Swivel-Cruciform Configuration Induced Electrochromic Fast Switching Property of Donor-Acceptor Conjugated Polymer Containing 5,5 ′ -Bibenzothiadiazole

Abstract

A donor-acceptor (D-A) conjugated monomer (ST-BBT) constructed from the swivel-cruciform configuration of 5,5' - bibenzothiadiazole acceptor core and thiophene donor arm was synthesized via common chemical reactions. The corresponding polymer (pST-BBT) was successfully electrodeposited onto ITO glass via cyclic voltammetry (CV) method. Meanwhile, the linear-structure analogue (pST-BT) containing benzothiadiazole as acceptor unit and thiophene as donor unit was also obtained as reference. We investigated their electrochemical and optical properties, surface morphology, and electrochromic performances, respectively. Notably, pST-BBT exhibited the faster response speed (0.5s for discoloration and 2.5s for coloration) than pST-BT (1.0s for discoloration and 8.5s for coloration) under the same conditions. The introduction of 5,5' -bibenzothiadiazole with swivelcruciform configuration into the polymer backbone helped to optimize the surface morphology, speed up the ion diffusion process and even possess the possible microporous structure, which were all beneficial to enhance the electrochromic response speed. The swivel-cruciform molecular configuration was a promising structural strategy to construct the high-performanced electrochromic materials. (C) 2018 The Electrochemical Society.