Layered Arrangement of 1D Wavy Chains in the Lead‐Free Hybrid Perovskite (PyrCO2H)2BiI5: Structural Investigations and Properties

Abstract

AbstractLead free organic‐inorganic hybrid perovskites have attracted increasing attention because of their variety of applications such as photovoltaics or lighting. Here, we reported a new iodobismuthate organic‐inorganic perovskite (PyrCO2H)2BiI5 where PyrCO2H+ is the 4‐carboxy‐1‐methylpyridinium. In the room temperature orthorhombic phase, the one‐dimensional (1D) inorganic framework which consists of cis‐connected corner‐sharing BiI6 octahedra, exhibits a sinusoidal deformation along the chain axis, while a regular chain leading to a sub‐cell is found in the high temperature phase (T>390 K). An original structural feature is the relative position of consecutive 1D chains in planes leading to a layered character of this organic‐inorganic compound. The electrical properties as function frequencies and temperatures have been studied in particular allowing the extraction of Rg and further the calculation of σg=f(T). Interestingly, a change of activation energy is detected at the phase transition temperature (390 K). The higher value of activation energy above 390 K can be attributed to change of the conduction mechanism involving ionic conduction.