Insights into the Heat-Assisted Intensive Light-Soaking Effect on Silicon Heterojunction Solar Cells

Abstract

Heat-assisted intensive light soaking has been proposed as an effective posttreatment to further enhance the performance of silicon heterojunction (SHJ) solar cells. In the current study, it is aimed to distinguish the effects of heat and illumination on different (doped and undoped) layers of the SHJ contact stack. It is discovered that both elevated temperature and illumination are necessary to significantly reduce interface recombination when working effectively together. The synergistic effect on passivation displays a thermal activation energy of approximately 0.5 eV. This is likely due to the photogenerated electron/hole pairs in the c–Si wafer, where nearly all of the incident light is absorbed. By distinguishing between the effects of light and heat effects on the conductivity of p- and n-type doped hydrogenated amorphous silicon (a–Si:H) layers, it is demonstrated that only heat is accountable for the observed rise in conductivity. According to numerical device simulations, the significant contribution to the open-circuit voltage enhancement arises from the reduced density of defect states at the c–Si/intrinsic a–Si:H interface. In addition, the evolution of the fill factor is highly dependent on changes in interface defect density and the band tail state density of p-type a–Si:H.