V_oc transient in silicon heterojunction solar cells with µc-SiOx:H window layers

Silicon heterojunction (SHJ) solar cells with hydrogenated microcrystalline silicon oxide (µc-SiOx:H) emitters are fabricated and studied using the open circuit voltage (V _oc) transient. The built-in electric field (E _in), minority carrier lifetime, hole mobility, and a-Si:H/c-Si heterointerface valance band offset (ΔE _v) of the solar cells can be excavated by the V _oc transient. The rising rate of the V _oc transient curve, which has not been studied in previous research, is found to be dependent on E _in in SHJ cells. The measurements of the V _oc transient curves at different excitation intensities are used as a powerful approach for analysis of the ΔE _v difference between SHJ cells with different µc-SiOx:H emitters. Based on this analysis, it is demonstrated that the origin of the S-shaped J–V characteristics of SHJ cells lies in an inferior E _in and/or severe interface ΔE _v, and the role of ΔE _v is more dominant. (paper)