Light Management for Efficient Crystalline Si Heterojunction Solar Cells

High efficiency crystalline Si heterojunction solar cells have been achieved with an independently-confirmed efficiency of 19.3% on a p-type silicon wafer. The hydrogenated amorphous silicon (a-Si:H) emitter and back contact were deposited using high-rate hot-wire chemical vapor deposition. This high efficiency cell has an open circuit voltage of 0.678 V, fill factor of 78.6%, and short circuit current density of 36.2 mA/cm². Improved surface texturing, surface cleaning, back contacts, indium tin oxide (ITO) thickness, and surface passivation all contribute to the high efficiency. The high open circuit voltage results from the good amorphous Si surface passivation with a minority carrier lifetime of ∼ 1 ms. Light management was applied to further improve the cell performance. ITO layer was optimized to maximize the current collection. This layer acts as a transparent contact layer to the emitter as well as a single anti-reflectance layer to minimize the optical loss due to reflection.