Space-Selective Fabrication of Light-Emitting Carbon Dots in Polymer Films Using Electron-Beam-Induced Chemical Reactions

Abstract

Nanocarbon-based materials have excellent properties, including high electrical conductivity as well as charity-dependent optical absorption and luminescence; therefore, the materials are promising in applications for nanoelectric devices, nanophotonics, and so on. Carbon dots (CDs) are one of the carbon materials recently fabricated. Optical properties of CDs have been reported to be similar to those of polycyclic aromatic hydrocarbons (PAHs). For this reason, the CDs are considered to be composed of PAH. Synthesis of CDs has previously been accomplished through hydrothermal synthesis and microwave irradiation. These methods require a long synthesis time, and the processes involve multiple steps. In this study, we developed a fabrication method of CDs in simple and spatially selective ways, by using radical reactions in an organic polymer film with focused electron-beam irradiation. We investigated various organic polymers as reaction materials and found that polystyrene has a higher efficiency for CD formation than other organic polymers investigated. Absorption, photoluminescence, and Raman scattering properties of the electron-beam-irradiated sample were in good agreement with those reported for the CDs. The technique developed in this study is promising for fabricating light-emitting CDs and photonic crystals in a simple and flexible manner.

Photoluminescence from Carbon Dot-Gold Nanoparticle Composites Enhanced by Photonic and Plasmonic Double-Resonant Effects

“…Figure c shows the top views of the fabricated PVA PCs in Figure a and CD-GNP PCs in Figure b. The formation of the CDs is identified by transmission electron microscopy (TEM), absorption spectroscopy, and Raman scattering spectroscopy, as previously reported …”

“…The formation of the CDs is identified by transmission electron microscopy (TEM), absorption spectroscopy, and Raman scattering spectroscopy, as previously reported. 28 The morphology of the fabricated samples was examined by an SEM and an atomic force microscope. properties of the samples were evaluated by dark-field optical microscopy (Ti-U; Nikon) and confocal optical microscopy, respectively.…”

Enhanced and Polarized Photoluminescence from Carbon Dot–Metal Nanoparticle Composites

“…The physical and optical properties of CDs fabricated by electron beam irradiation have been reported previously. 8,9 In this study, the reaction conditions are similar to those of a previous study, 9 except for the precursor materials used. We found from physical and optical characterization of the fabricated CDs that the dimensions and optical properties are similar to the reported values.…”

“…1−4 CDs have been prepared by various methods, such as hydrothermal process, 5 microwave synthesis, 6,7 and electron-beam-induced chemical reactions. 8,9 Nanometric CDs exhibit visible photoluminescence (PL), and their PL spectral properties are controllable by surface substitutions. 10,11 CDs have low toxicity and are biocompatible, and thus are promising for bioimaging applications.…”

“…Nanoassemblies consisting of polyaromatic carbons and graphenes called carbon dots (CDs) have been attracting much attention recently because of their unique optical properties and photostability. − CDs have been prepared by various methods, such as hydrothermal process, microwave synthesis, , and electron-beam-induced chemical reactions. , Nanometric CDs exhibit visible photoluminescence (PL), and their PL spectral properties are controllable by surface substitutions. , CDs have low toxicity and are biocompatible, and thus are promising for bioimaging applications . However, the quantum yield of PL is typically lower than that of semiconductor quantum dots. , To utilize CDs as light-emitting elements for various applications, the PL intensity should be amplified by improving the quantum yield and/or the excitation probability.…”