0‐D and 1‐D Perovskite‐like Hybrid Bismuth(III) Iodides

Abstract

Low‐dimensional hybrid bismuth halide perovskites have recently emerged as a class of non‐toxic alternative to lead perovskites with promising optoelectronic properties. Here, we report three hybrid bismuth(III)‐iodides: 0‐D (H2DAC)2Bi2I10·6H2O (H2DAC_Bi_I), 0‐D (H2DAF)4Bi2I10·2I3·2I·6H2O (H2DAF_Bi_I), and 1‐D (H2DAP)BiI5 (H2DAP_Bi_I) (where H2DAC = trans‐1,4‐diammoniumcyclohexane; H2DAF = 2,7‐diammoniumfluorene and H2DAP = 1,5‐diammoniumpentane). Their synthesis, single‐crystal X‐ray structures, and photophysical properties are reported. The first two compounds comprise edge‐sharing [Bi2I10]4‐ dimers, while the last compound has cis‐corner‐sharing 1‐D chains of [BiI6]3‐ octahedra. Intercalation of triiodide (I3‐) and iodide (I‐) ions enhance electronic coupling between the [Bi2I10]4‐ of H2DAF_Bi_I, leading to enhanced optical absorption when compared to H2DAC_Bi_I which lacks such intercalants. Furthermore, calorimetric and variable temperature X‐ray diffraction measurements suggest a centrosymmetric to non‐centrosymmetric phase transition (monoclinic P212121 ↔ orthorhombic Pnma) of H2DAP_Bi_I at 448 K (in heating step) and 443 K (in cooling step).