Thermally stable rare-earth-free double perovskite phosphors toward dual-mode optical thermometry and dual-functional lighting sources

Abstract

Novel Mn⁴⁺-activated Sr₂LuSbO₆ (SLSO) samples have a broad excitation wavelength and further emit a deep-red emission corresponding to the ²E_g → ⁴A_2g transition, which aligns well with the absorption of plant phytochromes. Additionally, the photoluminescence quantum yield of the optimal SLSO: 0.3%Mn⁴⁺ phosphor was measured to be 29.05%. Furthermore, the prepared sample also showcased an outstanding thermal stability and the emission intensity at 428 K maintained about 78.5% of that at 308 K. As a result, the corresponding red-LED device showed potential for application in plant growth lighting; meanwhile, the white-LED device with a beneficial luminescence efficiency (LE = 122 lm W⁻¹) exhibited good CRI and CCT values, which can be promising for indoor illumination. Apart from the lighting sources, the relative sensitivity of the luminescence intensity ratio (LIR) thermometer was found to be 2.893% K⁻¹@63 K by analyzing the different temperature responses of the vibrational sidebands (Stokes and anti-Stokes sidebands); finally, wide-range luminescence lifetime thermometry was introduced as well. This work suggests that the deep-red-emitting SLSO:Mn⁴⁺ phosphors with remarkable optical performances could be proposed for use in dual-mode optical thermometry and dual-functional lighting sources.