p-type heterojunction bifacial solar cell with rear side carrier selective contact

Molybdenum oxide (MoO_x), owing to its large work function, is an attractive material for hole-selective contact (HSC) in crystalline Si-based solar cells because it introduces upward band bending when constructed into a heterojunction silicon (SHJ) cell structure. In this study, we fabricated a p-type SHJ bifacial solar cell with a rear-side MoO_x HSC layer. The MoO_x thickness was varied from 3 to 15 nm, and cell bifaciality was addressed. The cell efficiency decreased when the MoOx thickness was increased to more than 5 nm. A maximum front-side cell efficiency of 17.89% was obtained, while the rear efficiency was 16.02%, which shows the potential of MoO_x for p-type bifacial cell fabrication. The maximum open circuit voltage (V_OC) and short circuit current density (J_SC) for the front side were 635.71 mV and 35.57 mA/cm², respectively, while the rear side V_OC and J_SC were 623.62 mV and 32.67 mA/cm², respectively. The interfacial properties were carefully studied as a function of MoO_x thickness. This work demonstrates the importance of selecting MoO_x for p-type crystalline silicon (c-Si) solar cells.