Issue 6, 2019

Negative photoresponse in ZnO–PEDOT:PSS nanocomposites and photogating effects

Abstract

We report negative photoresponse or increase of resistance in nanocomposites of n-type ZnO nanoparticles dispersed in a p-type polymer (PEDOT:PSS) under UV and visible light excitation, contrary to that of planar heterojunctions of the constituents. The underlying mechanism of charge transport, specifically negative photoresponse, is explored using spectroscopic and opto-electrical characterisation. Systemic variability in conductance, photoresponse sensitivity and rate with fractional nanoparticle loading in the nanocomposite is demonstrated. Here, photogenerated electrons in ZnO nanoparticles, trapped by the unbiased interfacial barrier, are understood to localize holes in the PEDOT:PSS conduction channel thereby increasing the overall nanocomposite resistance. Reversibility of the negative PR although with a slow decay rate bears testament to the proposed photogating mechanism as opposed to photocatalytic activity. Replacement of the p-type polymer with an electron transport matrix turns the negative photoresponse positive accentuating the role of the interfacial barrier in tuning the optoelectronic response of the composites. These hybrid materials and their unusual behaviour provide alternative strategies for building devices with novel photogating effects, exploiting the properties of their nanostructured forms.

Graphical abstract: Negative photoresponse in ZnO–PEDOT:PSS nanocomposites and photogating effects

Supplementary files

Article information

Article type
Paper
Submitted
23 Feb 2019
Accepted
03 May 2019
First published
06 May 2019
This article is Open Access
Creative Commons BY-NC license

Nanoscale Adv., 2019,1, 2435-2443

Negative photoresponse in ZnO–PEDOT:PSS nanocomposites and photogating effects

H. G, S. Vempati, K. N. Prajapati, K. Bandopadhyay, V. Kalathingal and J. Mitra, Nanoscale Adv., 2019, 1, 2435 DOI: 10.1039/C9NA00116F

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