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Self-trapped Exciton Emission from Carbon Dots investigated by Polarization Anisotropy of Photoluminescence and Photoexcitaion

Abstract

Carbon dots have attracted tremendous attention because of their intrinsic advantages allowing for the opportunity to replace the traditional florescent materials in various application fields. However, until now, the emission mechanism from carbon dots has been still controversial, which largely hinders the extensive exploitation of such materials. Here, we explore systematically the emission essence of carbon dots by using the spectroscopic anisotropy of polarization, electric-field modulation spectroscopy and time-resolved photoluminescence measurements. We probe the momentum evolution dynamics and evaluate the decay process of the photo-excited hot carriers, which manifest distinct characteristics from band edge emission. We provide clear evidence that carbon dots emission originates from radiative recombination of self-trapped excitons where the mobilization of the carriers is largely impeded due to the existence of the strong local potential field and thus the relaxation of the hot carriers is strongly suppressed. Based on the self-trapped exciton model, all the optical properties of carbon dots inferred from both steady-state and time-resolved optical spectroscopy can be interpreted consistently. Our investigation provides an alternative insight into the emission mechanisms of carbon dots which may improve our understanding on these novel materials.

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Publication details

The article was received on 02 Jun 2017, accepted on 04 Aug 2017 and first published on 04 Aug 2017


Article type: Paper
DOI: 10.1039/C7NR03913A
Citation: Nanoscale, 2017, Accepted Manuscript
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    Self-trapped Exciton Emission from Carbon Dots investigated by Polarization Anisotropy of Photoluminescence and Photoexcitaion

    L. Xiao, Y. Wang, Y. Huang, T. N. Wong and H. Sun, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR03913A

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