Past, Present, and Future Outlook for Edge Isolation Processes in Highly Efficient Silicon Solar Cell Manufacturing

Abstract

This work highlights present research and mass production results of wet‐chemical solutions for industrial edge isolation of silicon solar cells, aiming for a reduction of nitric acid consumption and production costs as well as a simultaneous increase in efficiency. All processes are applied to either industrially passivated emitter and rear contact (PERC) or tunnel oxide‐passivated contact (TOPCon) solar cells. Herein, a review of different edge isolation techniques in the history of silicon solar cell processing is presented. Subsequently, novel wet‐chemical approaches are focused on, namely 1) HNO3‐reduced edge isolation (InOxSide Fusion), 2) HNO3‐free edge isolation (InOxSide Blue), and 3) batch cluster solution—a combination of an acidic inline and an alkaline batch tool for emitter edge isolation of PERC and TOPCon solar cells. For each of the approaches, cell results and total cost of ownership estimations are presented. Based on all findings, a comprehensive discussion between inline versus batch‐cluster processing is presented. All investigations are performed on industrial equipment, wafer sizes, and a solar cell efficiency level of above 23%.

Wet chemical poly-Si(n) wrap-around removal for TOPCon solar cells

“…In this article we focus on wet chemical removal of the parasitical poly-Si in hot diluted potassium hydroxide (KOH) because it is highly relevant for industrial TOPCon cells for reasons of cost efficiency and availability of chemicals in existing production lines. Single side wet chemical etching using KOH has been established successfully to remove the parasitic boron emitter (chemical etch isolation, CEI) on the rear side of TOPCon solar cells [10]. This knowledge can be transferred to poly-Si removal.…”

Stable Passivation of Cut Edges in Encapsulated N-Type Silicon Solar Cells Using Nafion Polymer

“…The traditional industrial solution for edge treatment focuses primarily on isolation of the edge [8]. Edge passivation is mainly achieved as a beneficial side effect of the surface passivation process of a solar cell and there is no cost-effective industrial solution for passivating just the cut edges of half, triple or shingled cells.…”