Copper indium gallium selenide (CIGS) is a semiconductor material used primarily in thin-film solar cells. It is composed of four elements: copper, indium, gallium, and selenium. CIGS is known for its high absorption efficiency and flexibility, making it suitable for various applications, including building-integrated photovoltaics. CIGS solar cells can be manufactured on flexible substrates, allowing for lightweight and versatile solar panel designs. They have a high power conversion efficiency compared to other thin-film technologies, which contributes to their growing popularity in renewable energy solutions.