Promising deep‐red emitting Cr3+‐doped SrAl12O19 phosphors for plant growth LEDs

Abstract

AbstractRecently, deep‐red‐emitting phosphors that can be excited by ultraviolet (UV) and near‐ultraviolet (NUV) light have been extensively investigated for plant growth LED applications. However, due to the harmful effects of these high‐energy rays on plants, violet‐ or blue‐excited deep‐red‐emitting phosphors are considered a more appropriate solution. In this work, SrAl12O19:Cr3+ phosphors were synthesized using a simple solid‐state reaction, revealing a strikingly sharp deep‐red emission band centered at 694 nm and effective excitation by violet light. The optimal SrAl12O19:1.0%Cr3+ phosphor, annealed at 1500°C, exhibits an extended lifetime of 0.549 ms, an energy activation level of 0.239 eV, a good quantum efficiency (QE) of 36.2%, and superior color purity at 100%. Further, an LED prototype with a precise absorption spectrum for far‐red phytochrome (Pfr) has been demonstrated. These results indicate that the synthesized SrAl12O19:1.0%Cr3+ phosphors could be used as a promising deep‐red‐emitting phosphor for plant growth LED.