In4 S4

In₄S₄ is an indium sulfide semiconductor compound belonging to the III-VI semiconductor family, characterized by a mixed-valence indium structure. This material is primarily investigated in research contexts for optoelectronic and photovoltaic applications, where its band gap and electronic properties show promise for thin-film solar cells, infrared detectors, and light-emitting devices. Relative to conventional alternatives like CdTe or CIGS solar absorbers, In₄S₄ offers potential advantages in terms of earth abundance and reduced toxicity concerns, though it remains less mature for industrial-scale production than established semiconductors.