Enhancing the Selectivity and Transparency of the Electron Contact in Silicon Heterojunction Solar Cells by Phosphorus Catalytic Doping

Abstract

AbstractAn intrinsic hydrogenated amorphous silicon (a‐Si:H(i)) film and a doped silicon film are usually combined in the heterojunction contacts of silicon heterojunction (SHJ) solar cells. In this work, a post‐doping process called catalytic doping (Cat‐doping) on a‐Si:H(i) is performed on the electron selective side of SHJ solar cells, which enables a device architecture that eliminates the additional deposition of the doped silicon layer. Thus, a single phosphorus Cat‐doping layer combines the functions of two other layers by enabling excellent interface passivation and high carrier selectivity. The overall thinner layer on the window side results in higher spectral response at short wavelengths, leading to an improved short‐circuit current density of 40.31 mA cm−2 and an efficiency of 23.65% (certified). The cell efficiency is currently limited by sputter damage from the subsequent transparent conductive oxide fabrication and low carrier activation in the a‐Si:H(i) with Cat‐doping. Numerical device simulations show that the a‐Si:H(i) with Cat‐doping can provide sufficient field effect passivation even at lower active carrier concentrations compared to the as‐deposited doped layer, due to the lower defect density.