Industrial‐Scale Preparation of Nanocrystalline n‐Type Silicon Oxide Front Contacts Using N₂O as an Oxygen Source for High‐Efficiency Silicon Heterojunction Solar Cells

Abstract

The advantage of employing an n‐type hydrogenated nanocrystalline silicon oxide (nc‐SiOx:H) layer as the front surface field (FSF) in silicon heterojunction (SHJ) solar cells is due to its low optical absorption coefficient and tunable refractive index. However, carbon dioxide (CO2) gas, one of the major precursor gases in the nc‐SiOx:H layer, deteriorates the crystallinity, which is one of the key factors affecting cell performance. Here, we successfully deposited a nc‐SiOx:H FSF layer with high crystallinity for SHJ solar cells by using nitrous oxide (N2O) as an alternative oxygen source instead of existing CO2. Compared with the use of CO2, the use of N2O as an oxygen source can achieve a 10% ~ 15% increase in the deposition rate of the nc‐SiOx:H layer, which can shorten the total processing tact‐time, thus having the potential to reduce production costs in large‐scale industrial applications. The influence of N2O as an oxygen source on the film properties was also investigated. By optimizing the proportion of N2O in the precursor gases, we finally fabricated 274.5 cm2‐area SHJ solar cells with an in‐house average efficiency of 25.76%, which is approximately 0.1%abs higher than that of their reference counterparts (using CO2 as an oxygen source), and obtained a certified efficiency of 25.79% for the champion cell independently confirmed by the ISFH CalTeC in Germany.