Solution-Processed Molybdenum Trioxide as Hole Selective Contact for Crystalline Silicon Solar Cells

High-efficiency silicon solar cells requires an effective carrier selective contact. Over the past few years, molybdenum trioxide (MoO3) has been widely used as the hole selective contact (HSC) for silicon heterojunction solar cells. The high work function and wide energy gap lead to favorable band bending for hole transport across the MoO3/Si interface. In previous studies, the MoO3 is commonly deposited by thermal evaporation. Here, we propose a simple solution-processed method to form a MoO3 HSC for conventional crystalline silicon (c-Si) solar cells. The crystalline MoO3 nanoparticle solution with a concentration of 2.3-2.7wt% was blade coated on the rear side of an n+/p silicon solar cell without an antireflective coating. By measuring the current-voltage (I-V), contact resistivity (ρc), and external quantum efficiency (EQE), we investigate the photoelectric properties of the solar cells incorporating the MoO3 nanoparticle layer. We show that the MoO3 HSC has a low contact resistivity of 29.5 mΩ cm between p-type Si and the silver electrode. The EQE exhibits enahcement on the near-infrared wavelength regime, indicating a field passivation effect. Overall, the n+/p c-Si solar cell incorporating the solution-processed MoO3 HSC exhibits an improved power conversion efficiency (PCE) of 11.8% due to an increased open-circuit voltage (Voc) and fill factor (FF).