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

Abstract

An 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.

Low‐Cost Metallization Based on Ag/Cu Fingers for Exceeding 25% Efficiency in Industrial Silicon Heterojunction Solar Cells

“…Annealing treatments commonly facilitate the conductivity of the finger and the contact performance between the metal electrodes and ITO. Due to the narrow selectable range of annealing temperatures for SHJ solar cells, [37] we optimized the annealing time to obtain the best performance for the Ag/Cu fingers in Figure 5a. As the annealing time increases from 4 to 10 min, the volume resistance gradually decreases from 5.04 to 4.84 Ω cm accompanied by a drop in the magnitude of the decrease.…”