Achieving 23.83% conversion efficiency in silicon heterojunction solar cell with ultra‐thin MoO_x hole collector layer via tailoring (<i>i</i>)a‐Si:H/MoO_x interface

Abstract

Abstract Thin films of transition metal oxides such as molybdenum oxide (MoO x ) are attractive for application in silicon heterojunction solar cells for their potential to yield large short‐circuit current density. However, full control of electrical properties of thin MoO x layers must be mastered to obtain an efficient hole collector. Here, we show that the key to control the MoO x layer quality is the interface between the MoO x and the hydrogenated intrinsic amorphous silicon passivation layer underneath. By means of ab initio modelling, we demonstrate a dipole at such interface and study its minimization in terms of work function variation to enable high performance hole transport. We apply this knowledge to experimentally tailor the oxygen content in MoO x by plasma treatments (PTs). PTs act as a barrier to oxygen diffusion/reaction and result in optimal electrical properties of the MoO x hole collector. With this approach, we can thin down the MoO x thickness to 1.7 nm and demonstrate short‐circuit current density well above 40 mA/cm 2 and a champion device exhibiting 23.83% conversion efficiency.