Improved luminescence and energy-transfer properties of Ca₁₄Al₁₀Zn₆O₃₅: Ti⁴⁺,Mn⁴⁺ deep-red-emitting phosphors with high brightness for light-emitting diode (LED) plant-growth lighting

For plant-growth lighting, novel deep-red emission phosphors with high brightness were obtained by co-doping Ti⁴⁺ and Mn⁴⁺ into a Ca₁₄Al₁₀Zn₆O₃₅ substrate through a conventional solid-state reaction strategy. The nominal Ca_14-(x+y)/2Al_10-x-yZn₆O₃₅:xTi⁴⁺,yMn⁴⁺ (CAZO:Ti⁴⁺,Mn⁴⁺) phosphors could be excited by both near-ultraviolet (NUV) and blue-light-emitting diode (LED) chips efficiently and exhibited a strong deep-red emission band ranging from 650 nm to 750 nm, which should be the result of the ²E → ⁴A₂ transition inside the [MnO₆]^8- octahedral. Multiple energy transfer from Ti⁴⁺ to Mn⁴⁺ was detected in this CAZO; whereby Ti⁴⁺ and Mn⁴⁺ phosphors were verified to be a result of the dipole-dipole interaction under excitation at 270 nm. LED plant-growth lights were fabricated using the as-prepared nominal Ca_13.825Al_9.65Zn₆O₃₅:0.15Mn⁴⁺,0.2Ti⁴⁺,0.005H₃BO₃ (CAZO:Mn⁴⁺,Ti⁴⁺,H₃BO₃) phosphors pumped by a 460 nm blue-chip; this luminaire could be used to greatly promote the cultivation of succulent plants. Combined with the attractive thermal stability as well as high quantum efficiency (QE) of this phosphor, it was demonstrated that these novel phosphors may be candidate deep-red luminescent materials for LED plant lighting.