Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9812854 | Thin Solid Films | 2005 | 9 Pages |
Abstract
Infrared spectra of six charge transfer complexes of lead phthalocyanine (PbPc), namely, PbPc-I2, PbPc-TCNQ, PbPc-DDQ, PbPc-chloranil, PbPc-TCNE and PbPc-TNF, where TCNQ=7,7,8,8-tetracyano-1,4-quinodimethane, DDQ=2,3-dichloro-5,6-dicyano-p-benzoquinone, TCNE=tetracyano-p-ethylene and TNF=2,4,5,7-tetranitro-9-fluorenone have been studied in the range of 400-4000 cmâ1. The analysis of featureless absorption is carried out for studying transition across the Peierls gap of 0.225 eV. The electronic absorption envelopes at 1500, 1100 and 3400 cmâ1 are found to have Gaussian shapes and not the degenerate oscillators, as found in purely organic conductors. There is a pairing of two electrons on phthalocyanine ligand as required in Little's model, and consequently, the electronic absorption envelope is a doublet. Electronic absorption envelope is a doublet showing two peaks at 1500 and 1100 cmâ1, indicating a two-electron problem in PbPc. Metal-ligand vibrations between 400 and 700 cmâ1 lead to indirect transition between the valence and conduction bands and phonon-mediated coupling between metal chains and the side chains.
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Authors
A.T. Oza, S.G. Patel, R.G. Patel, S.M. Prajapati, Rajiv Vaidya,