Ca₂LaTaO₆:Bi³⁺/Mn⁴⁺ Phosphors with High Brightness Far-Red Emitting and Luminescence Enhancement for Plant Growth LED Lights and Temperature Sensor

Abstract

Herein, Bi³⁺/Mn⁴⁺ doped Ca₂LaTaO₆ phosphors with a double-perovskite structure were successfully synthesized with solid-state reaction at high temperature. The photoluminescence (PL) performances were investigated in detail. The blue radiation (∼465 nm) from the Bi³⁺ ion and the red radiation (∼686 nm) originating from the Mn⁴⁺ ion were obtained under 313 nm excitation. Especially, the pathway of energy transfer (Bi³⁺ → Mn⁴⁺) contributes to enhance the red emission intensity (Mn⁴⁺: ∼686 nm) in Ca₂LaTaO₆:Bi³⁺/Mn⁴⁺ system. The PL mechanism of Ca₂LaTaO₆:Bi³⁺/Mn⁴⁺ was analyzed through luminescence lifetimes and PL spectra. Moreover, the emitting bands of Ca₂LaTaO₆:Bi³⁺/Mn⁴⁺ were primarily matched with the absorbing bands of carotenoids and phytochrome P_FR on behalf of plant growth, so the phosphors were suitable for the design of a plant growth light under near-ultraviolet to blue excitation. At last, the optical temperature dependent performances of the Ca₂LaTaO₆:Bi³⁺/Mn⁴⁺ were analyzed with luminescence intensity ratio technology. The sample has presented excellent temperature measuring relative sensitivity (<i>S</i>_R = 2.106% K^-1). The results illustrated that the Ca₂LaTaO₆:Bi³⁺/Mn⁴⁺ phosphor also can be used to develop an optical temperature sensor.