Far-red-emitting Eu3+-doped Ca2SrWO6 double perovskite: Judd–Ofelt analysis and application in plant cultivation lighting

Abstract

Far-red-emitting Eu³⁺-activated Ca₂SrWO₆ double perovskite phosphors, crystallized in a monoclinic phase, were prepared using a high-temperature solid-state reaction. Thorough investigation included structural refinement, surface morphology insights, and detailed photoluminescence (PL) characterization. The materials, when exposed to n-UV light of 396 nm, emit standard Eu³⁺ emissions in the red (616 nm) and far-red (699 nm) spectral region, following ⁵D₀–⁷F_j (j = 1–4) transitions of the activators. These emissions closely match the absorption window of plant phytochromes, demonstrating the suitability of Ca₂SrWO₆:Eu³⁺ as a far-red component for n-UV-pumped phosphor-converted LEDs in horticultural lighting. Emission in the far-red spectral region fulfils the requirements of plant photoreceptors, which then utilize it in photosynthesis. The optimal Eu³⁺ concentration is determined to be 3 mol%. The time resolved photoluminescence (TRPL) studies were incorporated to examine the PL decay characteristics of the phosphors under study. Additionally, insights into radiative properties were investigated using the Judd–Ofelt (J–O) theory. Determination of J–O intensity parameters, Ω₂ and Ω₄, of Eu³⁺ shows favourable radiative properties of the Ca₂SrWO₆:Eu³⁺ phosphors. Furthermore, the robustness of the PL emission at elevated temperatures was discovered via temperature-dependent photoluminescence (TDPL). The CIE color coordinates (0.646, 0.353), with a very high color purity of 92%, show a strong far-red emission response. Hence, the collective results reveal strong potential of the phosphor under study in phosphor-converted light-emitting diodes (pc-LEDs) for plant-growth lighting applications.