Chalcogenide Perovskite EuHfS₃ with Low Band Gap and Antiferromagnetic Properties for Photovoltaics

Chalcogenide perovskites represent a promising class of materials known for their robust stability, environmentally friendly composition, and intriguing optoelectronic characteristics. Their A-site cation is largely dependent on nonmagnetic Ca, Sr, Ba elements, showing little influences on the optoelectronic properties of chalcogenide perovskites. Here, by introducing magnetic element Eu as A-site cation, we present a comprehensive investigation into the crystal structures, band characteristics, optoelectronic features, and magnetic behaviors of EuHfS₃, targeting for photovoltaics. EuHfS₃ adopts a distorted perovskite structure within the Pnma space group. This structure allows for various magnetic configurations, setting foundations for multiple photovoltaic effect. The conduction band maximum primarily originates from the Hf 5d orbitals, akin to SrHfS₃. Intriguingly, the presence of Eu spin-up 4f orbitals lifts the covalence band minimum, consequently narrowing the band gap of EuHfS₃ (1.6 eV), which is suitable for absorber layer in p-i-n junction solar cells. Moreover, zero field cooled magnetization measurements reveal antiferromagnetic behavior in EuHfS₃, indicating further spin photovoltaic effect. The integration of magnetic properties into chalcogenide perovskites, in conjunction with their inherent semiconducting attributes, holds promise for future advancements in photovoltaics and other spintronic device technologies.