Understanding the Photoluminescence Mechanism of Carbon Dots. (23rd June 2017)

• Record Type: Journal Article
• Authors: Jiang, Zhoufeng; Krysmann, Marta J.; Kelarakis, Antonios; Koutnik, Petr; Anzenbacher, Pavel; Roland, Paul J.; Ellingson, Randy; Sun, Liangfeng
• Is Part Of: MRS advances. Volume 2:Number 51(2017)
• Page Start: 2927
• Page End: 2934
• Publication Date: 2017-06-23
• Subjects: absorption, -- luminescence, -- environmentally benign; Electrical engineering -- Congresses; Physics -- Congresses; Materials -- Research -- Congresses; Materials science -- Congresses; 620.11
• DOI: 10.1557/adv.2017.461
• Languages: English
• ISSNs: 2059-8521

Abstract

ABSTRACT: The carbon dots were investigated to reveal their light-emitting mechanism. The fluorescence spectra of carbon dots show typically two different types of photoluminescence: the excitation-independent component in the short wavelength, and the excitation-dependent component in the longer wavelength. The UV-Vis spectrum of carbon dots shows the absorption maximum of 340 nm which should be accredited to the n-π* transition of the carbonyl group in carbon dots. Absolute quantum yields of carbon dots dispersed in Polyvinyl alcohol is around 15% when the excitation wavelength is less than 425 nm, but decreases continuously when the excitation wavelength increases. The decay lifetimes of the carbon dots also show an abrupt change at excitation wavelength 425 nm. Time resolved photoluminescence was implemented from 31K to 291K to study the photoluminescence decay dynamics of carbon dots, resulting in the continuously decreasing of the lifetime as the temperature increases.