Far red and near infrared double-wavelength emitting phosphor Gd2ZnTiO6: Mn4+, Yb3+ for plant cultivation LEDs

摘要

Far-red (FR) and near-infrared (NIR) double-wavelength emitting phosphors Gd2ZnTiO6: Mn4+/Yb3+ (GZT: Mn4+/Yb3+) used for light-emitting diodes (LEDs) towards plant cultivation have been synthesized via convenient high-temperature solid-state reaction method. Their structures and luminescent properties were identified by powder X-ray diffraction (XRD) and photoluminescence excitation (PLE) and emission (PL) spectra. The crystal field strength of Mn4+ -occupied octahedra [TiO6](8-) environment was estimated according to the PL and PLE spectra of the Mn4+ solely doped GZT. Under near ultraviolet light (n-UV) excitation, intense FR emission (ranging from 650 to 720 nm) from Mn4+ and NIR emission (925-1075 nm) from Yb3+ were achieved in Mn4+-Yb3+ co-doped samples, which matches well with the absorption spectra of the phytochrome P-FR and photosynthetic bacteria, respectively. The energy transfer processes from Mn(4+ )to Yb3+ in GZT: Mn4+/Yb3+ were also investigated in detail, and the FR/NIR intensity ratios could be tuned by adjusting the concentration of Mn4+ and Yb(3+ )to meet the requirements of different species of plants and bacteria. Results indicated that the present GZT: Mn4+/Yb3+ phosphors possess great potential applications in plant cultivation LEDs.