Highly Transparent Nanoscale Tunnel Oxide Polysilicon Passivated Contacts: Optimisation, Analysis, and Impact Study

The presented work on nanometre scale ultra‐thin tunnel oxide passivated contact (UT‐TOPCon) technology presents a promising pathway for enhancing power conversion efficiency in Si solar cells by mitigating parasitic optical losses. The in‐depth optimisation demonstrates record‐low surface recombination currents for a polysilicon layer under 3 nm thick, measuring 0.8 fAcm −2 on planar and 1.3 fAcm −2 on textured surfaces. Low specific contact resistivities between 2.5 and 5 mΩcm 2 were measured on various samples, confirming its excellent carrier transport properties. Furthermore, optical properties were characterised and the opto‐electrical inputs were incorporated into a comprehensive numerical simulation study to evaluate the impact of its application for Si‐perovskite tandem and various single‐junction Si cell architectures. The results indicate significant performance improvements to Si‐perovskite tandem devices, and very high efficiency potential of 26.7% in front and rear UT‐TOPCon designs and up to 27.5% in interdigitated back‐contact UT‐TOPCon structures.