Facile Preparation Strategy of Novel Carbon Dots with Aggregation‐Induced Emission and Room‐Temperature Phosphorescence Characteristics

Abstract

molecules and metal quantum dots (QDs). [1] So far, CDs have been explored in various fields, such as light emitting devices, [2] fluorescent cellular imagination, [3] anti-counterfeiting, [4] and visualized tumor therapy. [3a,5] However, further development and application of CDs have been limited by the aggregation-caused quenching (ACQ) of solid-state fluorescence (SSF) from the direct π-π stacking. [6] As opposed to the phenomenon of ACQ, aggregation-induced emission (AIE) effects were first reported by Tang et al. [7] In recent years, AIE CDs-based materials have been reported and several rational strategies have been proposed to generate and enhance the fluorescence in the aggregation state. [1a,8] However, CDs with dual emission peaks always fail to show AIE effects, and CDs achieving AIE especially red/orange fluorescence exhibit only single emission peak in solid state. [8b,9] Hence, the development CDs with dual emission, or even multi-emission peaks and embedded AIE effects can lead to significant breakthrough in extensive application fields such as LEDs and information encryption.More interestingly, the room-temperature phosphorescence (RTP) characteristic of CDs has been discovered recently, [10] which makes CDs highly potential in many fields of practical applications, including bioimaging, optoelectronic devices, and information security/protection. [11] Despite the efforts devoted to developing RTP CDs, [11b,12] most current RTP materials exhibit phosphorescence only in their solid anhydrous states, in which CDs can be fixed by the matrix. Phosphorescence quenching typically takes place in the presence of water as water molecules usually break up hydrogen-bonding interactions between CDs and matrices. [13] As a result, the aqueous application of RTP materials is significantly hindered, particularly in the fields of multi-information encryption. [14] Therefore, as more as we know, it is very challenging to achieve both dual fluorescence emission AIE and RTP in aqueous state.From this perspective, carbon dots named E-CCDs with dual emission luminescence and RTP characteristic are synthesized by an eco-friendly, low-cost one-pot solvothermal method. E-CCDs exhibit blue fluorescence when well-dispersed in organic solvents, then change to red fluorescence when water is added, which also have a long phosphorescence lifetime. The As one of the most promising fluorescent nanomaterials, carbon dots (CDs) are extensively studied. Nevertheless, one-pot synthesis methods for CDs with both dual emission aggregation-induced emission (AIE) and roomtemperature phosphorescence (RTP) could lead to significant breakthrough in extensive application fields. Herein, a new class of CDs (E-CCDs) with reversible luminescence (blue dissolved fluorescence and red AIE) and RTP behavior is obtained with an eco-friendly, low-cost one-pot solvothermal method. E-CCDs exhibit dual fluorescence emission at 460 (Em-1) and 600 nm (Em-2), which is related to different emission centers. The addition of cyanic acid enhanc...

Carbon Dots@Allophane Core–Shell Nanoparticles with Long-Lifetime Room-Temperature Phosphorescence for Anti-Counterfeiting Applications

“…This energy difference can sufficiently enable ISC and produce effective phosphorescence. 42 To validate the hypothesis that the phosphorescence luminescent center of CDs@Allophane is CDs embedded in Allophane, several samples were prepared including pure Allophane, CDs@Allophane-PVP, and CDs@Allophane-glucose. As shown in Figure S6, pure Allophane does not exhibit any light emission under UV irradiation, confirming that Allophane, as a matrix, constrains CDs.…”

“…As shown in Figure e, the Δ E ST between S 1 and T 1 is 0.2 eV ( S 1 = 2.59 eV and T 1 = 2.39 eV). This energy difference can sufficiently enable ISC and produce effective phosphorescence …”

Modulating multi-color room temperature phosphorescence emission for carbon dot composites with ultralong lifetime

“…Carbon dots, as zero-dimensional carbon-based nanoluminescent materials, have aroused enormous interest because of their low toxicity, facile synthesis, biocompatibility, high stability, and tunable optical properties. [14][15][16][17][18][19][20][21][22] In general, the optical properties of RTP CDs can be enhanced effectively by heteroatom doping that include F, 23 N, 24 P, 25 S, 26 etc. Besides, matrix-assisted synthesis is another important method to obtain RTP CDs by embedding CDs into a matrix such as cyanuric acid, 27 SiO 2 , 28 melamine, 29 polyvinyl alcohol (PVA) 30 and so on.…”

Time‐dependent Phosphorescence Color of Carbon Dots in Binary Salt Matrices through Activations by Structural Confinement and Defects for Dynamic Information Encryption

“…Carbon dots (CDs) is a rising star in luminescent materials due to their low cost, [11] nontoxic [12,13] and easily synthetic approach, [14] which can show room temperature phosphorescence (RTP) by incorporating into a solid host matrices, [15][16][17] including organic materials (such as, poly (vinyl alcohol) [18][19][20] and polyurethane [21] ) and inorganic materials (such as KAl(SO 4 ) 2 •x(H 2 O), [22] layered double hydroxides, [23] amorphous silica [24,25] and zeolites [26][27] ). This provides a clue that the luminescent behavior of CDs can be regulated according to the selection of the host matrices.…”