"

Cookies ussage consent

Our site saves small pieces of text information (cookies) on your device in order to deliver better content and for statistical purposes. You can disable the usage of cookies by changing the settings of your browser. By browsing our site without changing the browser settings you grant us permission to store that information on your device.

I agree, do not show this message again.

Morphological and optical characterization of transparent thin films obtained at low temperature using ZnO nanoparticles

A. ALEXA1, N. TIGAU2, P. ALEXANDRU1, A. PIMENTEL3, R. BRANQUINHO3, D. SALGUEIRO3, T. CALMEIRO3, R. MARTINS3, E. FORTUNATO3, V. MUSAT1,*

Affiliation

  1. Center of Nanostructures and Functional Materials- CNFM, Faculty of Engineering, "Dunărea de Jos" University of Galati, Galati, Romania
  2. Center of Nanostructures and Functional Materials- CNFM, Faculty of Sciences and Environment, "Dunărea de Jos" University of Galati, Galati, Romania
  3. CENIMAT/I3N, Departamento de Ciencia dos Materiais, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa (UNL), and CEMOP/UNINOVA, Caparica, Portugal

Abstract

Transparent metal oxides thin films are a class of inorganic conductors and semiconductors with significant importance for use in portable electronics, displays, flexible electronics, multi-functional windows and solar cells. Due to the recent development of transparent and flexible electronics, there is a growing interest in depositing metal-oxide thin-film on plastic substrates that can offer flexibility, lighter weight, and potentially lead to cheaper manufacturing by allowing printing and rollto- roll processing. The plastic substrates, however, limit device processing to below 200oC. In this context, the deposition of high-performance semiconductor thin films from dispersions of pre-prepared oxide nanoparticles at temperatures below 200oC represents a potential key route. This paper reports on the preparation of ZnO transparent thin films using solutionprocessed nanoparticles (NPs) precipitated from zinc acetate alcoholic solution with potassium hydroxide. The nanoparticles size distribution, microstructure and crystallinity were measured by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The thin films were deposited by spin-coating onto soda lima glass substrate, using a dispersion of 1wt% ZnO NPs. The morphology of the films annealed at 120 and 180oC, observed by atomic force microscopy and cross-section scanning electron microscopy, shows columnar grains with diameter ranging between 20 and 70 nm, depending on the conditions of depositions. Optical measurements indicated high transparency, between 85 and 94 %, in the visible range, a direct nature of band-to-band transitions and band gap values between 3,22 and 3,32 eV. The refractive index and extinction coefficient have been calculated from optical transmittance and reflectance spectra..

Keywords

ZnO nanoparticles, Transparent thin films, Morphology, Microstructure, Optical properties.

Submitted at: July 20, 2015
Accepted at: Sept. 9, 2015

Citation

A. ALEXA, N. TIGAU, P. ALEXANDRU, A. PIMENTEL, R. BRANQUINHO, D. SALGUEIRO, T. CALMEIRO, R. MARTINS, E. FORTUNATO, V. MUSAT, Morphological and optical characterization of transparent thin films obtained at low temperature using ZnO nanoparticles, Journal of Optoelectronics and Advanced Materials Vol. 17, Iss. 9-10, pp. 1288-1295 (2015)