Enhanced Raman scattering on lead iodide film

Lin Zhu; Hao Ma; He Wang; Peng Li; Lin Guo; Bing Zhao

doi:10.1016/j.saa.2019.117336

Enhanced Raman scattering on lead iodide film

Spectrochim Acta A Mol Biomol Spectrosc. 2019 Dec 5:223:117336. doi: 10.1016/j.saa.2019.117336. Epub 2019 Jul 4.

Authors

Lin Zhu¹, Hao Ma¹, He Wang¹, Peng Li¹, Lin Guo¹, Bing Zhao²

Affiliations

¹ State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China.
² State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China. Electronic address: zhaob@mail.jlu.edu.cn.

PMID: 31302565
DOI: 10.1016/j.saa.2019.117336

Abstract

Surface-enhanced Raman scattering (SERS) on organic-inorganic hybrid perovskites have been proved a promising SERS-active substrate. As its inorganic skeleton, lead iodide (PbI₂) also represents a novel semiconductor substrate material that serves as either a complement or an alternative to conventional metal-based SERS. Here, for the first time, enhanced Raman scattering (ERS) of 1,2-bis(4-pyridyl)ethylene (BPE) adsorbed on PbI₂ film is observed. To our surprise, we obtained the same ERS spectra on the PbI₂ as SERS spectra obtained on the perovskites, which demonstrates the enhancement of substrate comes from inorganic skeleton rather than organic-inorganic hybrid perovskites. Compared with the normal Raman spectrum of BPE molecules, we find the B_u mode of the BPE molecule was selectively enhanced. We demonstrate that it involves a charge transfer (CT) resonance mechanism and takes place between the HOMO of BPE and the conduction band edge of PbI₂. Moreover, the PbI₂ substrate performs good reproducibility, uniformity and good Raman enhancement (EF ≥ 10⁵). It is believed that this unusual discovery not only enables PbI₂ to be an enhanced substrate, which also provides a new advance toward a better understanding of SERS chemical mechanism.

Keywords: Raman charge-transfer perovskites.