FeS 2 -quantum-Dot sensitized metal oxide photoelectrodes: Photoelectrochemistry and photoinduced absorption spectroscopy

Abstract

TIO 2, ZnO nanoparticulate(-np), and ZnO-nanorod(-nr) electrodes have been modified with FeS 2 (pyrite) nanoparticles. Quantum size effect is manifested by a blue shift in both absorption and photocurrent action spectra. PIA (photoinduced absorption spectroscopy), a multipurpose tool in the study of dye-sensitized solar cells, is used to study quantum-dot modified metal oxide (MO) nanostructured electrodes. The PIA spectra showed an evidence for long-lived photoinduced charge separation. Time-resolved PIA showed that recombination between electrons and holes occurs on a millisecond timescale. Incident-photon-to-current efficiencies at 400nm are ranged between 13% and 25%. The better solar cell performance of FeS 2 on ZnO-nr over ZnO-np can be ascribed to the faster, unidirectional e-transport channels through the ZnO-nr as well as the longer electron lifetimes. The lower performances of electrodes can be explained by the presence of FeS 2 phases other than the photoactive pyrite phase, as evidenced from XRD study. Copyright © 2011 Idriss Bedja and Anders Hagfeldt.