Impact of selenization with NaCl treatment on the physical properties and solar cell performance of crack-free Cu(In,Ga)Se2 microcrystal absorbers

• Published in: RSC advances Vol. 14; no. 7; pp. 4436 - 4447
• Main Authors: Marasamy, Latha, Aruna-Devi Rasu Chettiar, Ravichandran Manisekaran, Evangeline, Linda, Md Ferdous Rahman, M Khalid Hossain, Pérez García, Claudia Elena, Santos-Cruz, José, Subramaniam, Velumani, de Moure Flores, Francisco
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 31.01.2024
• Subjects: Absorbers; Annealing; Blade coating; Copper; Copper indium gallium selenides; Dislocation density; Energy conversion efficiency; Free surfaces; Microcrystals; Microstrain; Parameter modification; Photovoltaic cells; Physical properties; Sodium chloride; Solar cells; Surface treatment; Thin films; Zinc oxide
• ISSN: 2046-2069
• DOI: 10.1039/d3ra05829h

In this study, we developed an ink using hexanethiol and Cu(In,Ga)Se2 microcrystals (CIGSe MCs) to make thin films via doctor blade coating. Besides, crack-free thin films were obtained by optimizing CIGSe MC powder concentration and annealing temperature. Subsequently, single-step selenization was performed with and without sodium chloride (NaCl) surface treatment by carefully tuning the temperature. A crack-free surface with densely packed grains was obtained at 500 °C after NaCl treatment. Moreover, the structural parameters of the thin film (annealed at 350 °C) were significantly modified via selenization with NaCl at 500 °C. For instance, the FWHM of the prominent (112) plane reduced from 1.44° to 0.47°, the dislocation density minimized from 13.10 to 1.40 × 1015 lines per m2, and the microstrain decreased from 4.14 to 1.35 × 10−3. Remarkably, these thin films exhibited a high mobility of 26.7 cm2 V−1 s−1 and a low resistivity of 0.03 Ω cm. As a proof of concept, solar cells were engineered with a device structure of SLG/Mo/CIGSe/CdS/i-ZnO/Al–ZnO/Ag, wherein a power conversion efficiency (PCE) of 5.74% was achieved with exceptional reproducibility. Consequently, the outcomes of this investigation revealed the impact of selenization temperature and NaCl treatment on the physical properties and PCE of hexanethiol-based crack-free CIGSe MC ink-coated absorbers, providing new insights into the groundwork of cost-effective solar cells.