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Self‐Doped Oligoaniline Electrochromic Devices: Fabrication and Effect of the Oligoaniline Molecular Architecture
Author(s) -
Gong Chen,
Yang Jiping,
Cao Linyu,
Gao Yuchong
Publication year - 2017
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201600637
Subject(s) - electrochromism , materials science , electrochromic devices , electrochemistry , dopant , doping , nanotechnology , dielectric spectroscopy , photochemistry , optoelectronics , chemistry , electrode
A series of self‐doped oligoaniline derivatives, that is, carboxyl‐capped tetraaniline (HOOC‐(Ani) 4 ‐COOH), carboxyl‐capped pentaaniline (HOOC‐(Ani) 5 ‐COOH), carboxyl‐capped hexaaniline (HOOC‐(Ani) 6 ‐COOH), and carboxyl‐capped star‐shaped tetraaniline (Tri‐(Ani) 4 ‐COOH) in leucoemeraldine base state, were synthesized and characterized. The number of the aniline units was varied and a star‐shaped structure was designed to detect the influence of the molecular architecture on the electrochromic properties. The introduction of carboxylic groups into oligoaniline derivatives produced intermolecular hydrogen bonds, which contributed to their self‐doping capability. As a result, these oligoaniline derivatives presented reversible electrochromic properties at pH≥7, which could not be seen in pristine oligoanilines or polyanilines. Then, these oligoaniline derivatives were fabricated into electrochromic devices without an external acid dopant in the assembling process. Comprehensive electrochemical tests were conducted to investigate their electrochromic properties. The resulting devices showed good performances in spectroscopic, electrochemical, and in situ tests. Increasing the chain length contributed to an improved optical contrast, coloration efficiency, response time, and cycling stability. Meanwhile, introducing a star‐shaped structure also led to a better electrochromic performance. Moreover, electrochemical impedance spectroscopy and AFM tests were used to explore the mechanism to understand how the star‐shaped molecule facilitated the redox process.