A heavily doped D-D′-type polymer with metal-like carrier transport via hybrid doping

Ayushi Tripathi, Yoonjoo Lee, Changhwa Jung, Soohyun Kim, Soonyong Lee, Woojin Choi, Chaeyeon Park, Young Wan Kwon, Hyunjung Lee, Han Young Woo

Research output: Contribution to journalArticlepeer-review

Abstract

A new donor-donor (D-D′)-type polymer (PIDTSCDTS) based on electron-rich indacenodithiophene (IDT) and cyclopentadithiophene (CDT) moieties is synthesized with extended π-conjugation and pronounced chain planarity through substitution with sp2-hybridized alkenyl side chains. Its thermoelectric (TE) properties are studied in detail depending on the doping methods: sequential doping (SqD), solution-mixed doping (MxD), and hybrid doping (HyD) with AuCl3 and FeCl3 as p-dopants. The carrier generation and transport depend strongly on the doping method. A higher conductivity (σ) of up to ∼500 S cm−1 is achieved using HyD (compared with other methods) owing to the significantly higher (bi)polaron generation (of up to ∼1021 cm−3) by doping both the amorphous and crystalline regions. Analyzing the relationship between the Seebeck coefficient (S) and the conductivity (σ) based on the Kang-Snyder model, metal-like carrier transport is observed for polymers obtained via SqD and HyD, which has been barely reported in organic TE polymers. The higher transport coefficient (σE0) in the HyD films reduces the S-σ trade-off relation, leading to a larger maximum power factor, PFmax, of ∼40 μW m−1 K−2 with simultaneously enhanced σ and S values compared with SqD films (16 μW m−1 K−2). To further optimize the TE properties, the degenerate doping and band-like carrier transport with maximizing the σE0 need to be carefully considered for the molecular design and doping process.

Original languageEnglish
Pages (from-to)5646-5656
Number of pages11
JournalJournal of Materials Chemistry C
Volume11
Issue number17
DOIs
Publication statusPublished - 2023 Mar 30

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation (NRF) of Korea (2020M3H4A3081814, 2019R1A6A1A11044070, 2021R1A4A1030944 and 2021R1A2C2008325).

Publisher Copyright:
© 2023 The Royal Society of Chemistry.

ASJC Scopus subject areas

  • General Chemistry
  • Materials Chemistry

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