Solid-State Displacement Synthesis of Alkaline-Earth Selenide for White Emission through Alternating Current Electroluminescence

Alkaline-earth selenides (AESe) are functional materials of both fundamental and technological importance, but their chemical synthesis has met with limited success. Herein, a solid-state displacement reaction is described for the rapid synthesis of various AESe crystals without the need for hazardous chemicals. The reaction mechanism is studied by careful control of the experimental variables such as the reaction temperature (800-1400 °C), atmospheres (air, N₂, and N₂/H₂ mixture), and Se precursors (ZnSe and Se). Using AECO₃ and ZnSe (ZnS) as precursor materials under N₂/H₂ mixture atmosphere, we synthesized a series of AESe, AES, and AE(S,Se) crystals with high crystallinities. Doping of luminescent lanthanide ions such as Eu²⁺ is concomitantly achieved during the synthesis, yielding tunable photoluminescence that is useful for constructing white light-emitting devices in combination with electroluminescent ZnS:Cu.