Realization of “Region Solar Cell” With 70% Theoretical Energy Conversion Efficiency

Considerable progress has been achieved in semiconductor technologies. The development of epitaxially grown, highly doped Si:P (HDSiP) for low‐voltage power metal–oxide–semiconductor field‐effect transistors has provided further clarity on the mechanism of phosphorus behavior during annealing. Furthermore, sub‐10‐nm half‐pitch critical dimension has been realized via extreme‐ultraviolet (EUV) lithography or nanoimprint lithography (NIL). In June 2024, “Region solar cell” was proposed as a potential candidate for next‐generation photovoltaics. Its theoretical energy conversion efficiency can exceed 70% owing to photon absorption and countermeasures for a detailed balance. In a 2024 paper, it was claimed that Regions could be formed using ion implantation. Although the use of ion implantation technology was novel and original, it posed significant engineering challenges. In this study, we discuss new methods for fabricating a Region solar cell using the latest or already realized technologies, namely EUV lithography and NIL, and new insights into solar cell annealing from the development of HDSiP.