Wurtzite CuNi₂InS₄ Nanocrystals: A Quaternary Chalcogenide Magnetic Semiconductor

For the first time, quaternary chalcogenide CuNi₂InS₄ nanocrystals with a wurtzite structure have been designed and fabricated as a new magnetic semiconductor. The phase structure analysis suggests that the synthesized wurtzite CuNi₂InS₄ phase has a disordered structure in which Cu⁺, Ni²⁺, and In³⁺ ions share the same lattice site of the unit cell with a random cation distribution. The prepared CuNi₂InS₄ nanocrystals have uniform bullet-like morphology, small size distribution, good monodispersity, and high crystallinity. The magnetic properties investigation reveals that the wurtzite CuNi₂InS₄ nanocrystals can exhibit a weak ferromagnetic moment with the blocking temperature at around 13 K thanks to the disordered wurtzite structure and the high content of magnetic Ni²⁺ ions. As for the semiconducting properties, the as-obtained wurtzite CuNi₂InS₄ nanocrystals show a strong and broad visible light absorption and have a direct bandgap of 1.45 eV. Due to their favorable optical properties, the fabricated thin film of CuNi₂InS₄ nanocrystals exhibits a good photoelectric response to the solar spectrum, which makes the obtained new phase potential candidate for applications in the photovoltaics. This work demonstrates a new metastable I-II₂-III-VI₄ chalcogenide that can be used to render multiple functionalities and applications.