Chemical spray pyrolysis synthesis of covellite copper sulphide (CuS) thin films for economical counter electrode for DSSCs

• Published in: Journal of materials science. Materials in electronics 2018-03, Vol.29 (6), p.4940-4947
• Main Authors: Diwate, Kiran, Rondia, Sachin, Mayabadi, Azam, Rokade, Avinash, Waykar, Ravindra, Borate, Haribhau, Funde, Adinath, Shinde, Manish, Rajedra Prasad, M. B., Pathan, Habib, Jadkar, Sandesh
• Format: Article
• Language: English
• Subjects: Carrier mobility; Characterization and Evaluation of Materials; Chemical synthesis; Chemistry and Materials Science; Copper; Copper sulfides; Covellite; Electrical properties; Electrochemical impedance spectroscopy; Electrodes; Electron microscopy; Emission analysis; Energy conversion efficiency; Field emission microscopy; Four point probe method; Materials Science; Optical and Electronic Materials; Optical properties; Quantum dots; Spectrum analysis; Spray pyrolysis; Substrates; Thin films
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-017-8453-6

Thin films of covellite copper sulphide (CuS) were deposited on FTO substrates using chemical spray pyrolysis technique. Influence of Cu-to-S molar ratio on structural, surface morphological, optical and electrical properties were systematically investigated using variety of characterization techniques. Formation of covellite CuS films was confirmed by low angle-XRD and Raman spectroscopy. The field emission scanning electron microscopy analysis revealed the formation of faceted CuS particles without secondary growth. Optical studies exhibited decrease in optical band gap (from 2.21 to 1.69 eV) with increase in Cu-to-S molar ratio. Electrical properties were investigated using Van der Pauw four point probe method and Hall measurements revealed that as-synthesized CuS films have low sheet resistance (1.47–2.45 Ω/□), high carrier mobility (8.90–54.89 cm 2 /Vs) and high sheet concentration (10 16 –10 18 /cm 2 ). The CuS films deposited at optimized Cu-to-S molar ratio (1:2.5) were then further studied for electrochemical impedance spectroscopy and photovoltaic characteristics. A quantum-dot sensitized solar cell incorporating optimized CuS film as counter electrode showed power conversion efficiency of ~ 1.05% with V oc ~ 0.46 V, I sc ~ 1.01 mA/cm 2 and fill factor ~ 0.34%. Although the cell is not fully optimized and better results can be anticipated.