(Invited) Influence of Vibrations on the Emission Properties of Single Graphene Quantum Dots
Abstract
Recent years have shown an increasing number of studies dedicated to new light emitters for diverse applications such as optoelectronics, bio-imaging, and quantum technologies. In this context, graphene quantum dots (GQD) have important assets since bottom-up chemistry allows complete control of the structure, opening the way to wide customization of their electronic, optical, and spin properties [1-3]. The full benefit from these opportunities requires addressing GQD’s intrinsic photophysical properties.To do so, single molecule photoluminescence experiment is a powerfull tool [4]. Here, we highlight the influence of vibrations on GQDs’ optical properties, by comparing optical studies to extensive DFT/TDDFT calculations combined with molecular dynamics simulations. Specifically, we discussed their role in the transitions' oscillator strengths [5]. In order to get deeper in the photophysics of GQD, we investigate the spectroscopy of single GQDs at cryogenic temperatures. In particular, we show a narrowing of the emission lines at low temperature, that allows us to characterize and identify vibrational replicas that are characteristic to GQDs [6]. [1] M. G. Debije, J. Am. Chem. Soc . 2004, 126, 4641 [2] X. Yan, X. Cui, and L.-s. Li, J. Am. Chem. Soc . 2010 132, 5944 [3] A. Konishi et al , J. Am. Chem. Soc. 2010, 132, 11021 [4] S. Zhao et al , Nature Communications , 2018 , 9, 3470 [5] T. Liu et al , under review [6] T. Liu et al , in preparation