Site‐Selective Occupancy of Eu2+Toward Blue‐Light‐Excited Red Emission in a Rb3YSi2O7:Eu Phosphor

Abstract Establishing an effective design principle in solid‐state materials for a blue‐light‐excited Eu2+‐doped red‐emitting oxide‐based phosphors remains one of the significant challenges for white light‐emitting diodes (WLEDs). Selective occupation of Eu2+in inorganic polyhedra with small coordination numbers results in broad‐band red emission as a result of enhanced crystal‐field splitting of 5d levels. Rb3YSi2O7:Eu exhibits a broad emission band atλmax=622 nm under 450 nm excitation, and structural analysis and DFT calculations support the concept that Eu2+ions preferably occupy RbO6and YO6polyhedra and show the characteristic red emission band of Eu2+. The excellent thermal quenching resistance, high color‐rendering index Ra(93), and low CCT (4013 K) of the WLEDs clearly demonstrate that site engineering of rare‐earth phosphors is an effective strategy to target tailored optical performance.