Tunable emission of Ce3+ in (K, Rb)3GdSi2O7 phosphors toward broadband cyan luminescence

In an effort to obtain a novel cyan-emitting phosphor, the [K 1-x Rb x ] 3 GdSi 2 O 7 : yCe 3+ materials (x = 0, 0.1, 0.2, 0.3, 0.4, y = 0, 0.005, 0.01, 0.02, 0.03, 0.04) are synthesized via a solid-state reaction pathway, and their crystal structure and luminescence behaviors are studied systematically. The chemical substitution of Rb + in the K + sites can enlarge the K 3 GdSi 2 O 7 host lattice and help to the blue-shifting of emission band of Ce 3+ ions due to the decreased crystal field splitting effect. It is also confirmed that the Ce 3+ ions tend to enter [Gd1O 6 ] and [Gd 2 O 6 ] polyhedrons simultaneously. Consequently, the [K 0.7 Rb 0.3 ] 3 GdSi 2 O 7 : Ce 3+ phosphor yields a broadband cyan emission centered at 492 nm with the full width at half maximum (FWHM) of ∼115 nm upon 365 nm excitation. The optimal concentration of Ce 3+ dopant is determined to be 0.01, and the concentration quenching effect can be attributed to the dipole−dipole interactions. The white light emitting diode (WLED) device fabricated by employing the discovered [K 0.7 Rb 0.3 ] 3 GdSi 2 O 7 : 0.01Ce 3+ phosphor displays a high color rendering index (R a = 91.7) and a low correlated color temperature (CCT = 3749 K). This work may promote the development of cyan phosphors for near ultraviolet-converted WLEDs with high performance.