A donor-acceptor (D-A) cruciform conjugated luminophore DMCS-TPA was designed and synthesized.The DMCS-TPA solid shows both aggregation induced emission (AIE) effect and high contrast mechanochromic (MC) behavior with a remarkable spectral shift of 87 nm. The obvious fluorescence switching from yellowish green to orange can be realized by pressing at only 10 MPa or simply grinding.The photophysical properties, theory calculation and XPS results demonstrate that the extension of the conjugation length and subsequent enhancement of intramolecular charge transfer (ICT) transition are responsible for the improved MC performance. In addition, DMCS-TPA is readily deposited on the ITO electrode surface by the electrochemical method to form an electrochromic (EC) film with multiple colours showing (light green at 0 V, red at 1 V, grey at 1.1 V and blue at 1.45 V) and a high optical contrast of 65% at 769 nm. The results suggest that incorporation of electroactive moieties into luminophores to constitute D-A cruciform conjugated structures is a promising design strategy for preparing dual functional materials combining MC and EC properties.

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The core–shell composite film exhibits higher optical contrast, faster switching speed and better electrochemical stability.

Copolymer based on 4-(9H-carbazol-9-yl)-N,N-diphenylaniline (CDPN) and 3,4-ethylenedioxythiophene (EDOT) was electrochemically synthesized and characterized. Through electrochemical methods, FTIR spectroscopy and scanning electron microscopy (SEM) analysis, the resulting polymer was confirmed to be a copolymer rather than a blend or a composite of the respective homopolymers. Besides, the spectroelectrochemical and electrochromic properties of the copolymer (P(CDPN-co-EDOT)) films were investigated. According to the spectroelectrochemical analysis, the copolymer film revealed distinct electrochromic properties with four colors: claret red, green, cadetblue, and blue. At the neutral state of the copolymer, the π-π* transition absorption peak was located at 530 nm and the energy gap was calculated as 1.67 eV. The copolymer film showed a maximum optical contrast ( T%) of 36% in visible region with a switching time of 1.8 s and 43% in the near-IR region with a switching time of 2.5 s. The coloration efficiency (CE) of P(CDPN-co-EDOT) were calculated to be 332 cm 2 · C −1 (at 530 nm), 277 cm 2 · C −1 (at 810 nm) and 552 cm 2 · C −1 (at 1100 nm). Repeated cyclic voltammograms indicated that the copolymer had reasonable stability because of the existence of EDOT units.

A novel ferrocene-containing compound 6-(3,6-di(thiophen-2-yl)-9H-carbazol-9-yl)hexyl ferrocenecarboxylate (BTC-H-Fc) was synthesized by simple chemical route, and 3,6-di(thiophen-2-yl)-9H-carbazole (BTC) was prepared for comparison. Both of the homopolymers of BTC-H-Fc and BTC were successfully synthesized by electropolymerization and kept the redox activity upon repeated cycling between 0.0 V and 1.4 V. Compared to PBTC which could only showed two colors (yellow and purple), P(BTC-H-Fc) film could exhibit four colors (yellow, awny, purple and indigo-blue) as a consequence of mixing colors of main chain and Fc group. Meanwhile, P(BTC-H-Fc) film presented higher optical contrast of 52% and more excellent coloration efficiency (573.72 cm 2 C −1 ). All the results demonstrate that Fc could be a good choice as a functional group to improve the electrochromic properties of the electrochromic polymers.