Survey of material options and issues for thin film silicon solar cells

The high production cost of thick high-efficiency crystalline silicon solar cells inhibits widespread application of photovoltaic devices whereas the most developed of thin film cell technologies, that based on amorphous silicon, suffers inherent instability and low efficiency. Crystalline thin-film silicon solar cells offer the potential for a long-term solution for low cost but high-efficiency modules for most applications. This paper reviews the progress in thin-film silicon solar cell development over the last two decades, including progress in thin-film crystal growth, device fabrication, novel cell design, new material development, light trapping and both bulk and surface passivation. Quite promising results have been obtained for both large-grain (>100 μm) polycrystalline silicon material and the recently developed microcrystalline silicon materials. A novel multijunction solar cell design provides a new approach to achieving high-efficiency solar cells from very modest quality and hence low-cost material. Light trapping is essential for high performance from thin-film silicon solar cells. This can be realized by incorporating an appropriate texture on the substrate surface. Both bulk and surface passivation is also important to ensure that the photogenerated carriers can be collected effectively within the thin-film device.