Phosphorescence Tuning of Fluorine, Oxygen-Codoped Carbon Dots by Substrate Engineering

Abstract

Exploiting a precise and reproducible phosphorescence tuning strategy is crucial to tailor-design carbon dots (CDs) for premium gradient anticounterfeiting applications. Toward this target, we designed a facile substrate engineering technique to manipulate the phosphorescence of F, O-codoped CDs. Applying phenolic compounds with different numbers of hydroxyl groups as precursors, the contents of the C–O–C groups in CDs are effectively regulated for gaining outstanding phosphorescence performance as well as the introduction of the F-dopant. After excitation using a UV lamp followed by turning it off, the CDs/polyvinyl alcohol matrix can emit bright yellow room-temperature phosphorescence, which may derive from the synergistic effect of C–F and C–O–C in F and O-codoped CDs. After O and F form a bond, many lone pairs of electrons are generated, which is conducive to the excitation of n → π* and promotes the supplementation of triplet excitons. The phosphorescence tuning of CDs is realized by mixing different substrates, which can provide various phosphorescence lifetimes and colors. Discovering the unique properties, F, O-codoped CDs/substrates can be applied in gradient anticounterfeiting applications. This substrate engineering technique, showing unique and reproducibility with high efficiency, may further facilitate the potential applications of CDs.

One-Pot Synthesis of Orange Emissive Carbon Quantum Dots for All-Type High Color Rendering Index White Light-Emitting Diodes

“…Besides, the efficient π conjugated system, together with electron-donating groups (−NH 2 and −OH) and an electron-accepting group (−COOH) on the surface of the O-CQDs originated from the precursors, may form a specific D-π-A structure to account for the robust solvatochromic effect . More importantly, O-CQDs in different solvents exhibit excitation-independent emission with excitation from 360 to 520 nm, which is like the majority of previously reported CQDs. − …”

Metal–Organic Framework-Activated Full-Color Room-Temperature Phosphorescent Carbon Dots with a Wide Range of Tunable Lifetimes for 4D Coding Applications

“…Currently, there is particular attention on phosphorescent CDs that hold superior potential for applications in bioelectronics, optoelectronics, and anticounterfeiting. − Nevertheless, it is challenging to achieve CDs with room-temperature phosphorescence (RTP) because the predominance of accessible thermal decay pathways intends to inhibit triplet exciton transitions. To date, considerable efforts have been devoted to developing various RTP CDs, with the strategies to achieve RTP CDs mainly falling into two categories. − One strategy is based on molecular structure engineering, that is, to enhance spin–orbit coupling by introducing heteroatoms (e.g., N, P, and halogens), aromatic carbonyl groups, or other substituents into the carbon framework to promote the intersystem crossing (ISC) efficiency. − The other route is based on host embedding, that is, embedding CDs in a rigid environment (e.g., polymer and zeolite) that can effectively suppress nonradiative transitions. − However, RTP in CDs developed to date has mainly been restricted to blue or green. − This limited RTP color tunability limits information encryption capacity. Additionally, methodologies to control the lifetime to be tunable in a wide range are lacking, raising additional limitations for advanced 4D coding applications.…”

Utilizing Deep Learning to Enhance Optical Sensing of Ethanol Content Based on Luminescent Carbon Dots

“…While some of the optical characteristics of CDs in terms of their absorption and emission bands may be reminiscent of classical semiconductor quantum dots, the underlying optical processes are different. , Foremost, CDs do not necessarily exhibit the size dependence of optical properties . The optical properties of CDs are instead frequently determined by the presence of molecular fluorophores or by doping with elements such as nitrogen, fluorine, and oxygen . Also, while there recently have been successful examples to reduce the full width at half-maximum (FWHM) of their emission band, CDs generally exhibit PL with a rather broad FWHM exceeding 50 nm .…”