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

Abstract

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.

Pulse Selenization in Cu(In,Ga)Se2 Solar Cells: A Promising Approach to Achieve High Efficiency by Electrodeposition

“…Between these two process, post-selenization plays a vital role in the device performance of CIGS solar cells by electrodeposition as well as the vacuum process like sputtering . Until now, one-step selenization is widely used in post-selenization because of its simple operation. − However, this selenization often causes the accumulation of gallium (Ga) near the molybdenum (Mo) layer, forms fine grains at the bottom of the CIGS films, and increases the grain boundary (GB) recombination. Furthermore, large crevices can also be found at the CIGS/Mo interface in one-step selenization, , which is detrimental for the adhesion of CIGS films on the Mo substrate and the effective collection of carriers.…”

Room Temperature Sputtered Aluminum-Doped ZnO Thin Film Transparent Electrode for Application in Solar Cells and for Low-Band-Gap Optoelectronic Devices

“…The AZO thin film with optimized conditions was validated by employing as a top electrode for copper–indium–gallium–selenide (CIGS) thin film solar cell. The device was fabricated in a AZO (900 nm)/ZnO­(40 nm)/CdS (50 nm)/CIGS (1.5 μm)/Mo (800 nm)/SLG (3 mm) substrate configuration; the other experimental details on device fabrication can be found in our previously published work . Further, AZO thin films sputtered with optimized conditions (1% oxygen flux) were post-treated at 500 °C for 30 and 60 min with an Al blanket, and the schematic is presented in Figure S1 of the Supporting Information.…”