Electron‐Selective ‍Lithium Contacts for Crystalline Silicon Solar Cells

Abstract Separating photogenerated charge carriers by carrier‐selective heterostructure contacts rather than by doped homojunctions is a promising pathway to approach the theoretical power conversion efficiency (PCE) limit of crystalline silicon (c‐Si) solar cells. An electron‐selective, hole‐blocking lithium contact for c‐Si solar cells is presented by simple thermal evaporation of air‐stable Li₃N powder. It is found that this lithium contact introduces only a minimal Schottky‐barrier height for electron transport at its interface with lightly doped n‐type c‐Si surfaces, resulting in a low contact resistivity of 12.8 mΩ cm². By implementing a full‐area electron‐selective lithium contact, an n‐type c‐Si solar cell with a PCE of 19% is achieved, representing a 4% absolute PCE improvement over reference devices with an aluminum contact. The choices of electron‐selective contact materials for photovoltaic devices, using simple, scalable fabrication methods are extended.