Abstract:Electrochromic polymer (ECPblack) demonstrates an ultrahigh contrast ratio (over 80%) in most of the visible regions, and its electrochemical and electrochromic behaviors remarkably accelerate by doping nanotube/polytriarylamine.
“…The oxidized PI-2a film showed weaker absorption intensity in the blue region than that in the green and red regions and almost no absorption in the near-IR region. The phenomena of broader absorption peak of oxidized PI-1a film (compared to PI-2a film) could be attributed to the longer conjugation length, which enhanced charge carrier delocalization compared to oxidized PI-2a film 19 .Fig. 3Electrochromic behaviors of EC Polyimides.…”
Colorless-to-colorful switching electrochromic polymers with very high contrast ratio are unattainable and attractive for the applications of smart wearable electronics. Here we report a facile strategy in developing colorless-to-colorful switching electrochromic polyimides by incorporating with alicyclic nonlinear, twisted structures and adjusted conjugated electrochromophores, which minimize the charge transfer complex formation. It is noted that, by controlling the conjugation length of electrochromophore, the colorless-to-black switching electrochromic polymer film (PI-1a) exhibites an ultrahigh integrated contrast ratio up to 91.4% from 380 to 780 nm, especially up to 96.8% at 798 nm. In addition, PI-1a film with asymmetric structure also demonstrates fast electrochemical and electrochromic behaviors (a switching and bleaching time of 1.3 s and 1.1 s, respectively) due to the loose chain stacking, which provides more pathways for the penetration of counterion. Moreover, the colorless-to-black EC device based on PI-1a reveals an overall integrated contrast ratio up to 80%.
“…The oxidized PI-2a film showed weaker absorption intensity in the blue region than that in the green and red regions and almost no absorption in the near-IR region. The phenomena of broader absorption peak of oxidized PI-1a film (compared to PI-2a film) could be attributed to the longer conjugation length, which enhanced charge carrier delocalization compared to oxidized PI-2a film 19 .Fig. 3Electrochromic behaviors of EC Polyimides.…”
Colorless-to-colorful switching electrochromic polymers with very high contrast ratio are unattainable and attractive for the applications of smart wearable electronics. Here we report a facile strategy in developing colorless-to-colorful switching electrochromic polyimides by incorporating with alicyclic nonlinear, twisted structures and adjusted conjugated electrochromophores, which minimize the charge transfer complex formation. It is noted that, by controlling the conjugation length of electrochromophore, the colorless-to-black switching electrochromic polymer film (PI-1a) exhibites an ultrahigh integrated contrast ratio up to 91.4% from 380 to 780 nm, especially up to 96.8% at 798 nm. In addition, PI-1a film with asymmetric structure also demonstrates fast electrochemical and electrochromic behaviors (a switching and bleaching time of 1.3 s and 1.1 s, respectively) due to the loose chain stacking, which provides more pathways for the penetration of counterion. Moreover, the colorless-to-black EC device based on PI-1a reveals an overall integrated contrast ratio up to 80%.
“…Suzuki coupling polymerization yielded the polymer with M1, M2, M3, and M6 in Figure 2. The synthesis processes are described in the Supplementary Information and in our previous work [15,19,20]. The details of C6 are given in the supplementary data (Figures S1 and S2), while the data for C1, C2, and C3 are derived from our previous work.…”
Section: Methodsmentioning
confidence: 99%
“…b Calculated from the UV absorption spectrum of the polymer films using the equation: band gap (eV) = 1240/λonsetabs. c Data of C2 derived from our previous work [15], and C1, C3 from references [19,20].…”
In this work, polymers of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-triphenylamine] with side chains containing: pyrene (C1), diphenyl (C2), naphthalene (C3), and isopropyl (C6) structures were synthesized via a Suzuki coupling reaction. The structures were verified using NMR and cyclic voltammetry measurements provide the HOMO and LUMO of the polymers. The polymer with pyrene (C1) and naphthalene (C3) produced photoluminescence in the green while the polymer with the side chain containing diphenyl (C2) and isopropyl (C6) produce dual emission peaks of blue-green photoluminescence (PL). In order to examine the electroluminescence properties of the polymers, the solutions were spin-coated onto patterned ITO anode, dried, and subsequently coated with an Al cathode layer to form pristine single layer polymer LEDs. The results are compared to a standard PFO sample. The electroluminescence spectra resemble the PL spectra for C1 and C3. The devices of C2, C3, and C6 exhibit voltage-dependent EL. An additional red emission peak was detected for C2 and C6, resulting in spectra with peaks at 435 nm, 490 nm, and 625 nm. The effects of the side chains on the spectral characteristics of the polymer are discussed.
“…Many state‐of‐the‐art ECPs have been developed but with slow switching speed, which is the main bottle‐neck for their practical applications. Nevertheless, the molecular‐design strategy to improve the switching speed and coloration efficiency (CE) is rarely explored.…”
Solution‐processable electrochromic polymers (ECPs) with high performance are urgently needed for extensive applications. Nevertheless, they suffer from slow switching speed because of low ionic conductivities. Herein, we present an effective strategy to improve the contrast and switching speed in ECPs via facile side‐chain engineering. A novel electrochromic thieno[3,2‐b]thiophene‐based polymer (PmOTTBTD) is designed and successfully synthesized by introducing oligo(ethylene oxide) side chains with high ionic conductivity. Compared to the counterpart POTTBTD without modification by oligo(ethylene oxide) chains, PmOTTBTD demonstrates nearly double contrast (42 % vs. 24 %) with a fast oxidation switching process that just takes half of the time when detected under 400 nm, as well as much higher coloration efficiencies (e. g. 239.04 cm2 C−1 vs. 226.26 cm2 C−1 @ 400 nm and 314.04 cm2 C−1 vs. 174.00 cm2 C−1 @ 650∼700 nm). Besides, PmOTTBTD exhibits excellent stability with negligible decay after 3000 cycles. Our work suggests a facile strategy that could be adopted to realize high‐performance ECPs via molecular design tuning.
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