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

Ultra-thin MoO
_x
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, MoO
_x
electronic structure by oxygen dilution during the evaporation have influence to the MoO
_x
work function and hence reduce hole injection. XPS study confirmed the electronic structure and chemical composition of the evaporated and annealed (Ar and O
₂
atmosphere) MoO
_x
sample. TEM showed a clear interface contact between the ITO/MoO
_x
/a-SiH(i) layers and no diffusion between the layers after annealed at 140 °C. Fabricated 10 nm thick MoO
_x
/n-Si solar cells archived an efficiency of 20.04%, FF of 73.79 % and J
_sc
of 38.40 mA/cm
²
. A sever degradation in FF and J
_sc
was noticed by increasing the MoO
_x
thickness due to diffusion of layers and high parasitic absorption of MoO
_x
.