Novel and Wide-Ranging Color Tuning Photoluminescent Properties of Zn2+/Sm3+ Co-Doped Tetragonal Scheelite-Type SrWO4 Nanophosphors: Energy Transfer and Realization of White Emission for w-LEDs Application

For the advancement of white light emitting diodes (WLEDs) exhibiting increased color tunability, novel photoluminescence color tunable phosphors through energy transfer (ET) are required. The existing work explains the structural and spectroscopic properties of -SrWO4:2Sm(3+) co-doped with x at.% -Zn2+ (x = 0, 0.5, 1, 2, 5, 7, 10 at.%) and it is also the first time that it has been synthesized using the polyol method. X-ray diffraction (XRD) and DSC/TGA were used to examine the crystalline structure, thermal stability, and morphology of synthesized nanophosphors. The emission intensity and energy transfer were observed via excitation and emission spectra. The XRD results confirmed that the synthesized samples exhibit the single phase tetragonal structure with space group I4(1/a). The PL findings show that the photoluminescence color tuning from bluish white to yellowish orange and eventually to deep orange was achieved by forming the Zn2+-> Sm3+ energy transfer (ET) in SrWO4 :Sm3+, Zn2+ phosphors. The ET mechanism of Zn2+-> Sm3+ is explained via Dexter's electric multipole interaction theory and Reisfeld's approximation theory, which indicates that the ET process is caused by the dipole-dipole interaction. In addition, the samples with an appropriate composition ratio of Zn2+/ Sm3+ exhibit excellent luminescence intensity and a wider color tuning range under different excitations, whose emission intensity exceeds 243 times the initial value. The warm-white light, having a softer correlated color temperature (CCT) of 4315 K with CIE coordinates of (0.39, 0.31), was produced by the 7 at.% -Zn2+ co-doped SrWO 4:2Sm(3+) nanophosphor. All the findings corroborate that SrWO4:Sm3+, Zn2+ nanophosphors can be served as the multicolor emitting phosphor materials to be used in WLEDs applications.

Automated summary

Phosphors with tunable photoluminescence color through energy transfer have been synthesized and can be used in WLEDs applications, exhibiting excellent luminescence intensity and a wider color tuning range.