Growth of a Pure and Single Phase Iron Sulfide (Pyrite) Thin Film by Electrochemical Deposition for Photovoltaic Applications

Abstract

Single phase iron pyrite (FeS 2) 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 FeSO 4 •7H 2 O as an iron source, and Na 2 S 2 O 3 •5H 2 O 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 FeS 2 pyrite thin films.

Iron Pyrite in Photovoltaics: A Review on Recent Trends and Challenges

“…Postsulfurization was then carried out to convert iron sulfide into iron disulfide. The diffraction pattern was a perfect match to phase-pure pyrite with a rough morphology and irregular shapes as studied by SEM shown in Figure b …”

“…(b) SEM micrograph of the FeS 2 thin film. Reproduced with permission from ref . Copyright [2019] Scientific Research Publishing Inc.…”

“…The diffraction pattern was a perfect match to phase-pure pyrite with a rough morphology and irregular shapes as studied by SEM shown in Figure 13b. 106 More recently, Zebarjad et al also produced iron pyrite thin films through electrochemical deposition in a three-electrode system comprising fluorine-coated tin oxide (FTO) glass, platinum, and a saturated calomel electrode. FeCl 3 •6H 2 O and NS 2 S 2 O 3 •5H 2 O were used as the iron and sulfur sources, respectively.…”

The Effect of Deposition Time and Sulfurization Temperature on The Optical and Structural Properties of Iron Sulfide Thin Films Deposited from Acidic Chemical Baths

“…It also removes defects and other phases of FeS2 to obtain pure pyrite. In this work, the sulfurization process was carried out using the technique described by Botchway et al (2019) in Figure 3. A borosilicate tube furnace with two heating zones was flushed with argon for 10 minutes to get rid of any oxygen.…”

Iron Oxide and Iron Sulfide Films Prepared for Dye-Sensitized Solar Cells

“…These conductive metallic phases destroy the semi-conductive properties of FeS 2 , reducing the quality of the resultant material. The conversion of the FeS phase to FeS 2 is possible by chemical methods [5], but attention must be paid to avoid FeS residuals. The Fe-O-S phase diagram (see Figure 1, top left [6]) shows that pyrite synthesis in the absence of oxygen crosses the FeS phase.…”