Mechanical stress effects on crystalline-Si photovoltaic cells: Bandgap deformation and piezoresistive mobility enhancement

This study focuses on assessing the impact of mechanical stress on crystalline silicon (c-Si) photovoltaic (PV) cells in terms of band deformation and piezoresistance. Although piezoresistive mobility enhancement is beneficial for high-sensitivity stress sensing and improving transistor performance, its effect on c-Si solar cells remains unclear. Simulation models were developed using bifacial passivated emitter and rear cell and interdigitated back contact experiments to systematically evaluate both band deformation and piezoresistive effects. The results indicate that band deformation was highly sensitive to stress and caused negative changes in performance parameters, whereas piezoresistive mobility enhancement had a more pronounced adverse effect despite its weaker stress sensitivity. Band deformation reduced the open-circuit voltage, whereas piezoresistive mobility enhancement lowered the short-circuit current density. Stresses in the MPa range were found to have a significant impact, with performance degradation worsening as stress levels approached the sub-GPa range. In conclusion, maintaining stress-free device operations are essential to preserve optimal cell performance.