Photoluminescence Mechanism of Carbon Dots: Triggering Multiple Color Emissions through Controlling the Degree of Protonation

Abstract

Carbon dots (CDs) have excellent optical properties, low toxicity and easy preparation, which have led to them being widely used in biomedicine, sensing and optical devices. However, although great progress has been made in the preparation of CDs, the detailed exploration of their photoluminescence (PL) mechanism is still under debate due to their complex structures and surface functionalities. Here, we proposed a single change in the pH of the synthesis condition, which had no effect on the CDs intrinsic core states and avoided the mutual influence of multiple PL origins. The m-phenylenediamine (m−PD) served as a carbon source, whose protonation degree determined the surface state of the resulting CDs and the accompanying fluorescence characteristics. The as-obtained CDs materials can be applied in the chemical sensor and anti-counterfeiting fields in a targeted manner. Therefore, our work not only contributes to the explanation of the CDs PL mechanism, but also obtains a series of CDs materials with controllable PL properties.

Selective identification of p-nitroaniline by bromine-mediated polarization of carbon dots

“…1F), which are attributed to the C-C/CvC, C-O and CvO groups, respectively. 32 The O 1s bond (Fig. 1G) shows four characteristic peaks at 531.2, 532.0, 532.7 and 533.6 eV, which belong to B-O-B, CvO, C-O-C/C-OH and O-CvO groups, respectively.…”

Photoluminescent carbon nanodots for artificial photosynthesis

“…In some instances, a supplementary shoulder peak near 450 nm can be observed due to the presence of COOH groups [69] Despite all the significant advancements in understanding the photoluminescence (PL) mechanism of CDs, the detailed and exact mechanism remains a subject of exploration due to the complexity of the structures and surface functionalities. Different factors may add especially the surface state, carbon core state, and molecular state have been proposed to expound the PL mechanism [70][71][72][73]. To understand the PL mechanism, researchers have explored the relationship between CDs' surface chemical bonds and their optical properties.…”

Large-Scale Synthesis of Tunable Fluorescent Carbon Dots Powder for Light-Emitting Diodes and Fingerprint Identification

“…LEDs have become popular lighting devices because of several advantages, including their adjustable spectrum, long life, and high efficiency [41,42]. Based on the excellent solid-state fluorescence properties of the prepared series of CDs, a variety of LEDs can be fabricated using CDs as the luminescence conversion layer, including multi-color LEDs and white LEDs.…”