Structural phase transition drives outright photoluminescence quenching and dielectric duple bistable switching

Abstract

Organic–inorganic metal halides (OIMHs) possessing switchable optical and electrical properties hold significant promise for applications in multifunctional sensors, switching devices, and information storage. However, the challenge lies in achieving effective regulation of optical/electric responses through structural design strategies, and materials with structural phase transition coupling photoluminescence (PL) quenching are also relatively rare. Here, by employing halogen engineering to modify the parent compound (TEMA)PbBr₃ (TEMA = triethylmethylammonium), we successfully obtained two derivatives (TECA)PbBr₃ and (TEBA)PbBr₃ (TECA = triethylchloromethylammonium and TEBA = triethylbromomethylammonium). Halogen engineering successfully introduces halogen–halogen interactions between PbBr₃ⁿ⁻ inorganic frameworks and organic cations, which increases the stretching distortion of the PbBr₆ octahedral framework of (TECA)PbBr₃ and (TEBA)PbBr₃, accompanied by prominent orange-red broadband emission behavior in (TECA)PbBr₃ and (TEBA)PbBr₃. Meanwhile, the phase transition temperatures (T_p) of (TECA)PbBr₃ and (TEBA)PbBr₃ have also been significantly increased compared to (TEMA)PbBr₃, and two derivatives demonstrated switchable dielectric responses. Impressively, the reversible structural phase transition of (TECA)PbBr₃ and (TEBA)PbBr₃ dominates the outright PL quenching behavior, while still maintaining high PL emission intensity below the T_p. This represents a rare and extraordinary phenomenon in the realm of bistable responsive materials. This work provides a feasible strategy for designing and modulating photoluminescent phase transition materials and deepens understanding of the structural–performance relationship.