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Optoelectronics properties of tungsten oxide nanoparticle networks deposited by flame spray pyrolysis

Published online by Cambridge University Press:  26 June 2018

Domenico Caputo*
Affiliation:
Department of Information Engineering, Electronics and Telecommunications, University of Rome Sapienza, Rome, Italy.
Shaul Ajò
Affiliation:
Department of Information Engineering, Electronics and Telecommunications, University of Rome Sapienza, Rome, Italy.
Giampiero de Cesare
Affiliation:
Department of Information Engineering, Electronics and Telecommunications, University of Rome Sapienza, Rome, Italy.
Alessio Buzzin
Affiliation:
Department of Information Engineering, Electronics and Telecommunications, University of Rome Sapienza, Rome, Italy.
Renheng Bo
Affiliation:
Nanotechnology Research Laboratory, Research School of Engineering, Australian National University, Canberra, ACT, Australia.
Antonio Tricoli
Affiliation:
Nanotechnology Research Laboratory, Research School of Engineering, Australian National University, Canberra, ACT, Australia.
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Abstract

In this work, we present the optoelectronic characterization of pure tungsten oxide nanoparticle networks synthesized and self-assembled by flame spray pyrolysis. Current-voltage measurements performed in dark conditions indicate the presence of trapping and de-trapping phenomena from defects inside the energy gap. The presence of defects is confirmed by the time evolution of the photocurrent, measured under monochromatic radiation at 420 nm. After illuminating the WO3 films with light, the current increases exponentially with a time constant independent on the applied voltage. This behavior is ascribed to the presence of defects lying at 1.1 eV below the conduction band of WO3 (bandgap of ca. 2.9 eV). When the illumination is terminated, the photocurrent shows an exponential decrease, once again independently on the applied voltage. The defect level corresponding to this relaxation process corresponds to 0.92eV below the conduction band.

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Articles
Copyright
Copyright © Materials Research Society 2018 

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