UV-Engineered Oxygen Vacancies in MoOX Interlayers Enable 24.15% Efficiency for Crystalline Silicon Solar Cells.

Molybdenum oxide (MoOX) has been widely utilized as a hole transport layer (HTL) in crystalline silicon (c-Si) solar cells, owing to characteristics such as a wide bandgap and high work function. However, the relatively low conductivity of MoOX films and their poor contact performance at the MoOX-based hole-selective contact severely degrade device performance, particularly because they limit the fill factor (FF). Oxygen vacancies are of paramount importance in governing the conductivity of MoOX films. In this work, MoOX films were modified through ultraviolet irradiation (UV-MoOX), resulting in MoOX films with tunable oxygen vacancies. Compared to untreated MoOX films, UV-MoOX films contain a higher density of oxygen vacancies, leading to an enhancement in conductivity (2.124 × 10-3 S/m). In addition, the UV-MoOX rear contact exhibits excellent contact performance, with a contact resistance of 20.61 mΩ·cm2, which is significantly lower than that of the untreated device. Consequently, the application of UV-MoOX enables outstanding hole selectivity. The power conversion efficiency (PCE) of the solar cell with an n-Si/i-a-Si:H/UV-MoOX/Ag rear contact reaches 24.15%, with an excellent FF of 84.82%.