Aluminium doped zinc oxide is prepared using spark plasma sintering. The process leads to a tailored optical band gap extending into the visible region with increasing aluminium concentration. Microstructural, optical, and electrical characterization were carried out to investigate the effect of the sintering process and aluminium concentration on the grain size, band gap, and electrical conductivity. The delocalization of impurity energy states created during sintering, causes band gap narrowing and leads to an improved conductivity. The impurity states are primarily oxygen vacancies and zinc interstitials. Spark plasma sintering offers a promising approach to synthesize doped conductive metal oxides with control over the band gap and can be extended to a variety of other systems. © 2016 The Royal Society of Chemistry.

P. Swaminathan

Department of Metallurgical and Materials Engineering

Sonia Sharma

Raghavendar Bayikadi

Aluminum

Energy gap

Oxygen vacancies

Spark plasma sintering

Zinc

Zinc oxide

ALUMINIUM CONCENTRATION

Band gap narrowing

Doped zinc oxides

Electrical characterization

Electrical conductivity

IMPURITY ENERGY STATE

Sintering process

Zinc interstitials

Sintering

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

RSC Advances

In this work, we describe the preparation of a zinc oxide-ethylene glycol nanoparticle ink and the parameters that control the printing using a custom-built direct writer system. The ink (nanoparticle dispersion) was prepared using a two-step wet synthesis method, without using any surfactant. Its viscosity was found to be in the suitable range for printing and straight lines were printed on cleaned glass substrates. The influence of various printing parameters, such as total dispersed volume, number of printed layers, substrate temperature, drying temperature and time, and particle loading, on the morphology of the printed patterns was investigated. In-situ and post-printing drying of the printed pattern, at the same temperature, produced different morphologies, which can be attributed to the direction of heat transfer and solvent removal. Optimization of these printing parameters enabled us to obtain a continuous printed pattern with uniform morphology using a direct writing system, which can be extended to a variety of nanoparticle based inks. © 2018 IOP Publishing Ltd.

Flexible and Printed Electronics

Formulation and optimization of a zinc oxide nanoparticle ink for printed electronics applications

Developing printed optoelectronic devices based on metal oxide inks requires synthesizing stable suspensions of the desired materials. In this work, pure and manganese doped zinc oxide inks were synthesized by a top-down wet milling route and the role of solvent in ink stabilization and printing was analyzed. Fluid properties of the as-prepared inks were measured and used for studying jettability criteria for inkjet printing. Among the various solvents evaluated, ethylene glycol produced stable oxide inks and satisfied the jetting conditions. The inks were evaluated using a commercial drop-on-demand piezoelectric inkjet printer. The morphology of the patterns printed on glass substrates, for various ink volumes, was investigated and was found to be continuous and showed good optical transmittance. We also investigated the particle segregation in these inks using a custom built direct writing system. This top-down approach, by separating the material development and ink synthesis, can be extended to a variety of metal oxide based inks. © 2017 The Royal Society of Chemistry.

Fulltext

Top-down synthesis of zinc oxide based inks for inkjet printing

Manganese-doped zinc oxide powders were synthesized by solid state reaction of the respective oxides. The high-temperature conditions were chosen such that multiple valence states of manganese were doped in the host zinc oxide lattice. Structural characterization was carried out to confirm the doping and to find the maximum amount of manganese that can be incorporated. Diffuse reflectance spectroscopy was used to measure the optical band gap of the doped sample and the lowering with respect to pure ZnO was attributed to the presence of higher oxidation states of manganese. The presence of these oxidation states was confirmed using x-ray photoelectron spectroscopy. The study shows that a solid state reaction is a viable route for synthesizing doped metal oxides with desired optical properties. © 2015, The Minerals, Metals &amp; Materials Society.

Journal of Electronic Materials

Reduction in the Band Gap of Manganese-Doped Zinc Oxide: Role of the Oxidation State

ECS Transactions

Role of Zn-Interstitial Defect in the Ultraviolet Emission from ZnO

International Atomic Energy Agency (IAEA)

Optics and Lasers in Engineering

Enhanced electrical and optical properties of room temperature deposited Aluminium doped Zinc Oxide (AZO) thin films by excimer laser annealing

Scientific Reports

Dopant morphology as the factor limiting graphene conductivity

Spark plasma sintering route to synthesize aluminium doped zinc oxide

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