Flexible Electrochromic Devices Based on Optoelectronically Active Polynorbornene Layer and Ultratransparent Graphene Electrodes

Abstract

Novel electrochromic polynorbornenes poly(NBPYTPAM) and poly(HNBPYTPAM), containing electroactive chromophores, were prepared via ring-opening metathesis polymerization (ROMP) from a new norbornene derivative (NBPYTPAM) using Grubbs’ catalyst and followed by hydrogen reduction. The glass transition temperatures (T g) of poly(NBPYTPAM) and hydrogenated poly(HNBPYTPAM) were 190 and 175 °C, respectively. The cyclic voltammogram of the poly(HNBPYTPAM) film cast onto flexible graphene-coated polyethylene terephthalene (PET) substrates exhibited two reversible oxidation redox couples at 1.0 and 1.9 V. Flexible electrochromic devices were fabricated from the electroactive polymers and graphene-coated PET substrates. The electrochromic characteristics of poly(HNBPYTPAM) showed excellent stability and reversibility, with multistaged color changes from its yellow neutral form to green and then to dark-blue.

High-Performance Electrochromic Devices Based on Poly[Ni(salen)]-Type Polymer Films

“…In general, the voltammetric responses of polymeric films stabilised after 5 scans, which correspond to the typical "film conditioning". 43,45 The coulometric data revealed Γ = 0.31 and 1.13 µmol cm -2 for poly [1] and poly [2], respectively, suggesting greater polymerization efficiency for poly [2].…”

“…The doping level (n) values used for Γ determination were calculated from comparison of coulometric data for films deposition and cycling in 0.1 mol dm -3 LiClO4/CH3CN solution with the Pt electrode, as described in literature, 32,40 considering that the obtained n-values are valid for other electrode substrates; the n-values were found to be n = 0.69 and 0.08 for poly [1] and poly [2] …”

“…43,44 In the second and subsequent voltammetric cycles (5 th cycle in Table S1), a new peak appears at Epa ≈ 0.42 V for the [Ni(3-Mesalen)] system which is assigned to polymer film oxidation deposited during the previous cycle(s); 43,44 in the reverse cathodic, the peaks at Epc = 0.64 and 0.22 V are due to the oligomers and polymer film reductions. In the case of [Ni(3-MesaltMe)], two new peaks appear during the second and subsequent scans (5 th cycle in Table S1) The voltammetric responses of the as-prepared poly [1] and poly [2] films in the electrolyte solutions LiClO4/CH3CN and LiClO4/PC 0.1 mol dm -3 are depicted in Figure 2 and, in Table S2, are summarized the potential peak values. We note additional anodic charge in the response to the first voltammetric cycle in background electrolyte.…”

“…2,3,4 Currently, EC materials are mainly applied in smart windows for green architecture 5 and in anti-glare rear view mirrors. 6 Other proposed applications are in displays of portable and flexible electronic devices, including smart cards, re-usable price labels and electronic papers, 7,8,9 protective eyewear 10 and in textiles for adaptative camouflage or simply for fashion.…”

“…Consequently, in this paper we report the preparation and study of two novel electrochromic systems based on the electroactive polymers: poly[Ni(3-Mesalen)], N,N'-bis(3-methylsalicylideneiminate) nickel(II) (poly [1]), and poly[Ni(3-MesaltMe)], N,N'-2,3-dimethylbutane-2,3-dyil-bis(3-methylsalicylideneiminate) nickel(II) (poly [2]); both salen ligands have a methyl group in the 3-position of each salicylaldehyde moiety and differ on the absence/presence of methyl substituents in the imine bridge, respectively.…”