Fabrication of bendable and narrow bandgap Cu(In,Ga)(S,Se)2 for tandem photovoltaics

• Published in: Communications materials 2025-01, Vol.6 (1), p.2-8, Article 2
• Main Authors: Hamtaei, Sarallah, Debot, Alice, Scaffidi, Romain, Brammertz, Guy, Cariou, Estelle, Garner, Sean M., Aguirre, Aranzazu, Poortmans, Jef, Dale, Phillip J., Vermang, Bart
• Format: Article
• Language: English
• Subjects: 639/301/299/946; 639/4077/4072/4062; Absorbers; Biocompatibility; Biomedical materials; Chemistry and Materials Science; Energy gap; Form factors; Materials Science; Minority carriers; Near infrared radiation; Open circuit voltage; Photovoltaic cells; Solar cells; Thin films; Toxic wastes; Toxicity
• ISSN: 2662-4443; 2662-4443
• DOI: 10.1038/s43246-024-00706-x

Cu(In,Ga)(S,Se) 2 absorbers with a bandgap in the near-infrared region are ideal candidates for a bottom cell in multi-junction solar cell architectures. In flexible and lightweight form factors, such devices could help power many applications through integrated solar cells. Here, we show the use of a two-step method to synthesize Cu(In,Ga)(S,Se) 2 , with a bandgap between 1.00 and 1.13 eV, on bendable ultra-thin glass, with minority carrier lifetimes approaching 100 ns, in a homogenous and repeatable fashion. We also report on conventional and alternative device fabrication methods with very low waste and toxicity footprints. Champion solar cells are fabricated based on absorbers with a graded bandgap between 1.05 and 1.1 eV, and an open circuit voltage approaching 600 mV. Our results show a way for scalable fabrication of all thin-film, flexible tandem solar cells, by means of industrially relevant processing steps in a low cost and sustainable fashion. Moving towards flexible photovoltaics is attractive in self-powered wearable opto-electronics and biomedical applications. Here, a simple fabrication approach for growing Cu(In,Ga)(S,Se)>sub /sub