Synthesis, structural and optical study of a new Bi(III)-based hybrid photoluminescent material: (C۵H۵N۴)۴ [Bi۶I۲۲]·۲NO۲ ·۴H۲O

Luminescent organic-inorganic hybrid materials have attracted considerable attention in terms of integrated photo-electronic devices [۱,۲], most of which are focused on the lead-free light emitters [۳-۵]. Recently, Bi-based organic inorganic semiconductors proved their fascinating properties as solid state visible light absorber for solar cells [۶,۷] as well as photoluminescent materials [۸,۹]. In this work, a new quasi-three-dimensional molecular crystal (C۵H۵N۴)۴[Bi۶I۲۲]·۲NO۲·۴H۲O, (C۵H۴N۴ -۱H-۱,۲,۳-Triazolo[۴,۵-b]pyridinium), has been successfully synthesized using slow evaporation method. The synthesized compound abbreviated (HTZP) BiI was characterized by single-crystal X-ray diffraction (SC-XRD), Infrared, UV/Vis/NIR diffuse-reflectance and steady-state photoluminescence spectroscopies. The SC-XRD shows that the synthesized material crystallizes in the triclinic centrosymmetric space group P-۱ with lattice constants of a = ۱۱.۱۸۲۷(۱۲) Å, b = ۱۱.۴۳۹۴(۱۲) Å, c = ۱۷.۳۴۵۳(۱۸) Å, α = ۷۳.۸۶۵(۴)°, β = ۸۹.۰۹۱(۴)° and γ = ۷۴.۷۲۵(۴)°. The asymmetric unit of (HTZP)BiI is made up of [Bi۶I۲۲] clusters, isolated (C۵H۵N۴)+ cations, nitrogen dioxide NO۲ and water molecules. The infrared measurement confirms the presence of the different molecules inside the investigated structure. The UV/Vis/NIR diffuse-reflectance spectrum of a thin film of (HTZP)BiI was recorded and translated into an absorption spectrum according to the Kubelka-Munk remission function [۱۰]. The UV-Vis absorption spectrum shows an important absorption covering the majority of the UV-Vis-NIR region with intense broad band between ۲۰۰ and ۶۰۰ nm and a weak broad band between ۷۰۰ and ۱۱۰۰ nm which make the material suitable for photovoltaic solar cells application. Using the Tauc plot, we demonstrate the semiconductive property of the material with direct gap energy of ۲ eV, which is similar to Bi-based materials [۱۱,۱۲]. The photoluminescence spectrum recorded under an excitation wavelength of ۴۵۰ nm shows an intense emission band centered at ۵۱۷ nm. The obtained results of this work demonstrate that our material could be used as lead free luminescent semiconductors in optoelectronic devices.

کلیدواژه ها:

Bi-based semiconductor ، Bi-based photoluminescent materials ، Lead free hybrid material ، Photoluminescence