Enhanced thermostability of Eu3+ ions photoluminescence by multi-level electron traps with various temperature responses

Abstract

Red-emitting phosphor is the main component material of white light-emitting diodes (WLEDs), enhancing its thermostability is a key challenge to improve the lighting quality. In this work, a strategy of constructing multi-level electron traps to compensate for fluorescence thermal quenching is proposed, and the Eu3+-doped phosphor host was modified by polycrystalline crystals. Owing to the asymmetry of coordination cation configuration in the host, atomic dislocations occur in the local spatial region resulting in an increase in cationic disorder, thus forming multi-level electron traps. The multi-level electron traps release electrons at different temperatures to compensate for the thermal quenching of Eu3+ luminescence, which results in a reciprocating change in the Eu3+ PL intensity. At 523 K, the relative emission intensity of Eu3+ dominant peak reaches 0.75 (λex = 394 nm peak:610–619 nm), and the maximum relative emission intensity reaches 0.99 (λex = 465 nm peak:700–714 nm), which indicates that the phosphor has excellent thermostability. These results manifest that the multi-level electron traps formed by modifying the activator host with polycrystalline crystals can greatly improve the thermostability of phosphors, which provides a new route for preparing phosphors with excellent thermostability.