Bi³⁺/Mn⁴⁺ co-activated phosphors for indoor plant growth and temperature sensing

Indoor plant growing requires the creation of artificial light that meets the needs of future agriculture. The majority of research focuses on various phosphors that generate red or far-red light. The enhancement of the blue component in LEDs for plant development is underappreciated. In this work, Bi³⁺/Mn⁴⁺ co-doped CaYAlO₄ phosphors were synthesized. Two distinct emission bands in the blue (400 nm) and deep red (710 nm) regions, corresponding to Bi³⁺ ions and Mn⁴⁺ ions, were observed under 290 nm excitation. Energy transfer efficiency from Bi³⁺ to Mn⁴⁺ ions was confirmed to be ∼75 % by photoluminescence and decay curve measurements. The EL spectra of the manufactured LED device overlap with the absorption spectra of the principal plant pigments, indicating that the synthesised phosphors are promising for indoor plant growth. In a proof-of-concept experiment, the potential of the synthesised phosphors for temperature monitoring was investigated. The smallest percentage temperature variation between prediction and measurement is approximately 0.5 %, indicating that the synthesized materials are also promising candidates for ratiometric temperature sensing.