Efficiency Approaching 24% in MoO _x /Silicon Heterojunction Solar Cells Through Tailored Annealing Treatment

The development of high‐efficiency crystalline silicon ( c ‐Si) heterojunction solar cells is contingent on the engineering of efficient carrier transport layers. Molybdenum oxide (MoO _x ) emerges as a promising dopant‐free hole transport layer (HTL) material for c ‐Si solar cell fabrication, owing to its high work function and wide bandgap. However, dangling bonds on the silicon surface cause the reduction of the open‐circuit voltage ( V _oc ) and fill factor (FF) of the solar cell. MoO _x ‐based solar cells face issues such as oxygen vacancies and parasitic absorption. These problems hinder performance improvement by reducing the separation of photogenerated carriers, ultimately limiting the increase in power conversion efficiency (PCE). In this work, nitrogen–hydrogen annealing effectively reduces silicon surface dangling bond density, while optimized MoO _x thickness minimizes parasitic absorption. These modifications enhance solar cell performance, increasing open‐circuit voltage from 721.7 to 731.7 mV and improving fill factor from 74.58% to 80.01%. The results demonstrate the potential of MoO _x as an efficient HTL for high‐performance crystalline silicon solar cells. The cell achieves a remarkable PCE of 23.96%. This study explores the potential application of MoO _x as an HTL in n‐type c ‐Si solar cells and provides valuable insights for the design of high‐performance solar cells.