THE INTERCALATION OF PbI_2 WITH 2,2'-BIPYRIDINE EVIDENCED BY PHOTOLUMINESCENCE, FT-IR AND RAMAN SPECTROSCOPY

摘要

Hybrid material based on PbI_2 intercalated with 2,2'-bypiridine (BIPY) was investigated by correlated studies of photoluminescence, infrared absorption and Raman spectroscopy. The PbI_2(BIPY) intercalated compound has been synthesized by the chemical reaction of KI and Pb(NO_3)_2 in aqueous BIPY solution. The optical studies reveal different properties for the hybrid material in comparison with those of pure PbI_2 and BIPY. In the photoluminescence spectrum of the intercalated compound, recorded at liquid nitrogen temperature a new intense band emission with maximum at 2.07 eV is observed. The excitation spectrum reveals a broad band featured by several maxima at 2.77, 3.34 and 3.70 eV. New absorption bands at about 1589, 1489, 1435, 1312, 1009 cm~(-1) are observed in the IR spectrum of PbI_2(BIPY). The Raman spectrum of intercalated compound discloses new lines at 67, 83, 127 cm~(-1) and the shift of two Raman lines from 994 cm~(-1) to 1010 cm~(-1) and from 1045 cm~(-1) to 1060 cm~(-1). A charge transfer process, leading to the formation of lead-BIPY coordination complexes, is considered as responsible for the strong host-guest interaction revealed by almost all experimental data.