Synthesis and photoluminescence properties of a novel Ca₂LaNbO₆:Mn⁴⁺ double perovskite phosphor for plant growth LEDs

In this paper, a series of Ca₂LaNbO₆ (CLN):Mn⁴⁺ far-red phosphors with different doping concentration were successfully prepared by traditional high temperature solid state method at 1250 °C. The samples were characterized and analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence excitation (PLE) spectra, photoluminescence (PL) spectra, ultraviolet–visible diffuse reflectance spectra (UV–Vis DRS), temperature-dependent emission spectra and internal quantum efficiency (IQE). The particle size of CLN is < 3 μm. The strongest excitation peak of CLN:Mn⁴⁺ phosphors lies at 352 nm, which is attributed to the ⁴A_2g → ²T_2g transition of Mn⁴⁺ ions. The sample has a strong emission peak at 684 nm, which corresponds to the ²E_g → ⁴A_2g energy level transition of Mn⁴⁺ ions. The optimum doping concentration of the sample is 0.03 mol%, and the quenching mechanism is dipole–quadrupole interaction. In addition, the thermal activation energy of the sample was calculated to be 0.368 eV. Importantly, under the excitation of near-ultraviolet light at 365 nm and driven by 25 mA current, the LED with CLN:0.0003Mn⁴⁺ emits bright far-red light. All the results indicated that CLN:Mn⁴⁺ phosphors have potential application value in indoor plant cultivation.