Improved V 2 O X Passivating Contact for p ‐Type Crystalline Silicon Solar Cells by Oxygen Vacancy Modulation with a SiO X Tunnel Layer

Transition metal oxide (TMO) thin films featuring tunable work function, high transmittance, and simple fabrication process are expected to serve as carrier-selective transport layers for high-efficiency crystalline silicon (c-Si) solar cells. TMOs are prone to reaction or elemental migration with adjacent materials, which leads to uncontrollable optical and electrical properties. In this work, V2OX passivating contact, a promising hole transport layer (HTL) thanks to its high work function, is investigated and implemented in p-type c-Si solar cells. An ultrathin SiOX tunnel layer is intentionally introduced by UV/O3 pretreatment to suppress the redox reaction at c-Si/V2OX interface. Both saturation current density and contact resistance are reduced with the presence of UV-SiOX due to the well tunned oxygen vacancies in SiOX and V2OX thin films. The power conversion efficiency (PCE) based on p-Si/UV-SiOX/V2OX/Ag rear contact achieves 21.01% with an increased open-circuit voltage of 635 mV and fill factor (FF) of 83.25%.