Bi3+/Mn4+ co-doped dual-emission phosphors for potential plant lighting

Developing environment-friendly dual-emission phosphors of both blue-cyan and deep-red lights is desirable for the utilized indoor plant lighting research. Notably, the naked 6s and 6p Bi3+ ions are sensitive to the lattice sites, which emit from Ultraviolet (UV) to red lights in various crystal compounds. Meanwhile, the E-2 -> (4)A(2g) transition of Mn4+ ions promises its deep-red light emissions, which satisfies the demand for specific wavelength lights for plants growth. Hence, a Bi3+/Mn4+ co-doped Sr2LaGaO5: Bi3+, Mn4+ (SLGO:Bi3+:Mn4+) phosphor was finally synthesized. The phase, micromorphology and luminescent properties were systematically evaluated. Upon excitation at 350 nm light, dual emissions of both blue-cyan (470 nm) and deep-red (718 nm) lights were observed. Besides, due to the pronounced photoluminescence (PL) spectral overlap between Bi3+ and Mn4+ ions, a potential energy transfer process from Bi3+ to Mn4+ ions was confirmed. The relative PL intensities between Bi3+ and Mn4+ ions can be tuned just by adjusting the Mn4+ ion concentration. Besides, Li+ co-doping has been evidenced to improve the deep-red emissions (718 nm) of SLGO:0.005Mn(4+) due to charge compensation and rationally designed lattice distortion, together with the improved thermal stability. Finally, the emissions of SLGO:Bi3+, Mn4+, Li+ phosphor suit properly with the absorption of the four fundamental pigments for plant growth, indicating that the prepared phosphorescent materials may have a prospect in plant light-emitting diodes lighting.

Automated summary

In this study, an environmentally friendly phosphor emitting both blue-cyan and deep-red lights was successfully synthesized by co-doping Bi3+ and Mn4+ ions. The emission properties could be tuned by adjusting the concentration of Mn4+ ions and Li+ co-doping. The prepared phosphor showed potential applications in plant light-emitting diode lighting.