Ultraviolet photoelectron spectroscopy of poly(pyridine-2,5-diyl), poly(2,2′-bipyridine-5,5′-diyl), and their K-doped states

Takayuki Miyamae, Daisuke Yoshimura, Hisao Ishii, Yukio Ouchi, Kazuhiko Seki, Takafumi Miyazaki, Tsuneaki Koike, Takakazu Yamamoto

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Abstract

Ultraviolet photoelectron spectra were measured using synchrotron radiation for two kinds of π-conjugated polymers, poly(pyridine-2,5-diyl) (PPy) and poly(2,2′-bipyridine-5,5′-diyl) (PBPy) which exhibit n-type electrically conducting properties. The two compounds show similar spectra and they were analyzed with MO calculations and the comparison with the data of related molecules. The ionization threshold energies of PPy and PBPy were found to be 6.3 and 6.35 eV, respectively. These values are higher than those of π-conjugated conducting polymers capable of p doping. Upon potassium doping of PBPy, two new states appeared in the originally empty energy gap and the intensity of the state at 0.65 eV from EF grows as the doping proceeds. This finding and the change of optical absorption spectra upon doping indicate that bipolaron bands are formed in K-doped PBPy. While K-doped PPy also shows similar gap states, it requires higher dopant concentration to create bipolaron bands than in the case of K-doped PBPy. The difference of the dependence on dopant concentration between K-doped PPy and K-doped PBPy is discussed based on the conformational difference between these polymers.

Original languageEnglish
Pages (from-to)2738-2744
Number of pages7
JournalThe Journal of Chemical Physics
Volume103
Issue number7
DOIs
Publication statusPublished - Jan 1 1995
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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    Miyamae, T., Yoshimura, D., Ishii, H., Ouchi, Y., Seki, K., Miyazaki, T., Koike, T., & Yamamoto, T. (1995). Ultraviolet photoelectron spectroscopy of poly(pyridine-2,5-diyl), poly(2,2′-bipyridine-5,5′-diyl), and their K-doped states. The Journal of Chemical Physics, 103(7), 2738-2744. https://doi.org/10.1063/1.470508