Achieving high-performance far-red emission in Cr3+-activated garnet phosphors via Ca2+/Zr4+ doping toward plant lighting

Abstract

Equimolar Ca²⁺ and Zr⁴⁺ doping was implemented to establish novel garnet-type Gd_3−xCa_xAl_2.95Ga_2−xZr_xO₁₂:0.05Cr³⁺ (x = 0–2.0) far-red (FR) phosphors. The quantum efficiency and temperature-dependent luminescence analysis successfully produced the optimal x = 0.5 phosphor, which exhibited highly efficient (IQE = 92.8% and EQE = 31.6%) broadband FR-emission peaking at ∼714 nm (full-width at half-maximum ∼81 nm) and excellent thermal stability (95.5% at 423 K) under 450 nm light excitation. Its performance is superior to that of most reported Cr³⁺-activated FR-emitting garnet phosphors, and its emission spectrum can well superpose with the absorption band of the far-red phytochrome, endowing this phosphor with huge potential application in the construction of high-quality FR pc-LEDs used for plant lighting.