Charge compensator adjusts the luminescence intensity of ZnWO4: Sm3+ full spectrum phosphors: A bifunctional phosphors for plant growth lights and FIR thermometers

Full spectrum white LED plant growth light sources are suitable for use in conditions requiring a high color rendering index. In addition to red and blue light, green light was shown to have a positive impact on plant growth in earlier studies. In this work, a series of Sm3+ doped ZnWO4 phosphors was prepared using the high-temperature solid-state reaction method. Li+ serves as a charge compensator to reduce lattice defects caused by non-equivalent isomorphism. XRD measurements and Rietveld refinement were used to investigate the phase composition and structural properties of the samples. The luminescent properties of the samples were tested using a fluorescence spectrophotometer. The Li + introduction can significantly improve the energy transfer from the matrix to Sm3+ and the luminescence intensity of Sm3+. In addition, this phenomenon was explained with non-equivalent isomorphism and the charge density difference diagram. The LED lamp was prepared using ZnWO4: 0.004Sm3+, 0.004Li + phosphor and LED chip. The emitted full spectrum light can match well with the absorption spectrum of plant pigments. The color rendering index of the LED lamp is greater than 91. And the comparative experiment of plant cultivation shows that the prepared LED plant lamp has good effects. The dependence of luminescence properties of ZnWO4: 0.004Sm3+, 0.004Li+ phosphor on temperature was determined. Based on fluorescence intensity ratio (FIR) technology, the maximum SaMAX and SrMAX are 52 % K−1 at 453 K and 9.31 % K−1 at 303 K, respectively. As the temperature increases, the chromaticity shift (Δs) value is 0.254. The benefits of the ZnWO4: 0.004Sm3+, 0.004Li+ phosphor are the straightforward synthesis process, low cost, pure phase, full spectrum, high color rendering index, tunable red-to-blue ratio, and temperature monitoring function. Therefore, this phosphor is an ideal material in plant growth and optical temperature measurement.