Title: Effect of trap depth and interfacial energy barrier on charge transport in inverted organic solar cells employing nanostructured ZnO as electron buffer layer

Authors: Naveen Kumar Elumalai; Chellappan Vijila; Rajan Jose; Zhang Jie; Seeram Ramakrishna

Addresses: National University of Singapore, 117576, Singapore; Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 3 Research Link, 117602, Singapore ' Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 3 Research Link, 117602, Singapore ' Universiti Malaysia Pahang, 26300 Pahang, Malaysia ' Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 3 Research Link, 117602, Singapore ' National University of Singapore, 117576, Singapore

Abstract: Inverted organic solar cells with device structure ITO/ZnO/poly (3-hexylthiophene) (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PCBM)/MoO3/Ag were fabricated employing low temperature solution processed ZnO as electron selective layer. Devices with varying film thickness of ZnO interlayer were investigated. The optimum film thickness was determined from photovoltaic parameters obtained from current-voltage measurements. Furthermore, the distribution of localised energy states or trap depth and the ohmicity of the contacts in the optimised device were evaluated, using the temperature and illumination intensity dependent study. The results demonstrate the effect of trap depth distribution on the charge transport, device performance, and stability of the contacts.

Keywords: zinc oxide; ZnO; trap depth; temperature dependence; electron selective layer; solution processed; charge transport; nanoelectronics; nanotechnology; inverted solar cells; organic solar cells; nanostructures; optimum film thickness; photovoltaic parameters; interfacial energy barrier.

DOI: 10.1504/IJNT.2014.059833

International Journal of Nanotechnology, 2014 Vol.11 No.1/2/3/4, pp.322 - 332

Available online: 14 Mar 2014 *

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