Electrosynthesis and characterization of a neutrally colorless electrochromic material from poly(1,3-bis(9H-carbazol-9-yl)benzene) and its application in electrochromic devices

1.3-Bis(9H-carbazol-9-yl)benzene monomer (BCB) is successfully synthesized. Poly(1,3-bis(9H-carbazol9-yl)benzene) (PBCB) is electrochemically synthesized and characterized. The PBCB shows high outstanding optical contrast (60.98%) and reasonable transparency, with color changes from desirable transparent colorless to yellowish green, and then to green color upon the application of potentials ranging from 0 to 1.25 V. The color switching time and bleaching time of the PBCB film are 2.07 s and 0.45 s at 427 nm. Electrochromic device (ECD) based on PBCB and poly(3,4-ethylenedioxythiophene) (PEDOT) is also constructed and characterized. PBCB/PEDOT device shows a maximum contrast (Delta T%) of 26.64% at 427 nm with response time of 0.90s and of 43.67% at 625 nm with response time of 0.66 s. respectively. Particularly, the device exhibits transmissive blue at neutral state, good optical memory ability and remarkable stability after 1000 cycles. These properties make the polymer a suitable material for electrochromic applications. (C) 2012 Elsevier Ltd. All rights reserved.