Epoxy Catalyzed Sol-Gel Method for Pinhole-Free Pyrite FeS₂ Thin Films

Authors

S. Kment, Academy of Sciences of the Czech Republic and the University of Nebraska-LincolnFollow
H. Kmentova, Academy of Sciences of the Czech Republic and the University of Nebraska-LincolnFollow
A. Sarkar, University of Nebraska-Lincoln
R. J. Soukup, University of Nebraska-Lincoln
N. J. Ianno, University of Nebraska-LincolnFollow
D. Sekora, University of Nebraska-Lincoln
J. Olejnicek, Academy of Sciences of the Czech RepublicFollow
P. Ksirova, Academy of Sciences of the Czech Republic
J. Krysa, Institute of Chemical Technology PragueFollow
Z. Remes, Academy of Sciences of the Czech RepublicFollow
Z. Hubicka, Academy of Sciences of the Czech RepublicFollow

Document Type

Article

Date of this Version

9-15-2014

Citation

Journal of Alloys and Compounds 607 (September 15, 2014), pp. 169–176.

doi: 10.1016/j.jallcom.2014.04.060

Comments

Copyright © 2014 Elsevier B.V. Used by permission.

Abstract

The uniform pinhole-free iron disulfide (FeS₂) pyrite thin films were fabricated. In the first step the FeO(OH)_x xerogel solution was synthetized by means of a novel epoxy catalyzed sol-gel method and next spin-coated onto various substrates to form the thin films. In the second step the xerogel coatings were annealed to yield hematite (α-Fe₂O₃) films, which were transformed into pyrite by chemical sulfurization. Among the main deposition parameters studied were the temperature of xerogel-hematite transformation and the optimal sulfurization temperature and duration. It has been observed that 15 min sulfurization at the temperature of 450°C provided the pyrite films of sufficient quality. The estimated optical band gap of 0.98 eV is very close to the theoretical value of 0.95 eV. Auger electron spectroscopy showed almost ideal stoichiometry of FeS₂. However a trace amount of oxygen (approximately 0.5 at.%) present in the film was still detected. The photoinduced functionality of the films was assessed based on photoelectrochemical experiments. In order to demonstrate the ability of pyrite to photosensitize a large band gap semiconductor, a bilayer system of TiO₂ anatase/FeS₂ pyrite was prepared. The highest photocurrent reached was 45 μA cm^–2 at the light intensity of 10.5 mW cm^–2.