Artificial mimics of light-harvesting organic pigment via a double-perovskite structure (LiLa2SbO6:Bi3+, Mg2+, Mn4+) with single-composition and structure-activity relationship

Green photosynthetic pigments play a major role in light-harvesting for biological substances and bio-mimetic strategy will provide a structural or functional model for natural antenna system . But the precise supramolecular structure of chlorosome has still not been clearly identified and the simulation of its function with new alternatives will be a real challenge. It has been well accepted that blue and far-red light are responsible for photosynthesis and photomorphogenesis in the process of plant growth. In this work, a series of single-composition LiLa 2 SbO 6 (abbreviated as LLSO): x Bi 3+ , y Mg 2+ , z Mn 4+ phosphors with double perovskite‐type structure and the evaluation as blue and far-red dual-emission light for plant growth light-emitting diodes (LEDs) have been reported via a high-temperature solid-state reaction method. Under near ultraviolet-light ( n -UV) excitation at 355 nm, intense blue emission (ranging from 360 to 500 nm, 3 P 1 → 1 S 0 ) from Bi 3+ and far-red emission (650–750 nm, 2 E g → 4 A 2g ) from Mn 4+ are found in Bi 3+ -Mn 4+ co-activated LLSO phosphors. To further optimize the photophysical properties, smaller Mg 2+ has been incorporated into Li  +  site in Bi 3+ -doped LLSO phosphor to control blue emission of Bi 3+ . With the increase of Mg 2+ content, an obvious red shift (~15 nm) of Bi 3+ emission band has been detected in the blue region, which is almost overlapped with the absorbance of Chlorophyll- B (around 450 nm). Moreover, the photoluminescence (PL) emission intensity and decay lifetime of Bi 3+ can be improved by substituting Mg 2+ for Li + . These changes should be attributed to the combined effects of the crystal field splitting and the superior lattice rigidity . Finally, the temperature-dependent PL spectra of the composition-optimized phosphor are measured, and the excellent thermal-stable emission (up to 473 K) has been obtained. It has been observed that Bi 3+ blue emission and Mn 4+ far-red emission exhibit different temperature quenching effect and such phosphor can be considered as an ideal candidate in optical thermometry.