Spectral engineering of Mn4+/Ba2+ co-doped perovskite phosphors for high-performance plant cultivation LED

Oxide perovskite phosphors (ABO 3 -type) are promising light-conversion materials for controlled-environment agriculture, but their large indirect bandgaps (3.0–4.7 eV) and strong thermal quenching limit radiative efficiency and stability. In this study, a dual-site engineering strategy is applied to LaMg 0.5 Sn 0.5 O 3 , where partial substitution of Ge 4+ for Sn 4+ yields a wide-bandgap LaMg 0.5 Ge 0.3 Sn 0.2 O 3 host (E g ≈ 3.7 eV). Density functional theory (DFT) and experimental characterizations confirm that Mn 4+ doping introduces mid-gap states, enabling efficient, host-decoupled far-red emission (∼703 nm) via the 2 E → 4 A 2 transition. Ba 2+ co-doping further enhances the emission intensity by 1.67-fold via charge compensation. The resulting LaMg 0.5 Ge 0.3 Sn 0.2 O 3 :Mn 4+ , Ba 2+ phosphor exhibits intense and narrow far-red emission (FWHM = 20 nm), a peak internal quantum efficiency of 98.8%, and thermal stability with 78.9% emission retention at 150 °C. Its emission spectrum aligns well with the absorption profiles of phytochrome Pfr and chlorophyll b, facilitating enhanced photosynthetic response. In proof-of-concept garlic cultivation trials, the fabricated far-red phosphor-converted LEDs demonstrated the capability to effectively promote biomass accumulation and morphological development under a time-segmented lighting schedule. This dual-doping approach provides a versatile design framework for high-performance far-red phosphors in sustainable agriculture lighting. • Dual-site modified LaMg 0.5 Sn 0.5 O 3 perovskite phosphors were developed for plant lighting environments. • Synergistic effects of Mn 4+ and Ba 2+ doping reduce the indirect bandgap and enhance radiative recombination efficiency. • Ge 4+ substitution strengthens the perovskite framework and suppresses oxygen vacancy to prevent collapse. • The pc-LEDs outperform continuous all-night far-red lighting in biomass promotion while reducing energy consumption.