Effect of defects on quantum yield in blue emitting photoluminescent nitrogen doped graphene quantum dots

Kharangarh, Poonam R and Umapathy, Siva and Singh, Gurmeet (2017) Effect of defects on quantum yield in blue emitting photoluminescent nitrogen doped graphene quantum dots. In: JOURNAL OF APPLIED PHYSICS, 122 (14).

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Abstract

This paper presents a comprehensive study of the impact of defects on quantum yield in Nitrogen doped graphene quantum dots (N-GQDs). The facile and high yielding hydrothermal method was used to process the N-GQDs by selecting two different nitrogen containing powders, that is, NH4Cl (sample-I) and (NH4)(2)SO4(sample-II). Initially, the synthesized samples were characterized by using High Resolution Transmission Electron Microscope (HRTEM), Powdered X-Ray Diffraction, Raman Spectroscopy, and UV-Visible spectroscopy, Fourier Transform Infrared Spectroscopy, and Photoluminescence (PL) for sample integrity. HRTEM images suggest that the majority of the both sample types were in the narrow range of 5-20 nm in diameter. The samples show blue photoluminescence and excitation dependent PL emission characteristics. As expected, by using the different excitation energy in PL, appearance of peak introduces additional energy levels between pi and pi* that provide alternative electron transition pathways. The most remarkable finding is that the fluorescence quantum yield is up to 28% for sample-I and is 49.8% for sample-II, which is higher than that of reported GQDs (less than 25%). This clearly suggests that the defect states related to Nitrogen, Chlorine, and Sulfur that alter the band gap of the GQDs determine the PL characteristics and the quantum yield. Published by AIP Publishing.

Item Type:	Journal Article
Publication:	JOURNAL OF APPLIED PHYSICS
Additional Information:	Copy right for this article belongs to the AMER INST PHYSICS, 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	03 Nov 2017 10:46
Last Modified:	03 Nov 2017 10:46
URI:	http://eprints.iisc.ac.in/id/eprint/58151

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