Rational Synthesis of Solid‐State Ultraviolet B Emitting Carbon Dots via Acetic Acid‐Promoted Fractions of sp³ Bonding Strategy

Abstract

Carbon dots (CDs) have received tremendous attention for their excellent photoluminescence (PL) properties. However, it remains a great challenge to obtain CDs with ultraviolet (UV, 200–400 nm) emission in solid state, which requires strict control of the CDs structure and overcoming the aggregation‐caused quenching (ACQ). Herein, a new sp3 compartmentalization strategy is developed to meet these requirements, by employing acetic acid to promote fractions of sp3 bonding during the synthesis of CDs. It markedly decreases the size of sp2 conjugating units in the CDs, and shifts PL emission to the ultraviolet B (UVB) region (λmax = 308 nm). Moreover, sp2 domains are well spatially compartmentalized by sp3 domains and the ACQ effect is minimized, enabling the high quantum yield in solid state (20.2%, λex = 265 nm) with a narrow bandwidth of 24 nm and environmental robustness. The solid‐state UVB emissive CDs are highly desired for application in photonic devices. Hence, a demo of UVB light‐emitting diodes is fabricated for plant lighting, leading to a 29% increase of ascorbic acid content in the basil. Overall, a rational and efficient way to construct solid UVB‐CDs phosphors for wide applications is provided.

Boosting efficiency of luminescent solar concentrators using ultra-bright carbon dots with large Stokes shift

“…The signal peaks between 6.0 and 9.0 ppm correspond to aromatic protons. 42,[43][44][45][47][48][49] Obviously, with the introduction of N doping, both five-and six-membered ring forms may be present in the CD structure due to the possible structural changes of the CDs caused by N doping. Therefore, compared with the CDs without N doping, the N-doped CDs have significantly more signal peaks between 6.0 and 9.0.…”

Circularly Polarized Luminescence of Achiral Carbon Dots in Bi‐Solvent Systems Triggered by Supramolecular Self‐Assembly

“…And the picture of ThT‐CDs in EtOH‐H 2 O under 365 nm ultraviolet light showed that the fluorescence intensity began to decrease significantly due to the violent ACQ (aggregation‐caused quenching) effect when f m reached 50 %, which is further demonstrated the existence of aggregated ThT‐CDs (Figure S10) [21] . It can be seen from Figure S11a that with the gradual increase of f m , the fluorescence intensity decreased significantly and appeared red‐shifted, which is due to the ACQ caused by the formation of aggregated ThT‐CDs.…”

“…And the picture of ThT-CDs in EtOH-H 2 O under 365 nm ultraviolet light showed that the fluorescence intensity began to decrease significantly due to the violent ACQ (aggregationcaused quenching) effect when f m reached 50 %, which is further demonstrated the existence of aggregated ThT-CDs (Figure S10). [21] It can be seen from Figure S11a that with the gradual increase of f m , the fluorescence intensity decreased significantly and appeared red-shifted, which is due to the ACQ caused by the formation of aggregated ThT-CDs. More specifically, during the process of f m rising from 80 % to 99 % in EtOH-H 2 O containing ThT-CDs, the fluorescence intensity maintained a decreasing and red-shifted trend at the beginning, while reversely increased when it is close to 90 %, and in the remaining 90-99 % of the rising stage, the fluorescence intensity decreased again and blue-shifted (Figure S11b).…”

Carbon Dots Derived from Tea Polyphenols as Photosensitizers for Photodynamic Therapy

“…Most of the existing first− and second− generation PSs are porphyrins, phthalocyanines, and their derivatives compounds, which are often limited by factors such as poor resistance to photobleaching under light irradiation, heavy metals effect, and low clearance rate from the target tissue [ 8 ]. Carbon dots (CDs) have been presented as a new metal−free carbon nanomaterial due to their abundant surface groups [ 9 , 10 ], superb biocompatibility, good photobleaching resistance, and adjustable optical properties [ 11 ], and many researchers’ works have conducted a series of exploration and attempts at its application in the field of PDT for different types of cancer. Excitingly, it was Ge et al [ 12 ] who discovered for the first time that the synthesized graphene quantum dots (GQDs) have high 1 O 2 yield under light stimulation and are further applied to PDT tumor therapy in living mice.…”