A Hybrid Organic‐Inorganic Bismuth Iodine Material Showing High Phase Transition Point and Low Bandgap

Abstract

AbstractRecently, hybrid organic‐inorganic lead halide materials have attracted great attention for their applications in the fields of light‐emitting diodes, photovoltaics, photodetector. However, these hybrid materials usually suffer from environmental and human health issues because of the toxic lead moieties. Herein, we report a novel lead‐free bismuth iodide phase transition material, [NH3(CH2)7NH3][BiI5] (1), which undergoes a reversible phase transition at high temperature 351.7 K and exhibits a step fashion dielectric anomaly. The structural phase transition of 1 is mainly originated from the order‐disorder transition of the 1,7‐heptanediamine cations. Besides, the solid‐state UV‐vis spectrum of 1 displays an intense adsorption at around 658 nm; which gives an indirect bandgap of 1.89 eV. Such a small bandgap value is comparable to most of the organic‐inorganic hybrid lead halide type semiconductors. We believe this study will shed light on the exploration of lead‐free organic‐inorganic hybrid metal halide semiconductors toward future device applications.