Aluminum-doped zinc oxide (AZO) is a popular, low-cost, nontoxic material that finds application as a transparent conducting electrode in photonic, sensing, and photovoltaic devices. We report the AZO thin films with a high figure of merit on large-area glass substrates by direct current magnetron sputtering without any intentional substrate heating. Furthermore, a simple thermal post-treatment to improve the transmittance of AZO thin film in the infrared region for its application in low-band-gap devices is presented. High optoelectronic properties are obtained by optimizing oxygen content during the sputtering process. The structural, morphological, optoelectrical, and photoluminescence characterization of cold sputtered AZO films is investigated for its latent applications. AZO thin films with an electrical sheet resistance of 8.8 Ω/□ and a visible light transmittance of 78.5% with thickness uniformity above 95% are achieved on 300 mm × 300 mm glass substrate. The AZO film with optimized process conditions is employed as a transparent electrode to fabricate a copper–indium–gallium–selenide-based thin film solar cell, demonstrating 11.8% power conversion efficiency. The AZO film with optimized sputter conditions was post-treated in ambient conditions with an Al blanket to suppress the resistivity by proper organization of the defects due to Al 3+ consumption and point defects, resulting in improved transparency (85%) in the infrared region with a sheet resistance of 40 Ω/□. This has great potential for developing scalable and low-cost AZO thin films for transparent electrodes in a wide range of the spectrum.

High-quality Cu(In,Ga)Se 2 (CIGS) thin-film solar cells are often prepared by a two-step process, sputtering of Cu-Ga-In precursors followed by multistep selenization, including toxic additional post-deposition treatments and complex instrumentation due to safety apprehensions. We present here a simple and relatively less toxic single-step atmospheric selenization to prepare a high-quality CIGS thin-film absorber. Solar cells made from samples by atmospheric selenization for 15 min at 550 °C without any additional treatment exhibited a power conversion efficiency of up to 12.95% on a device area of 0.48 cm 2 (average total area, 16 cm 2  8.35%, without evaporated grid and antireflective coating). The reproducibility of the results was validated by a multiple set of experiments. Statistical data analysis of the photovoltaic performance parameters of each isolated device on a 16 cm 2 area is systematically mapped to further design and scale up the process for developing monolithically integrated prototype modules on a 5 × 5 cm 2 glass. A serial connection of nine cells (4.5 cm × 0.5 cm) realized by monolithic configuration exhibited a power conversion efficiency of 5% with an opencircuit voltage of 3.85 V from the active area, as demonstrated for real-time application. The present work systematically pronounces conceptualization of lab-scale CIGS thin-film solar devices to a monolithic integration of prototype module utilizing a single-step and simple approach.