Novel rare earth free phosphors CsMg2P3O10: Mn2+ with efficient and ultra-broadband red emission for plant growth LEDs

An efficient and ultra-broadband red phosphor CsMg2P3O10: Mn2+ (CMPO: Mn2+) is first synthesized toward indoor plant growth LEDs. The phase purity, element composition, crystal, and local electronic structure are explored to discuss the structure and photoluminescence properties. Structure refinement and series X-ray diffractometer (XRD) results show that CMPO: Mn2+ is well crystallized in an orthogonal crystal system. The diffuse reflection and excitation spectra show that CMPO: Mn2+ has strong absorption around near ultraviolet region, assigned to the [(6)A(1) -> E-4(D-4), T-4(2)(D-4), [(4)A(1)((4)G), E-4((4)G)], and T-4(1)((4)G)] transitions of Mn2+, respectively. Upon 415 nm excitation, an efficient red emission centered at 647 nm with ultra-broad full width at half-maximum (FWHM similar to 100 nm) and high quantum efficiency (IQE similar to 44.3 %) is observed, and because of the ultra-broad FWHM, the red emission is well accordant with the absorption spectra band of phytochrome P-R and P-FR. The optimal doping contents, lifetime as well as interaction mechanism of CMPO: Mn2+ are discussed in detail. Finally, the excellent thermal stability (84.5% @ 140 degrees C) and related thermal quenching mechanism of CMPO: Mn2+ are discussed. The above results indicate that CMPO: Mn2+ phosphors have great potential for application in plant growth LEDs.