Influence of molybdenum oxide thickness, electronic structure, and work function on the performance of hole selective silicon heterojunction solar cells

Ultra-thin MoOx is capable of exhibiting high work function (< 6 eV), large band gaps (< 3 eV) are benefiting for surface passivation and hole selectivity layer in silicon solar cells instead of the doped layers due to high parasitic absorption. Importantly, MoOx electronic structure by oxygen dilution during the evaporation have influence to the MoOx work function and hence reduce hole injection. XPS study confirmed the electronic structure and chemical composition of the evaporated and annealed (Ar and O2 atmosphere) MoOx sample. TEM showed a clear interface contact between the ITO/MoOx/a-SiH(i) layers and no diffusion between the layers after annealed at 140 °C. Fabricated 10 nm thick MoOx/n-Si solar cells archived an efficiency of 20.04%, FF of 73.79 % and Jsc of 38.40 mA/cm². A sever degradation in FF and Jsc was noticed by increasing the MoOx thickness due to diffusion of layers and high parasitic absorption of MoOx.