Journal ArticleSr(Ag _1−<i>x</i> Li _<i>x</i> ) ₂ Se ₂ and [Sr ₃ Se ₂ ][(Ag _1−<i>x</i> Li _<i>x</i> ) ₂ Se ₂ ] Tunable Direct Band Gap SemiconductorsZhou, Xiuquan; Wilfong, Brandon; Chen, Xinglong; Laing, Craig; Pandey, Indra R.; Chen, Ying‐Pin; Chen, Yu‐Sheng; Chung, Duck‐Young; Kanatzidis, Mercouri G.<title>Abstract</title> <p>Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid‐state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two‐dimensional Sr(Ag_{1−<italic>x</italic>}Li_{<italic>x</italic>})₂Se₂layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag_{1−<italic>x</italic>}Li_{<italic>x</italic>})₂Se₂with<italic>x</italic>up to 0.45. In addition, a new type of intergrowth compound [Sr₃Se₂][(Ag_{1−<italic>x</italic>}Li_{<italic>x</italic>})₂Se₂] was synthesized upon further reaction of Sr(Ag_{1−<italic>x</italic>}Li_{<italic>x</italic>})₂Se₂with SrSe. Both Sr(Ag_{1−<italic>x</italic>}Li_{<italic>x</italic>})₂Se₂and [Sr₃Se₂][(Ag_{1−<italic>x</italic>}Li_{<italic>x</italic>})₂Se₂] exhibit a direct band gap, which increases with increasing Li substitution (<italic>x</italic>). Therefore, the band gap of Sr(Ag_{1−<italic>x</italic>}Li_{<italic>x</italic>})₂Se₂can be precisely tuned via fine‐tuning<italic>x</italic>that is controlled by only the flux ratio and temperature.</p>John Wiley & Sons, Ltd2023-03-2710491770Angewandte Chemie International Edition6214e2023011911433-7851https://doi.org/10.1002/anie.2023011911834750National Science Foundation