Kinetics of light and elevated temperature-induced degradation in cast mono p-type silicon

Abstract

Cast mono Silicon (Si) technology has the advantages of low cost, i.e., multicrystalline silicon (mc-Si), and high efficiency, i.e., Czoch-ralski-grown silicon (Cz-Si). Cast mono Si has a similar performance to current Cz-Si counterparts with a solar cell structure, i.e., a passivated emitter and rear cell (PERC). However, the severity of light and elevated temperature-induced degradation (LeTID) on cast mono Si solar cells may be similar to mc-Si, not Cz-Si. To clarify the LeTID kinetics in the p-type cast mono silicon, we observed the effect that LeTID had on the carrier lifetime. First, a series of carrier lifetime measurements were performed to investigate LeTID kinetics in the accelerated regeneration process via high intensity illumination at elevated temperatures and modulating kinetics via dark annealing before illumination. Next, we documented the evolution of a carrier lifetime to investigate the stability of regenerated state at 75 °C and light intensity of ~ 1 kW/m2. The results show that the effect of dark annealing on LeTID kinetic modulation could be explained by the B-H defect precursor concentration and defect reservoir theory, which originate from the results for mc-Si. An accelerated regeneration method that combines dark annealing and illumination, with high intensity at an elevated temperature, can yield a higher value and improved LeTID stability in terms of the lifetime, as compared with illumination without pre-annealing. This implies that this mixed process may be a potential method to provide both improved performance and high anti-LeTID properties in Si PERC solar cells.