Small-area Si Photovoltaics for Low-Flux Infrared Energy Harvesting

Silicon photovoltaics are prospective candidates to power mm-scale implantable devices. These applications require excellent performance for small-area cells under low-flux illumination condition, which is not commonly achieved for silicon cells due to shunt leakage and recombination losses. Small area (1-10 mm²) silicon photovoltaic cells are studied in this work, where performance improvements are demonstrated using a surface n-type doped emitter and Si₃N₄ passivation. A power conversion efficiency of more than 17% is achieved for 660 nW/mm² illumination at 850 nm. The silicon cells demonstrate improved power conversion efficiency and reduced degradation under low illumination conditions in comparison to conventional crystalline silicon photovoltaic cells available commercially.