Carbon Dots in a Matrix: Energy‐Transfer‐Enhanced Room‐Temperature Red Phosphorescence

Abstract

High‐efficiency red room‐temperature phosphorescence (RTP) emissions have been achieved by embedding carbon dots (CDs) in crystalline Mn‐containing open‐framework matrices. The rationale of this strategy relies on two factors: 1) the carbon source, which affects the triplet energy levels of the resulting CDs and thus the spectral overlap and 2) the coordination geometry of the Mn atoms in the crystalline frameworks, which determines the crystal‐field splitting and thus the emission spectra. Embedding the carbon dots into a matrix with 6‐coordinate Mn centers resulted in a strong red RTP with a phosphorescence efficiency of up to 9.6 %, which is higher than that of most reported red RTP materials. The composite material has an ultrahigh optical stability in the presence of strong oxidants, various organic solvents, and strong ultraviolet radiation. A green‐yellow RTP composite was also prepared by using a matrix with 4‐coordinate Mn centers and different carbon precursors.

Luminescence anti‐counterfeiting: From elementary to advanced

“…Notably, Yu's group confined CDs in zeolitic or open‐framework matrices by a solvothermal or hydrothermal synthesis method and developed a kind of CDs‐based composites with dual emissions of fluorescence and thermally activated delayed fluorescence (TADF) or RTP. [ 52,57 ] As displayed in Figure 3D, the anti‐counterfeiting pattern co‐painted by CDs@zeolite composites and benzil displayed dual‐color fluorescence under the stimuli of UV light, including blue fluorescence of petals and green fluorescence of leaves, while after the UV light was turned off, the green fluorescence of leaves vanished, and the blue fluorescence of petals turned to naked‐eye visible blue TADF. The whole process was visible to naked eyes and did not rely on the FLI system, which was proved to be a more effective and facile luminescence anti‐counterfeiting mode compared with the above‐mentioned luminescence anti‐counterfeiting co‐regulated by excitation light and short fluorescence lifetime.…”

Matrix‐Free and Highly Efficient Room‐Temperature Phosphorescence Carbon Dots towards Information Encryption and Decryption

“…Room‐temperature phosphorescence (RTP) materials, such as organometallic complexes, metal‐free pure organic compounds and carbon dots (C‐dots) have been of great concerns in many applications fields including bioimaging, sensing and information security owing to their characteristic long lifetime afterglow. Among these RTP materials, C‐dots possess a number of distinct merits such as facile preparation, relatively low manufacturing costs, low toxicity, and high luminescence efficiency .…”

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

“…By controlling the amounts of two CDs, ET efficiency varied from 43 % to 73 %, thus modulating TADF emissions from blue to green . Furthermore, CD‐matrix ET process was manipulated by incorporating heteroatom Mn in zeolitic framework, realizing red and yellow‐green RTP emissions in composites by adjusting the coordination of Mn (octahedral or tetrahedral) in zeolitic matrix . Through pre‐design of the CDs with higher triplet state energy, the phosphorescent efficiency and lifetime of red RTP could be improved from 5.7 % to 9.6 %, and from 1.81 ms to 10.94 ms, respectively.…”

“…CDs‐based host–guest systems are facile for realization of energy and electron transfer processes (Figure c). For energy transfer in composites, efficient energy transitions can occur between CDs and metal ions or CDs and CDs . The tight space in porous composites enables them to stay close enough to allow energy transfer, forming efficient pathways from energy donors to acceptors.…”