Photoluminescence of carbon-based nanomaterials: Fullerenes, carbon nanotubes, graphene, graphene oxide, graphene and carbon quantum dots

Abstract

Apart from unique physical, chemical, mechanical and thermal properties, carbon-based nanomaterials exhibit unusual optical behavior. Photoluminescence (PL) of these materials is particularly interesting considering that bulk carbon materials such as graphite and diamond do not show luminescent properties. The subject of the chapter is fullerenes, carbon nanotubes, graphene, graphene oxide, graphene and carbon quantum dots. In this chapter, firstly the general physical and chemical properties of different carbonbased nanomaterials are presented, such as the crystalline structure, morphology and chemicals composition. Difference between dimensionality, type of hybridization of C atoms, the level of oxidation, size and shape are explained considering that these are key characteristics which determinate the optical behavior of these materials. In the following part of chapter, the origin of PL in different carbonbased nanomaterials, mechanisms and the tunability of the photoluminescence properties are discussed: exciton pairs which lead to PL of carbon nanotubes, defect centers such as of impurities or vacancies in nanodiamonds, different size of conjugated π-domains in reduced graphene oxide, suggested mechanisms of PL for graphene quantum dots, surface chromophores and defects in carbon quantum dots, etc. The PL properties such as emission spectra, excitation wavelengths, PL lifetimes as well as PL quantum yields are compared between different carbon-based nanomaterials. Furthermore, the parameters which affect these PL properties are argued. Additionally, the possibilities of application of carbon-based nanomaterials due to its PL properties are analyzed. Taking into account other physicochemical as well as PL properties, the most promising applications are highlighted, such as in bioimaging, drug delivery, sensing, in organoelectronic devices and others.