Silicon Heterojunction Solar Cells with MoO_x Hole-Selective Layer by Hot Wire Oxidation–Sublimation Deposition

In this article, a novel hot wire oxidation–sublimation deposition (HWOSD) technique, as an optional technology, is developed to prepare molybdenum oxide (MoO_x) thin films. Silicon heterojunction (SHJ) solar cells with the HWOSD MoO_x as a hole-selective transport layer (HSL) are fabricated. A power conversion efficiency up to 21.10% is achieved on a champion SHJ solar cell using a 14 nm MoO_x layer as the HSL. Dark current density–voltage–temperature (J–V–T) characteristics of the SHJ solar cell are measured at temperatures ranging from 200 to 380 K. Transport processes including thermionic emission of electrons over the potential barrier and quantum-assisted tunneling of holes through the gap states in the MoO_x layer are used to fit the J–V curves of the MoO_x/n-c-Si heterojunction. The investigation of the transport mechanisms provides a better understanding of the characteristics of the novel SHJ solar cells and it is helpful to fully demonstrate the potential of such kinds of solar cells in the future.