Low Oxygen Content MoOx and SiOx Tunnel Layer Based Heterocontacts for Efficient and Stable Crystalline Silicon Solar Cells Approaching 22% Efficiency

Abstract

AbstractIn crystalline silicon (c‐Si) solar cells, the hole transport layer (HTL) made of high oxygen content MoOx (x > 2.85, H‐MoOx) evaporating from molybdenum trioxide is not ideal due to low optical bandgap and interface reaction effects. This limits the power conversion efficiency (PCE) and stability of c‐Si solar cells. To improve this, low oxygen content MoOx (x < 2.85, L‐MoOx) with a wide bandgap of 3.87 eV, deposited using molybdenum dioxide (MoO2), is explored and implemented. The c‐Si/SiOx (FGA, forming gas annealing)/L‐MoOx heterojunction has a low contact resistivity of ≈15.06 mΩ cm2, which is almost one order of magnitude lower than that of c‐Si/SiOx(FGA)/H‐MoOx heterojunction. Using L‐MoOx as the HTL, a c‐Si solar cell based on the SiOx passivation layer shows a fill factor of 84.38% and PCE of 21.75%, representing the highest efficiency for MoOx‐based p‐type c‐Si solar cells. Scanning transmission electron microscopy results show that the L‐MoOx HTL effectively enhances the stability of c‐Si solar cells when exposed to air by reducing Ag and Si element diffusion into MoOx. This successful preparation of efficient and stable MoOx HTL films, while preserving their field‐effect passivation ability, provides valuable insights into the development of high‐performance HTL.