Computational Analysis of the Optical and Charge Transport Properties of Ultrasonic Spray Pyrolysis-Grown Zinc Oxide/Graphene Hybrid Structures

Abstract

We demonstrate a systematic computational analysis of the measured optical and charge transport properties of the spray pyrolysis-grown ZnO nanostructures, i.e. nanosphere clusters (NSCs), nanorods (NRs) and nanowires (NWs) for the first time. The calculated absorbance spectra based on the time-dependent density functional theory (TD-DFT) shows very close similarity with the measured behaviours under UV light. The atomic models and energy level diagrams for the grown nanostructures were developed and discussed to explain the structural defects and band gap. The induced stresses in the lattices of ZnO NSCs that formed during the pyrolysis process seem to cause the narrowing of the gap between the energy levels. ZnO NWs and NRs show homogeneous distribution of the LUMO and HOMO orbitals all over the entire heterostructure. Such distribution contributes to the reduction of the band gap down to 2.8 eV, which has been confirmed to be in a good agreement with the experimental results. ZnO NWs and NRs exhibited better emission behaviours under the UV excitation as compared to ZnO NSCs and thin film as their visible range emissions are strongly quenched. Based on the electrochemical impedance measurement, the electrical models and electrostatic potential maps were developed to calculate the electron lifetime and to explain the mobility or diffusion behaviours in the grown nanostructure, respectively.

Transport Properties and Sensing Responses of Platinum Nanoparticles/Graphene Structure Fabricated by Thermal Annealing Process

“…The measured sensing characteristics suggest that the synthesized Pt NPs are able to act as the effective cracking catalyst to allow the absorption of H 2 even though the deposited thickness of 16 nm is relatively thick and the H 2 concentration of 0.5% is low. The obtained results are comparable with the other reported works (Ali & Hashim 2016;Phan & Chung 2014).…”

“…In this work, the annealing is performed under N 2 at annealing temperature beyond 500°C which tends to decompose the graphene matrix, where certain part of sp 2 bonds in graphene start to break resulting to the graphitic formation (Phan & Chung 2014). Such decomposition of graphene matrix will deteriorate the charge transport property to certain extent and hence the conductivity of the entire structure will be reduced (Ali & Hashim 2016;Phan & Chung 2014).…”

A Short Review of the Architecture and Computational Analysis in the Design of Graphene Based Bioelectronic Devices

“…As can be seen in the figure, the electrostatic potential depends strongly on structure, as has been mentioned in our work. (75)(76)(77) We found that the transport time for electrons differs by about 10 orders of magnitude between nanorods and nanosphere clusters. (75) The use of graphene as an interface layer in the ZnO-decorated sensor is the main reason behind the sensitivity of the transport properties to the volumetric changes in the structures.…”

“…(75)(76)(77) We found that the transport time for electrons differs by about 10 orders of magnitude between nanorods and nanosphere clusters. (75) The use of graphene as an interface layer in the ZnO-decorated sensor is the main reason behind the sensitivity of the transport properties to the volumetric changes in the structures. Detailed information based on X-ray absorption measurements (XAS), from the bulk and the surface on the degree of carbon sp 3 /sp 2 hybridization and oxygen functional groups in two different C thin films is presented in the following.…”

“…Such a combination was reported as a glucose biosensor. (74,75) The ZnO branch is not symmetric, which resulted in an asymmetric electrostatic field around the atoms. Consequently, the diffusion of the glucose into the interface was direction dependent.…”