MoO_<i>X</i>/Au/MoO_<i>X</i>‐Based Composite Heterocontacts for Crystalline Silicon Solar Cells Achieving 22.0% Efficiency

Designing an effective carrier‐transport layer is crucial for achieving highly crystalline silicon (c‐Si) solar cells. MoO X , with its high work function and wide bandgap, is the preferred choice for hole‐transport‐layer (HTL) materials in c‐Si solar cells. However, the limited reflection ability and conductivity of MoO X in the rear contact lead to a decrease in the short‐circuit current of the solar cells. In this study, an ultrathin Au interlayer is inserted between two MoO X layers to construct a MoO X /Au/MoO X (MAM) composite HTL. First, the composite HTL with a high work function (Au) contributes to upward band bending at the c‐Si surface to render excellent hole selectivity. Second, the MAM composite HTL effectively improves the backside reflectance of the devices at long wavelengths. Moreover, the insertion of Au introduces oxygen vacancies into the MAM composite HTL, resulting in a high conductivity of 7.592 × 10 −2 S m −1 . The conductivity of the MAM composite is an order of magnitude higher than that of single‐layer MoO X , which increases the short‐circuit current density of the corresponding device by 1.7 mA cm −2 . Consequently, the MAM‐based solar cells show a power conversion efficiency (PCE) of 22.0%, representing the highest PCE reported for MoO X ‐based p‐type c‐Si solar cells.