Recent Progress of Inorganic Phosphors for Artificial Plant Cultivation LEDs

Abstract

Phosphor-converted light emitting diodes (pc-LEDs) have become the promising and ideal supplemental illumination source for modern environment-controlled agriculture due to their efficient and energy-saving, small size, low cost, long lifetime and especially tunable output spectra. The light absorption of photoreceptors such as chlorophyll-a/b and carotenoids in plants photosynthesis dominantly fall in the blue (350-480 nm) and red (600-680 nm) region, while the far red (680-730 nm) light absorbed by phytochrome to adjust flowering and near-infrared (NIR, 800-1100 nm) light responding to photosynthesis bacterium for assisting biological nitrogen fixation of plant roots. To better match with the absorption spectra of plant growth pigments for enhancing the yield and quality of crops, the spectral highly matched pc-LED for plant growth was realized through adjusting the phosphor. The recent research progress on corresponding mono- or multi-color emission phosphors suitable for plant growth pc-LED lamps were reviewed, including the blue, red/far-red, near-infrared, and white or full-color phosphors which can balance plant requirement and human eye comfort. Besides, the strategies of spectral design and the luminescent properties improvement for phosphor are summarized. Notably, the phosphors those do not affect plant rhythms have also been briefly introduced, and the safety of phosphor in vivo for promoting plant growth should be emphasized. Finally, the outlook was stretched on the base of current challenges for plant growth pc-LEDs.