12.95% Efficient Cu(In,Ga)Se₂ Solar Cells by Single-Step Atmospheric Selenization, Scaled to Monolithically Integrated Modules

High-quality Cu(In,Ga)Se2 (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 cm2 (average total area, 16 cm2—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 cm2 area is systematically mapped to further design and scale up the process for developing monolithically integrated prototype modules on a 5 × 5 cm2 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 open-circuit 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.