[12p-D511-1~13] 【CS.6】 Code-sharing Session of 8.3 & 9.2 & 13.6

▲ [12p-D511-5] Insight of highly luminescent C-quantum discs produced by plasma.

〇Svrcek Vladimir¹, Slavia Deeksha Dsouza^1,2, Marius Buerkle¹, Davide Mariotti² (1.AIST, Central 2, Umezono 1-1-1, Tsukuba, JAPAN, 2.Ulster University)

Keywords:carbon-quantum discs, microplasmas

Carbon nanoparticles can be alternative to semiconductor nanocrystals as next generation green nanomaterials and can be roughly divided into several subgroups, such as graphene dots, graphite dots, amorphous carbon dots, polymer-like dots, and so on. In particular, carbon quantum dots shown ample photoluminescence (PL) at room temperature whereby the crystalline carbon dots seem to be superior to the amorphous one. It has to be noted that the exact mechanism of the PL of remains unsettled and despite their nanometer size (< 10 nm), nevertheless, one should be cautious in the use of the “quantum confinement effect” , as the PL shifts do not necessarily represent a real quantum confinement effect. In the current work, direct current microplasmas serve as a synthesis method for tuning the optical properties of carbon-quantum discs in colloidal solution. Thus from TEM and AFM results we can infer that these nanoparticles are not nanoparticles or dots but actually discs formed by 4-12 layers of graphene with the mean height varied between 1.3 to 4.3 nm. The lattice spacing calculated using fast Fourier transform, was found be about 3.3 Å which is (002) plane spacing reported for graphite (3.3 Å) and sometimes discs contains spacing close to 2.42 Å reported to be lattice plane of graphene. Here we discuss the possible synthesis mechanisms and potential chemical pathways leading to the formation of the discs. Furthermore, high photoluminescence quantum yield (33% to 68%) and PL maxima tuning as a function of the synthesis conditions is exploited for optoelectronic and photovoltaic applications. We argue that the PL of carbon quantum discs with a well-defined crystalline core is however related to the size or conjugated domains of carbon dots/nanoparticles, while, in most cases, the quantum size effect seems to not work and the related PL emission is mainly influenced by the oxygen/nitrogen defects and surface state.