Sonochemical Synthesis of Carbon Dots/Lanthanoid MOFs Hybrids for White Light-Emitting Diodes with High Color Rendering

Abstract

Although lanthanoid metal–organic frameworks (Ln-MOFs) have been widely developed for white light-emitting diodes (WLEDs), the color rendering index (CRI) values are still lower than 80. To overcome this limitation, a series of CDs/Ln-MOFs hybrids, namely, CDs-2@Ln-MOF, CDs-3@Ln-MOF, and CDs-4@Ln-MOF containing blue-emitting CDs and yellow-emitting bimetallic [(Eu1.22Tb0.78(1,4-phda)3(H2O)]­(H2O)2 were prepared via sonication at room temperature to restrict the self-quenching of CDs in composite materials. The as-synthesized composite materials were investigated by Fourier transform infrared, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and photoluminescence. The luminescent color of the materials can be adjusted by varying the amount of CDs and excitation wavelengths. The resulting CDs-3@Ln-MOF achieved excellent CRI up to 93 with the ideal Commission International ed’Eclairage coordinate (0.334, 0.334) and appropriate correlated color temperature (CCT) (5443 K). In addition, the tunable multicolored luminescence based on single and bimetallic Eu x Tb2–x (1,4-phda)3(H2O)]­(H2O)2, x = 0, 0.73, 1.22, 1.57, 1.94, and 2, were applied as the luminescent security inks for anti-counterfeiting application through encoding/decoding and rewritable data.

Conductive MOFs with Photophysical Properties: Applications and Thin-Film Fabrication

“…CDs-2, CDs-3, and CDs-4 refer to 2, 3, and 4 mL of CDs encapsulated into MOFs, respectively. Reprinted with permission from Ref [63]…”

Energy Transfer in Metal–Organic Frameworks and Its Applications

“…Very recently, the issue of the low color‐rendering index (CRI) of Ln–MOFs, which is caused by the low EnT efficiency from the ligand to the Ln 3+ ions, was solved by combining carbon dots (CDs) with yellow‐emitting bimetallic Ln‐MOFs to modulate single‐phase white‐light emission. [ 98 ] In the study, the as‐prepared composites exhibit a very high CRI of 93, which is a vast improvement for this type of Ln 3+ ‐based phosphor ( Figure ).…”

Carbon Dots in Porous Materials: Host–Guest Synergy for Enhanced Performance

“…To enrich the functionalization of CDs@MOF composites, other nanodots (e.g., quantum dots (QDs), Fe 3 O 4 ) or luminescent Ln n+ ions (e.g., Eu 3+ , Tb 3+ ) were also encapsulated into MOFs along with CDs . For instance, CDs@Eu‐MOFs were constructed by embedding blue emissive N,S‐CDs into red emissive Eu‐MOFs, exhibiting unique dual‐emissive PL property (Figure a); CDs@Ln‐MOFs were built by loading CDs into Eu 3+ and Tb 3+ bimetallic centered MOFs presenting multi‐color emissions …”

“…b) CDs@Ln‐MOFs coated on UV‐LED chip utilized in LED lighting. Reproduced with permission . Copyright 2019 American Chemical Society.…”

“…As shown in Figure b, a CDs‐3@Ln‐MOF composite exhibited white light emission by combining blue emissive CDs and yellow emissive Ln‐MOF. When coating on a commercial 365 nm UV‐LED, it showed high color rendering index up to 93, ideal Commission International de I′Eclairage coordinate (0.334, 0.334) and appropriate correlated color temperature (5443 K) as “cool color” indoor lighting . Furthermore, the CDs‐based afterglow materials have demonstrated promising potential in supplementary lighting field.…”