A distinctive signature in the Raman and photoluminescence spectra of intercalated PbI₂

Abstract

Through correlated studies using scanning electron microscopy (SEM), Raman spectroscopy and low-temperature photoluminescence (PL) we have demonstrated that the intercalated PbI2 with ammonia, poly (vinyl alcohol) and polyacrylamide are characterized by a distinctive signature in the Raman and photoluminescence spectra. After intercalation, the Raman spectrum of PbI2 reveals an orthorhombic structure, identical with that observed on the micrometric scale, of KPbI3 rod-like particles resulting from the reaction between Pb(NO3)2 and KI, carried out in liquid media such as ethanol and acetonitrile. The rods and the intercalated PbI2 are characterized by a new and strong emission band at 2.23 eV (about 550 nm) that appears at 77 K under an excitation wavelength of about 340 nm. Modification of the Raman and PL spectra results from a compressing effect produced by the penetration between the PbI2 layers of different molecular species. The compression acting primarily on the iodine layers has the result of lowering the contribution of the 5p states of I− ions to the constitution of the electronic level situated at the top of valence band of PbI2, so that the photoluminescence of intercalated PbI2 acquires the characteristics of Pb2+ emission when it is dissolved in an alkali halide crystal.

A review of polytypism in lead iodide

“…PbI2 is used to study cluster formation [1,2] and to study thin films of various molecules that can be placed between the layers (intercalation) [3][4][5]. It is a candidate for use in image recording [6].…”

Comparative studies of optical absorption, photoluminescence and EPR spectra of PbMnI2 bulk layers and nanocrystals

“…E. Lifshitz et al [10,25] observed an emission band in PL spectra for platelet-like nanocrystals PbI 2 in this energy region and identified this peak with donor and acceptor sites at the interior part of the nanoparticles. N. Preda et al [26] observed an emission band with simple energy position in PL spectra for micrometric crystalline powder of PbI 2 obtained by mechanical crumbling of bulk crystals. They associated this peak with the presence of Pb 2+ ions usually produced near dislocations and cleavage defects in bulk crystals.…”

Producing BiI/BiOI Thin Films via Chemical Bath Deposition

“…Regarding nonlinear optic of bismuth iodine, the band gap of was about 2.0 eV. Rhombohedra structure was observed in the XRD analysis of BiI 3 . Each bismuth ion was octahedrally coordinated with six iodine ions, and each structure layer was consisted of three I-Bi-I sheets.…”

“…Inserting guest atoms or molecules into the interlayer spaces is easy to achieve, and leads to the variation of many physical properties, such as optical, electrical, crystalline structure [1][2][3][4] . Regarding nonlinear optic of bismuth iodine, the band gap of was about 2.0 eV.…”