Realizing efficient emission and triple‐mode photoluminescence switching in air‐stable tin(IV)‐based metal halides via antimony doping and rational structural modulation

Recently, many lead‐free metal halides with diverse structures and highly efficient emission have been reported. However, their poor stability and single‐mode emission color severely limit their applications. Herein, three homologous Sb 3+ ‐doped zero‐dimensional (0D) air‐stable Sn(IV)‐based metal halides with different crystal structures were developed by inserting a single organic ligand into SnCl 4 lattice, which brings different optical properties. Under photoexcitation, (C 25 H 22 P)SnCl 5 @Sb·CH 4 O ( Sb 3+ −1 ) does not emit light, (C 25 H 22 P) 2 SnCl 6 @Sb‐α ( Sb 3+ −2α ) shines bright yellow emission with a photoluminescence quantum yield (PLQY) of 92%, and (C 25 H 22 P) 2 SnCl 6 @Sb‐β ( Sb 3+ −2β ) exhibits intense red emission with a PLQY of 78%. The above three compounds show quite different optical properties should be due to their different crystal structures and the lattice distortions. Particularly, Sb 3+ −1 can be successfully converted into Sb 3+ −2α under the treatment of C 25 H 22 PCl solution, accompanied by a transition from nonemission to efficient yellow emission, serving as a “turn‐on” photoluminescence (PL) switching. Parallelly, a reversible structure conversion between Sb 3+ −2α and Sb 3+ −2β was witnessed after dichloromethane or volatilization treatment, accompanied by yellow and red emission switching. Thereby, a triple‐mode tunable PL switching of off–on I –on II can be constructed in Sb 3+ ‐doped Sn(IV)‐based compounds. Finally, we demonstrated the as‐synthesized compounds in fluorescent anticounterfeiting, information encryption, and optical logic gates.