Aliphatic and aromatic amine based nitrogen-doped carbon dots: a comparative photophysical study

Abstract

The quantum confinement effect in nanoscale material is critical not just in the viewpoint of dimensions but also influences their photophysics such as optical, excitonic, and electrical properties compared to their bulk counterpart. This effect makes the semiconducting quantum dots fluorescent with size and band tunability, which is an asset for their applications in sensors, LEDs, solar cells, etc. The current study highlights the synthesis and photo-induced properties of N-doped carbon dots (CDs) from two precursors, one with ethylenediamine (ECDs) and the other with 2-phenethylamine (PCDs). With the use of both microscopic and spectroscopic approaches, we observe distinct changes in the dimensionality and optical properties of the phenylethylamine-induced CD compared to ethylenediamine-based CDs. The aftermath of doping with Zeta potential measurement indicates positively and negatively charged surfaces for ECDs and PCDs respectively. Through different time-resolved PL lifetime and anisotropy measurements, we report that the incorporation of the phenyl ring in PCDs significantly reduces their water solubility, rotational diffusivity, and PL quantum yield compared to that of the ECDs.