Theoretical study on electronic and optical properties of chemically gated circum-1-coronene with metal oxide nanoclusters

Abstract

Graphene is a highly versatile material due to their mechanical and electrical properties. It is a 2-dimensional carbon material with 1 atom of thickness fully of conjugated bonding. Because of its structural and bonding con guration some derivatives of graphene as graphene nanoribbons (GNR) has been focused for developing electronic devices at a molecular scale. Molecular electronics is the eld that studies the electronic and thermal properties of single-molecule junctions. It has the goal of developing typical electronic devices, such as diodes, transistors, switches, and thermoelectric devices at the molecular scale. Nowadays, the miniaturization of electronic components has become a challenge for future developments of microprocessors, sensors, and micro-machines. A crucial step to overcome this challenge is to comprehend the behavior of electronic dynamics at a molecular level. On molecular junctions, where the classical system setup is Metal-Molecule-Metal (MMM), several factors can change or gate the charge transport through the device. One of them is chemical gating. Chemical gating is based on modifying the orbital energies of the base molecule through an adsorption or chemical bond with other molecules or reactants. The change in the base molecule a ects its electronic properties. This gives versatility for more options and tuneability in terms of developing new molecular electronic devices. This project will focus on the theoretical study of a system composed of a graphene quantum dot (Circum-1-coronene) and their interaction with the metal oxide clusters of TiO2 and ZnO. The calculation of thermodynamical, optical, electronic properties with density functional theory (DFT) for the graphene quantum dot (GQD) and their interaction with metal oxide clusters. The achievement of this goal was done implementing a systematic modi cation to the graphene base molecule, optimizing and characterizing the thermodynamical interaction with the titanium dioxide and zinc oxide clusters of sizes from 1 unit to 5 and 6 units, respectively. We also analyzed optical properties through the calculation of excited state to obtain UV-vis absorption spectra. Lastly to calculate their e ect on the electron transport molecular junction, MMM was designed. The metal electrodes were gold nanowires and the base molecule was the GQD (Circum-1-Coronene). In the arrangement of the molecular junction, the main plane of the GQD is parallel to the

ow of the current and its modi cation is with the adsorption of the TiO2 and ZnO clusters. With the previous methodology, we found free Gibbs energy of adsorption in the order of 􀀀180:8kJmol􀀀1 and 􀀀151kJmol􀀀1 for Cir1cor􀀀(ZnO)6 and Cir1cor.

(TiO2)5 hybrid systems. Also we generate a set of molecular characteristics that may permit the development of a optical sensor capable of checking if the metal oxide clusters are adsorbed on the GQD. Lastly we nd the result to modulate the conductance of the GQD between a range of 25% to 75% of the original isolated conductance. This calculations may help the research and development for the design of future molecular electronic devices.