Precise Sn-Doping Modulation for Optimizing CdWO₄ Nanorod Photoluminescence

The cadmium tungstate rods have been given much attention due to their potential for usage in numerous luminescent applications. We have prepared single crystalline Sn-doped Cd_1-xSn_xWO₄ (where x = 0, 1, 3, and 5%) nanorods (NRDs) and characterized them using refined X-ray diffraction and TEM analysis, revealing a monoclinic phase and a crystallite size that decreased from 62 to 38 nm as Sn concentration increased. Precise Sn doping modulation in CdWO₄ NRDs causes surface recombination of electrons and holes, which causes the PL intensity to decrease as the Sn content rises. The chromaticity diagram shows that an increase in the Sn content caused a change in the emission color from sky blue to light green, which was attributed to the increased defect density. The photoluminescence time decay curve of all samples fit well with double-order exponential decay, and the average decay lifetime was found to be 1.11, 0.93, and 1.16 ns for Cd_1-xSn_xWO₄, x = 0, 1, and 5%, respectively. This work provides an understanding of the behavior of Sn-doped CdWO₄ NRDs during electron transitions and the physical nature of emission that could be used in bio-imaging, light sources, displays, and other applications.