Introducing a supercritical fluid technique to reduce passivation layer interface defects in passivated emitter rear contact cells

Improving material and interface defects are an important issue in reducing solar cell leakage current and enhancing their efficiency. From back surface field (BSF)-based solar cell to passivated emitter and rear cell (PERC), solar cell structures have been designed to reduce defects. In this study, a supercritical fluid (SCF) technique is applied as a low temperature defect passivation technology to passivate defects in a PERC solar cell, enhancing device performance. Owing to the high penetration and high solubility of the supercritical fluid, hydrogen is the passivation source carried into the device to passivate Al2O3/Si interface defects. Furthermore, electronic analysis is used to confirm the benefits of the SCF treatment on the solar cell properties of open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), efficiency, power (Pmax) and series resistance (Rs), all measured under a standard light source. Finally, a model is proposed to explain how the SCF treatment passivates interface defects and enhances device performance.