Mn4+-activated red pc-LED for precisely matching the spectral absorption and circadian rhythm of photoreceptor toward promoting crop growth

Phosphor-converted light-emitting diode (pc-LED) technology, as artificial lighting source, is the most promising option for providing power for plant growth in future smart agricultural factories. However, developing red phosphors with the desired emission spectral range and good thermal stability is still experimental. In this study, an Mn4+-doped BaZrGe3O9 red-emitting phosphor with remarkable thermal stability is reported. The red emission, spanning the wavelength range of 600–800 nm, matches the absorption range of chlorophyll a, b and phytochrome (Pr). Its good thermal stability at 150 °C is in addition to its emission intensity, which is 81.7 % of its room-temperature intensity. Co-doping with Ca2+ contributes to a 1.7-fold increase in the red emission intensity at room temperature. The encapsulation of the present phosphor onto UV LED chips produces red emitting LED devices, which can be used for garlic and corn cultivation. The implementation reveals that the six-hour artificial red light illumination supplement is the most effective and significant means to promote garlic and corn growth. The as-obtained red-emitting phosphor may be a promising candidate for pc-LEDs promotion of crop growth in agricultural factories.