Synthesis and zero-dimensional structure of a new lead-free organic–inorganic[(C 2 H 5 ) 4 N] 3 Bi 2 I 9 compound: a promising material for optoelectronic devices

cations. The organic and inorganic components are connected through C-H⋯I hydrogen bonds. These interactions lead to the formation of a stable three-dimensional supramolecular network. Hirshfeld surface analysis shows that H⋯I/I⋯H and H⋯H interactions dominate the intermolecular contacts. Weak I⋯I interactions also contribute to the structural cohesion. Thermal analyses (DSC and TGA/DTA) reveal a reversible phase transition in the temperature range of 331-340 K. No weight loss is observed during this transition. This behavior may affect the electrical properties of the compound and enhance its potential for temperature-dependent electronic applications. Nyquist plots display a single semicircular arc, which is characteristic of non-Debye relaxation. The AC conductivity follows Jonscher's universal power law. These results indicate thermally activated charge transport governed by the correlated barrier hopping (CBH) model.