Multi-Junction Silicon Solar Cells

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This project aims to produce the first silicon-based solar cell with more than 30% efficiency, challenging the UNSW-held world record for conventional silicon wafer technology. Silicon-based solar cells are highly cost effective but have reached their efficiency limit (the amount of energy they can convert from sunlight).Tandem solar cells can generate more energy because they are able to collect solar energy from different wavelengths in sunlight but they are expensive to produce.A successful combination of the two technologies could produce a low-cost, highly efficient solar cell.Project innovationResearchers will take advantage of the affordability of silicon-based products by using silicon as the core component, and introduce other elements to form a multi-junction tandem stack. The stacked layers of different materials in this technology allow the solar cell to collect energy from more than one wavelength in sunlight.A material similar to silicon called germanium will be used to overcome some of the scientific challenges that arise when stacking cells on silicon in this way.Researchers at UNSW have already demonstrated a simple low-cost way of forming a layer of germanium on top of a silicon wafer. This virtual germanium wafer is much less expensive than a standard germanium wafer, but can be used for the deposition of a highly-efficient multiple-junction stack using standard technology.As part of the project, researchers will fabricate the first silicon-based solar cell with above 30% efficiency and then explore options for new equipment that can produce the multi-junction cells at a rate that matches the current rate of silicon-based solar cell production.This project brings together two world-leading research groups: the US National Renewable Energy Laboratory (specialists in multi-junction technology) and the University of NSW (leaders in silicon technology).They are well placed to explore a combination of the two technologies to produce the next generation of silicon-based solar cells.BenefitThis innovative approach will ensure Australian maintains its position as a leader in silicon cell technology development and pioneer a path for more efficient and affordable systems.

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