TITLE:
Growth of a Pure and Single Phase Iron Sulfide (Pyrite) Thin Film by Electrochemical Deposition for Photovoltaic Applications
AUTHORS:
Emmanuel A. Botchway, Francis K. Ampong, Isaac Nkrumah, Francis K. Boakye, Robert K. Nkum
KEYWORDS:
Iron Pyrite Films, Electrodeposition, Sulfurization, Solar Cell Materials
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.9 No.9,
September
24,
2019
ABSTRACT: Single phase iron pyrite (FeS2)
films have been successfully deposited on ITO-coated glass substrates using a
3-electrode electrochemical system with graphite as the counter electrode and
Ag/AgCl as the reference electrode. In this single-step electrodeposition, the
FeS precursor thin film was directly electrodeposited on the conductive
substrate from the electrolytic bath solution which contained FeSO4.7H2O
as an iron source, and Na2S2O3.5H2O
as a sulfur source. The deposition was carried out potentiostatically at a constant potential of -0.9 V vs. Ag/AgCl at room
temperature. The growth of the iron pyrite phase was achieved by annealing the
as-deposited at 500°C for an hour in an ambient of sulfur to form the pyrite
phase. For
sulfurization, two different techniques, one using the Kipp’s apparatus and a second, which involved heating elemental
sulfur at 200°C, were used for the production of the sulfur gas. X-ray
diffraction analyses of the sulfurized films showed that both sulfurization
techniques appeared
to form the pyrite phase, however, the second method yielded films with maximum crystalline order and
stoichiometry with no discernable impurity peaks. Optical absorption measurements revealed the
existence of a direct transition with an estimated band gap of 1.75 eV. SEM micrograph showed a compact morphology
with a rough surface made up of crystallites of irregular shapes and sizes with
well-defined edges, covering the entire substrate. EDAX analysis of the film was consistent with the
formation of FeS2 pyrite thin films.