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

摘要

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 at lambda(max)=622 nm under 450 nm excitation, and structural analysis and DFT calculations support the concept that Eu2+ ions preferably occupy RbO6 and YO6 polyhedra and show the characteristic red emission band of Eu2+. The excellent thermal quenching resistance, high color-rendering index R-a (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.