Tin 4 chloride pentahydrate sncl4 5h2o

ZnO NW and
NF thin films have been prepared via chemical bath deposition (CBD)
as described in our earlier reports.^{34 (link),45 (link)} ZTO and CIGS/InS
layers have been deposited on the ZnO nanostructured thin films via
ultrasonic spray pyrolysis.^{46 (link)−49 (link)} For the ZTO layer, 25 mM zinc acetate dihydrate (Zn(CH₃COO)₂·2H₂O, Sigma-Aldrich, 99%)
and 75 mM tin(IV) chloride pentahydrate (SnCl₄·5H₂O, Sigma-Aldrich, 98%) were dissolved in methanol–deionized
water (v/v = 3:1) and sprayed on the ZnO thin films with a 20 pass
number, 48 kHz at 200 °C. The ZTO layer was then annealed at
550 °C for 2 h for complete transformation of the ZnSn(OH)₆ phase to ZTO. CIGS and In₂S₃ layers
were deposited as described in the literature.^{44 (link)} The thin-film electrode preparation route is schematically
summarized in Figure 1.

Pyrrole monomer (C₄H₅N) (99%, Sigma-Aldrich, Bengaluru, India), Ferric chloride (FeCl₃) (97%, Sigma-Aldrich, Bengaluru, India), Tin (IV) chloride pentahydrate (SnCl₄·5H₂O) (98%, Sigma-Aldrich, Bengaluru, India), Hydrazine hydrate (N₂H₄·H₂O) (98%, Merck Chemicals, Bengaluru, India), graphite powder (99.99%, Sigma-Aldrich, Bengaluru, India), and Polyvinylidene difluoride (PVDF) (99%, Sigma-Aldrich, Bengaluru, India) were used without further purification. Potassium Hydroxide (KOH), N-Methyl-2-pyrrolidone (NMP), Hydrogen peroxide (H₂O₂), and activated carbon were purchased from Merck Chemicals, Bengaluru, India. Nitric acid (HNO₃) and Sulphuric acid (H₂SO₄) were purchased from Merck Chemicals, Bengaluru, India (99.99%), in addition to Polyvinyl Alcohol (PVA) being obtained (99%, Sigma-Aldrich, Bengaluru, India). All the reagents were used as received without any purification. Ultra-pure water was used throughout the experiments, which was attained from a Milli-Q system from Millipore (Milford, MA, USA).

Nanocrystalline SnO₂ was synthesized by chemical precipitation method [25 (link)]. Tin (IV) chloride pentahydrate SnCl₄·5H₂O (15.00 g, 98%, Sigma-Aldrich, St. Louis, MO, USA) was dissolved in deionized water (150 mL). Aqueous ammonia (25%) was added dropwise to the resulting solution with vigorous stirring with a magnetic stirrer until pH = 7. The synthesis was carried out at room temperature. The gel-like precipitate was separated by centrifugation (3500 rpm, 3 min.), washed several times with deionized water and then with 0.01 M solution of NH₄NO₃ (99%, Sigma-Aldrich) until complete removal of chloride anions (AgNO₃ test). The resulting precipitate of the α-stannic acid gel was dried at 100 °C for 24 h, then the vitreous product was ground in an agate mortar and annealed in air at 300 °C for 24 h.
To obtain nanocrystalline In₂O₃, aqueous ammonia solution (25%) was added dropwise to the stirred solution of In(NO₃)₃·4.5Н₂O (5.00 g in 50 mL deionized water) until pH = 7 at room temperature. The resulting white gel of indium (III) hydroxide was separated by centrifugation and repeatedly washed several times with deionized water until the beginning of the peptization process. The obtained precipitate was dried at 100 °C for 24 h, then was ground in an agate mortar and annealed in air at 300 °C for 24 h.