinner active silicon layer (20μm) compared to current bulk silicon solar cells (200μm). This low-cost substrate consists of highly doped crystalline silicon wafers (pure silicon processed from metallurgical grade silicon or scrap). A thin layer of epitaxial active silicon is deposited on this substrate using chemical vapor deposition (CVD).

　　Plasma suede upper surface

　　By treating the upper surface of the active layer of a solar cell, surface light scattering changes, thereby affecting the performance of the solar cell. The purpose is to form the most ideal upper surface, 100% diffuse reflection (Lambertian refraction, showing total scattering). At this time, photons pass through the active layer at an average angle of 60°, which doubles the propagation path length. That is, an active layer that is only 20 μm thick appears optically to be 40 μm thick.

　　Industrial competitiveness

　　The production process of epitaxial thin-film silicon solar cells is very similar to that of traditional bulk silicon solar cells. Therefore, compared with other thin-film technologies, it is relatively easy to implement epitaxial thin-film silicon solar production in existing production lines. However, the main disadvantage of epitaxial thin film silicon solar cell industry competitiveness is that thin film silicon solar cells are less efficient than traditional bulk silicon solar cells: the open circuit voltage and fill factor of these cells can reach the same level as bulk silicon solar cells. A similar level, but due to the presence of an optically active thin layer (the active layer thickness of thin film silicon is only 20μm compared to the 200μm thickness of bulk silicon), when light is transmitted from the epitaxial layer to the substrate, the poor quality of the substrate causes light loss and short circuit Current loss can be up to 7mA/cm2. The challenge is to achieve the perfect balance between efficiency and cost, taking into account large-scale industrial production. This article describes two technologies that can extend the optical path length and therefore improve the efficiency of epitaxial thin film silicon solar cells: plasmonic texturing and the insertion of porous silicon mirrors at the interface of the low-cost silicon substrate and the active layer. The results show that these measures can increase the efficiency of epitaxial thin-film silicon solar cells to about 14%.

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