Sr<sub>6</sub>(Li<sub>2</sub>Cd)A<sub>4</sub>S<sub>16</sub> (A = Ge, Sn): How to Go beyond the Band Gap Limitation via Site-Specific Modification
Yu‐Kun Lian, Rui‐An Li, Xin Liu, Li‐Ming Wu, Ling Chen
Abstract
Band gap tuning is at the core of current optical and electronic device applications, the wide-band-gap chalcogenides are especially challenging and highly desired in many fields, such as nonlinear optical materials. On the basis of our in-depth investigation on the complicated cubic AII6(BI2CII)DIV4S16 family, we reveal that the structural complexity causes the band gap tuning to be determined by multiple factors, in which a “bucket effect” is uncovered. Guided by such a bucket effect strategy, we rationally synthesized two new members, Sr6(Li2Cd)A4S16 (A = Ge (1; a = 13.916 Å), Sn (2; a = 14.237 Å), via a site-specific substitution. 1 exhibits the widest band gap (3.8 eV) in this family known to date. Benefiting from their wide band gaps, 1 and 2 exhibit excellent laser irradiation duration capability, with laser-induced damage thresholds (LIDTs) of 55.5 and 44.4 MW/cm2 at a 1.064 μm incident laser, which are 21 and 17 times higher than that of the benchmark AgGaS2 (2.69 MW/cm2). Especially, the LIDT of 1 is the highest known to date among the cubic AII6BI2CIIDIV4S16 family. Our insight into the band gap tuning in a complex system should shed useful light on the future design of functional materials and band gap engineering.