Volume 27, Issue 22 p. 6696-6700
Communication

The Simplest Model for Doped Poly(3,4-ethylenedioxythiophene) (PEDOT): Single-crystalline EDOT Dimer Radical Cation Salts

Ryohei Kameyama

Ryohei Kameyama

The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581 Japan

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Tomoko Fujino

Corresponding Author

Tomoko Fujino

The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581 Japan

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Shun Dekura

Shun Dekura

The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581 Japan

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Mitsuaki Kawamura

Mitsuaki Kawamura

The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581 Japan

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Taisuke Ozaki

Taisuke Ozaki

The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581 Japan

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Hatsumi Mori

Corresponding Author

Hatsumi Mori

The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8581 Japan

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First published: 11 January 2021
Citations: 6

Graphical Abstract

Shortest oligomer models for doped PEDOT: Single-crystalline dimer models for doped poly(3,4-ethylenedioxythiophene) (PEDOT) were developed to understand the underlying conduction mechanism of doped PEDOT. The models exhibited one-dimensional π-stacking single-crystal structures possessing half-filled band structures with exclusively high intracolumnar orbital interactions, implying the origin of the excellent conductivity of doped PEDOT.

Abstract

Although doped poly(3,4-ethylenedioxythiophene) (PEDOT) is extensively used in electronic devices, their molecular-weight distributions and inadequately defined structures have hindered the elucidation of their underlying conduction mechanism. In this study, we introduce the simplest discrete oligomer models: EDOT dimer radical cation salts. Single-crystal structural analyses revealed their one-dimensional (1D) columnar structures, in which the donors were uniformly stacked. Band calculations identified 1D metallic band structures with a strong intracolumnar orbital interaction (band width W≈1 eV), implying the origin of the high conductivity of doped PEDOT. Interestingly, the salts exhibited semiconducting behavior reminiscent of genuine Mott states as a result of electron–electron repulsion (U) dominant over W. This study realized basic models with tunable W and U to understand the conduction mechanism of doped PEDOT through structural modification in oligomers, including the conjugation length.