A novel ultra-broadband red LaGeSbO6:Mn4+ phosphor with excellent responsiveness to phytochrome PFR for plant growth

Broad red emitting phosphors are essential for the growth of indoor plants. Previous Mn4+-activated far-red phosphors typically displayed narrow emission, which could not well overlap with plant pigment absorption. A high temperature solid state technique was used to create the unique double perovskite LaGeSbO6:Mn4+ phosphor with an emission peak centered at 700 nm and an impressive full width at half maximum (FWHM) of 100 nm. The origin of ultra-broadband emission of LGS:Mn4+ phosphors was confirmed by crystal structure and time-resolved spectra owing to the occupation of the two octahedral [SbO6] and [GeO6] centers by the Mn4+ ion. The quenching mechanism is brought about by the dipole-dipole interaction. The broadband emission is sub-stantially broader than that of other Mn4+-activated red emitting phosphors previously described. Besides, the emission spectrum of LaGeSbO6:0.4%Mn4+ matches well with the phytochrome PFR absorption band for plant development. All of the findings suggested that the novel LaGeSbO6:Mn4+ phosphor could be potentially used in light-emitting diodes for indoor plant culture.