Cu(In, Ga)(Se, S)2 thin-film technology: Aspects of historical development, current status, and future prospects

Copper indium gallium selenide (CIGS)-based solar cells are a type of thin-film photovoltaic technology used to convert sunlight into electricity. They are one of the most promising thin-film technologies with high efficiency and low-cost potential. CIGS is a direct band gap material with a high absorption coefficient, around 2 µm thickness can absorb most of the light which can reduce the usage of material. CIGS solar cells have a better temperature coefficient, meaning their efficiency decreases less in high-temperature environments compared to other solar technologies. Furthermore, CIGS solar cells also have excellent low-light performance due to their broad absorption spectrum. This allows them to generate electricity even in partially shaded or cloudy conditions, which can be common in urban environments with tall buildings or trees casting shadows. Thus, CIGS solar cells are also a good option to be used for building-integrated PV (BIPV) systems. The latest cell efficiency record was reached in 2023 with 23.6%. Ongoing research aims to increase efficiency, durability, and cost-effectiveness, making the CIGS thin-film technology a mainstream option for solar energy generation.