Color-Tunable and High-Efficiency Dye-Encapsulated Metal–Organic Framework Composites Used for Smart White-Light-Emitting Diodes

Abstract

Luminescent metal-organic frameworks (MOFs) (typically dye-encapsulated MOFs) are considered as one kind of interesting downconversion materials for white-light-emitting diodes (LEDs), but their quantum efficiency (QE) is not sufficient and thus needs to be significantly enhanced for practical applications. In this study, we successfully synthesized a series of Rh@bio-MOF-1 (Rh = rhodamine) with an internal QE as high as ∼79% via a solvothermal reaction followed by cation exchanges. The high efficiency of the Rh@bio-MOF-1 composites was attributable to the high intrinsic luminescent efficiency of the selected Rh dyes, the confinement effect in the bio-MOF-1 host, and the uniform particle morphology. The emission maximum could be continuously tuned from 550 to 610 nm by controlling the species and concentration of encapsulated dye molecules, showing great color tunability of the dye-encapsulated MOFs. The emission lifetime of ∼7 ns was 1 or 2 magnitude orders shorter than that of Ce- or Eu-doped inorganic phosphors, allowing for visible light communication (VLC). White LEDs, fabricated by using the synthesized Rh@bio-MOF-1 composite and inorganic phosphors of green (Ba,Sr)SiO:Eu and red CaAlSiN:Eu, exhibited a high color rendering index of 80-94, a luminous efficacy of 94-156 lm/W, and an excellent stability in color point against drive current. The Rh@bio-MOF-1 composites with tunable colors, short emission lifetime, and high QE are expected to be used for smart white LEDs with multifunctions of both lighting and VLC.

White‐Light Emission from Dual‐Way Photon Energy Conversion in a Dye‐Encapsulated Metal–Organic Framework

“…[1][2][3][4] Up to now,enormous materials have been developed to possess WLE performance,i ncluding carbon quantum dots, [5] polymers, [6][7][8] perovskites, [9][10][11][12] metalorganic materials, [13][14][15][16][17][18][19][20][21][22] and so on, providing great promise in solid-state lighting (SSL), anticounterfeiting,s ensing and detecting,a nd so on. [1][2][3][4] Up to now,enormous materials have been developed to possess WLE performance,i ncluding carbon quantum dots, [5] polymers, [6][7][8] perovskites, [9][10][11][12] metalorganic materials, [13][14][15][16][17][18][19][20][21][22] and so on, providing great promise in solid-state lighting (SSL), anticounterfeiting,s ensing and detecting,a nd so on.…”

“…Alternatively, WLE can also be achieved by photon up-conversion process, applying NIR excitation with low photon energies.However, such implementation has so far been restricted in rare-earth-doped inorganics,w hich are facing the urgent problem of scarce resources and environmental issues. [17][18][19][20][21][22] Yet, owing to the different two-photon absorption and conversion abilities,t he output emitting spectral ratio from MOF and dyes might be different in TPAand OPAprocesses even with the same host-guest compositions.T his adds further difficulty in getting WLE by TPEF blending method. Such emission undergoes atwo-photon absorption (TPA) process,b earing the advantages of deeper tissue penetration, tight focusing area, reduced autofluorescence, and improved signal-to-noise ratios.…”

“…White-light-emitting (WLE) materials have attracted continuous attention for their fundamental importance and practical implication. [1][2][3][4] Up to now,enormous materials have been developed to possess WLE performance,i ncluding carbon quantum dots, [5] polymers, [6][7][8] perovskites, [9][10][11][12] metalorganic materials, [13][14][15][16][17][18][19][20][21][22] and so on, providing great promise in solid-state lighting (SSL), anticounterfeiting,s ensing and detecting,a nd so on. In these materials,w hite-light emission is generally produced by aUV-excited one-photon absorption (OPA) process with energy down-conversion.…”

Rare‐earth‐free Li5La3Ta2O12:Mn4+ deep‐red‐emitting phosphor: Synthesis and photoluminescence properties

“…Compared to the fuel-burning lamps, incandescent light bulbs, and fluorescent lamps, the light-emitting diodes (LEDs) as the fourth-generation lighting source have attracted many attentions because of their performance advantages, such as the energy-saving, long lifetime, highly luminous efficiency, material hardness, and harmlessness to environment. [1][2][3] The LED lighting may be fabricated by two methods, such as the semiconductor materials combination and the combination via phosphors with LED chip. The latter has been deemed to be the meritorious lighting source in the lamp industry and is being used in many fields, such as the traffic signals, mobile phones, indoor plant growth, and daily life.…”

“…Mn 4+ -doped oxides have the excitation spectral band located at 220-570 nm and show red emission in the region from 640 to 790 nm with the different emission peak positions due to the crystal field influences of oxides. Mn 4+ -doped oxides have reported widely, such as La(MgTi) 1 42 From the description above, it is known that oxide matrix is one of important influencing factors on luminescence properties of Mn 4+ ion. Li 5 La 3 Ta 2 O 12 (LLTO) based oxides with garnet structure has a cubic crystal system with the space group of Ia3d (230) and good ionic conductivity, and has been researched in the lithium ionic battery fields.…”