Charge fluctuations at the Si-Si02 interface and its effect on surface recombination in solar cells

schematic energy diagram of charge in the semiconductor near surface and interface states as a product of dielectric and gate charge

Dr Sebastian Bonilla, Isabel Al-Dhahir, Mingzhe Yu and Phillip Hamer worked with Trina Solar to investigate the effect of applying optimally charged dielectric coatings to the front and rear surfaces of PERC cells.

Published in Solar Energy Materials and Solar Cells, the investigation involved modifying established models to accurately reflect fluctuations in external charge, allowing a precise representation of surface recombination velocity, with self-consistent parameters.

By correctly accounting for these parameters, insights into the passivation mechanisms are gained, which can aid the development of future devices. The researchers found the effect of charge fluctuation at the Si-SiO₂interface was significant for the depletion regime to the weak inversion regime, and that the efficiency of future PERC cells can improve up to 1% absolute when optimally charged dielectric coatings are applied to both the front and rear surfaces.