Achievement of full-visible-spectrum lighting in Bi3+-activated strontium gallates via lattice site occupancy engineering toward WLEDs applications

Achieving full-visible-spectrum lighting in a single component is highly desired but still challenging for high-quality phosphor-converted white light emitting diodes (pc-WLEDs). Herein, a broadband emission of Sr3Ga4O9: Bi3+, Yb3+ phosphor covering full-visible-spectrum from 400 to 800 nm is explored via the lattice site occupancy engineering strategy. The Bi3+ singly doped Sr3Ga4O9 phosphor exhibits warm yellow emission for the 3P1→1S0 transition of Bi3+ at Sr1 and Sr3 sites. While the introduction of Yb3+ contributes to the emerge of an extra blue emission band at 445 nm accompanied with a significant enhancement of the integral photoluminescence intensity. It is demonstrated that the chemical substitution of Yb3+ into Sr sites induces the lattice disorder and the increased concentration of Sr vacancies, and the local chemical environment change dominates the occupation of Bi3+ into Sr2 sites, resulting in the remarkable blue emission. Moreover, the WLED device as-fabricated by combining the broadband cyan-emitting Sr3Ga4O9: Bi3+, Yb3+ and the red-emitting CaAlSiN3: Eu2+ phosphors exhibits a high color-rendering index (CRI) of 89.6 and a correlated color temperature (CCT) of 5382 K. This work provides a feasible strategy for regulating the Bi3+occupation in Sr3Ga4O9 matrix and boosts the photoluminescence performance of the corresponding phosphor with broadband emission covering the full visible spectrum.