Advancements in Passivation and Metallization Techniques for n-Type Monocrystalline Silicon Solar Cells

Crystalline n-type silicon (n-Si) solar cells are emerging as promising candidates to overcome the efficiency limitations of current p-type technologies, such as PERC cells. This article explores recent advances in passivation and metallisation techniques for monocrystalline n-Si solar cells, focusing on their impact on improving conversion efficiency and reducing manufacturing costs. The paper begins with a discussion of the importance of base material quality for n-Si cells. The impact of metallic impurities, oxide precipitates and thermal donors on minority carrier lifetime is analysed, as well as n-type silicon purification and passivation strategies, such as gettering. Next, the paper explores different contact passivation technologies, including silicon heterojunctions (SHJs), poly-Si and tunnel oxide TOPCon/POLO contacts, and metal oxide and organic compound contacts. The performance, advantages and manufacturing challenges of each technology are compared and discussed. Metallization techniques such as silver screen printing and more cost-effective and sustainable alternatives such as screen printing and copper plating are also examined. The impact of plating technologies on the performance of bifacial cells is also discussed. The paper then looks at n-Si bifacial solar cells and their potential to increase the energy efficiency of PV systems. Different bifacial cell concepts and their performance under real-world conditions are discussed, as well as the challenges and opportunities for their future development. Silicon-based tandem and multifunction solar cells are presented as a promising way to overcome the efficiency limits of single-junction cells. Perovskite-silicon tandems and III-V/silicon tandems, with their respective advantages and challenges, are examined in detail. Finally, the article discusses the economic and environmental aspects of n-type PV technologies, including cost of ownership (COO), discounted cost of energy (LCOE) and life cycle assessment (LCA). The importance of improving efficiency and reducing material use for the economic viability and sustainability of n-Si solar cells is highlighted. In conclusion, the paper highlights the crucial role of n-Si solar cells for the energy transition and highlights the opportunities and challenges for their development and large-scale deployment in the future.