CsRb(PSe4)2

CsRb(PSe4)2 is a mixed-cation phosphoselenide semiconductor compound combining cesium and rubidium with phosphorus and selenium in a 1:1:2 stoichiometric ratio. This material belongs to the family of metal phosphoselenides, which are primarily investigated for nonlinear optical applications, particularly second-harmonic generation and mid-infrared photonics, where they offer potential advantages over conventional oxide and sulfide alternatives due to their tunable bandgap and enhanced optical transparency windows. The material remains largely in the research phase; it exemplifies an emerging class of quaternary chalcogenide semiconductors being developed for photonic devices where conventional materials exhibit insufficient performance in specific wavelength regions.