Title: Study on the origin of the open-circuit photovoltage enhancement in TiO₂ nanotube-based dye sensitised solar cells

Authors: Shan Pang; Zhenwei Zhao; Zuliang Du

Addresses: Key Lab for Special Functional Materials of Ministry of Education, Kaifeng, 475004, China ' Key Lab for Special Functional Materials of Ministry of Education, Kaifeng, 475004, China ' Key Lab for Special Functional Materials of Ministry of Education, Kaifeng, 475004, China

Abstract: A larger value (0.86 V) of open-circuit photovoltage (V_oc) of the TiO₂ nanotube (NT)-based dye sensitised solar cells (DSSCs) than that of DSSCs constructed from TiO₂ nanoparticles (NPs) has been observed. Work function of TiO₂ NTs is about 0.3 eV less than that of TiO₂ NPs, which indicates that the conduction band in TiO₂ NTs may has a more negative shift in comparison with that of TiO₂ NPs after TiO₂ contacts with oxidative electrolyte. This may be one origin of V_oc enhancement. Moreover, comparative analyses on surface photovoltage and transient photovoltage of TiO₂ NPs and NTs show that the larger built-in field in the interface between TiO₂ NTs and Ti foil can further improve charge separation and transport in the TiO₂ NT film, which will result in recombination decrement and charge lifetime increment. This may be the other origin of V_oc enhancement.

Keywords: TiO2 nanotube arrays; titanium dioxide; titania; open-circuit photovoltage; work function; surface photovoltage; SPV; nanotubes; nanotechnology; sensitised solar cells; DSSC; recombination decrement; charge lifetime.

DOI: 10.1504/IJNM.2016.079230

International Journal of Nanomanufacturing, 2016 Vol.12 No.3/4, pp.353 - 362

Received: 07 Aug 2015
Accepted: 04 Jan 2016
Published online: 23 Sep 2016 *

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