Formation of 1D "Perovskitoid" (API)PbBr Instead of Layered <110> Oriented 2D-Perovskite (API)PbBr Under Different Dissolution Temperatures.

The corrugated <110> oriented layered metal halide perovskites (MHP) are gaining increased attention for a variety of properties including intrinsic white light emission. One prototypical candidate is 1-(3-aminopropyl)imidazole lead bromide, which was reported to crystallize as the <110> oriented perovskite (API)PbBr [API = 1-(3-aminopropyl)imidazole]. This work shows that under similar reaction conditions, the same components can instead form (API)PbBr, which has a "perovskitoid" structure. (API)PbBr exhibits a reversible phase transition between 60 and -20 °C from a polar space group 2 to a centrosymmetric space group . The structures and properties of both phases have been characterized by single-crystal and powder X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (ssNMR) accompanied by variable-temperature optical absorption and photoluminescence. In addition, a thermal decomposition of (API)PbBr into (API)PbBr has been observed between 250 and 300 °C.