Colour tuning via crystalline site-selected energy transfer in a Sr2SiO4:Eu2+,Pr3+ phosphor

Spectral adjustment based on the energy transfer process between donor-acceptor pairs has been routinely used to design luminescent materials with different colours and absorption bandwidths. This work reports an alternative way to design new luminescent materials based on a site-selected energy transfer mechanism using high precision control of dopants. The new material Sr2SiO4: Eu2+, Pr3+ has been successfully synthesized to show versatile emissions under site-selected excitation. We demonstrate an efficient site-selected energy transfer process from Eu2+ to Pr3+ and that dual-mode spectral control can be achieved by choosing Eu2+ in Sr2SiO4 as a yellow emission centre and Pr3+ as a red and near infrared emission centre. Therefore a yellow-to-orange phosphor has been realized with excitation-dependent adjustable red and near infrared emissions. The site-selected spectral adjustments and energy transfer mechanism are investigated in detail. This work suggests the design and synthesis of new materials for application in solar cells and white LED devices."973'' program [2014CB643801]; National Natural Science Foundation of China [21271191, 20971130, 51272259, 51572232, 51561135015, 51602271]SCI(E)ARTICLE51022-1026