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The Effect of Alkyl Spacers on the Mixed Ionic‐Electronic Conduction Properties of N‐Type Polymers
Author(s) -
Maria Iuliana P.,
Paulsen Bryan D.,
Savva Achilleas,
Ohayon David,
Wu Ruiheng,
Hallani Rawad,
Basu Aniruddha,
Du Weiyuan,
Anthopoulos Thomas D.,
Inal Sahika,
Rivnay Jonathan,
McCulloch Iain,
Giovannitti Alexander
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202008718
Subject(s) - alkyl , side chain , materials science , ethylene glycol , conjugated system , polymer , polymer chemistry , ionic bonding , ionic conductivity , aqueous solution , electrochemistry , electrolyte , chemical engineering , organic chemistry , chemistry , ion , electrode , composite material , engineering
Conjugated polymers with mixed ionic and electronic transport are essential for developing the complexity and function of electrochemical devices. Current n‐type materials have a narrow scope and low performance compared with their p‐type counterparts, requiring new molecular design strategies. This work presents two naphthalene diimide‐bithiophene (NDI‐T2) copolymers functionalized with hybrid alkyl‐glycol side chains, where the naphthalene diimide unit is segregated from the ethylene glycol (EG) units within the side chain by an alkyl spacer. Introduction of hydrophobic propyl and hexyl spacers is investigated as a strategy to minimize detrimental swelling close to the conjugated backbone and balance the mixed conduction properties of n‐type materials in aqueous electrolytes. It is found that both polymers functionalized with alkyl spacers outperform their analogue bearing EG‐only side chains in organic electrochemical transistors (OECTs). The presence of the alkyl spacers also leads to remarkable stability in OECTs, with no decrease in the ON current after 2 h of operation. Through this versatile side chain modification, this work provides a greater understanding of the structure‐property relationships required for n‐type OECT materials operating in aqueous media.