Investigation of Problems in Crystalline Silicon Heterojunction Solar Cells by HAXPES

Abstract

We investigate the factors that degrade the conversion efficiency in the crystalline silicon heterojunction (SHJ) solar cell using hard X-ray photoelectron spectroscopy (HAXPES) and the potential of new materials for the carrier selective contact (CSC). Regarding the emerging transparent conductive oxide film (TCO) used in the SHJ solar cell, the hydrogenated indium oxide (IO:H) with high carrier mobility forms an oxide layer at the IO:H/substrate interface revealed by the evaluation of chemical bonding states by HAXPES, resulting in increasing the contact resistance. Moreover, the IO:H is reduced from the catalyst in the silver electrode paste, and silver oxide tends to form at the electrode/IO:H interface. In addition, the role of MoS₂, a two-dimensional layered material, as a CSC layer was investigated, found that and MoS₂ layer works as an electron selective layer for n-type Si substrate using angle-resolved HAPXES band bending evaluation.