High-Purity Deep Red Emission of Cr³⁺-Doped YAlO₃ Solid Solution with Perovskite Structure for Plant Growth

Efficient and homogeneous doping of Cr3+ (1 at. %) in yttrium–aluminum perovskite (YAlO3, YAP) solid solution was successfully achieved using a high-temperature melting method. The cell structure figure indicates the formation of orthogonally distorted perovskite structure (space group Pbnm) after the substitution of Cr3+ for Al3+ sites, and the Goldschmidt tolerance factor (t = 0.88) reveals the inevitability of the lattice distortion, while Raman spectroscopy confirms the significant enhancement of the local structural disorder. Excitation and emission spectra show that YAP: Cr3+ exhibits bilinear state far-red emission at 724 and 731 nm with 100% color purity, which perfectly matches the absorption peaks (730 nm) of the phytochrome far-red (PFR), which is required for plant photosynthesis. Variable-temperature spectroscopy confirms that the luminescence intensity of the material at 420 K is 48.4% of that at 300 K, with Ea = 0.12 eV, good thermal stability, and a fluorescence lifetime of 29 ms, which is significantly better than that of the conventional garnet system (such as YAG: Cr3+, τ ≈ 3 ms). This finding demonstrates that the high color purity, excellent thermal stability, and luminescence properties of YAP: Cr3+ have great potential for full-spectrum illumination and plant growth control light sources.