Investigation of Light-Induced Degradation in B-Doped Mono-Like Silicon PERC Cells by a Cycling Test With Light Soaking and Dark Annealing

We investigated light-induced degradation (LID) of passivated emitter and rear contact cells fabricated from B-doped cast-grown mono-like Si by conducting a cycling test comprising light soaking (illumination intensity of 1 sun at 95 °C) and dark annealing (at 175 °C for 30 min). Degradation and regeneration were observed in both the first light soaking (LS1) and subsequent light soaking after dark annealing (LS2 and LS3), but the extent and timescale were significantly different. The normalized defect density (NDD) during light soaking was analyzed by fitting based on first-order consecutive reaction models. Systematic residuals between the NDD and the three-state consecutive reaction model were observed in the early and regeneration regions during LS1. We discussed the scenarios that could explain the cause of these residuals, and the values of the reaction rate constants and capture cross-section ratio suggested that two types of LIDs occurred simultaneously in LS1. We concluded that one of the two types of LIDs was light- and elevated-temperature-induced degradation, but we could not identify the other LID with a larger extent and timescale.