High Contrast Ratio and Rapid Switching Organic Polymeric Electrochromic Thin Films Based on Triarylamine Derivatives from Layer-by-Layer Assembly

Choi, Kyungsun; Yoo, Sung Jong; Sung, ‡ and Yung-Eun; Zentel, Rudolf

doi:10.1021/cm061484m

Cited by 67 publications

(46 citation statements)

References 26 publications

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“…[27] The molecular weight is M n = 7200 g mol À1 (DP n = 18) with a polydispersity of [28][29][30][31][32] and was also observed in other polymeric systems bearing TPA units. [33,34] Herein we use in situ spectroelectrochemical experiments in dichloromethane solutions (c polymer = 1.7 mm) under thin-layer diffusion conditions (40 mm) to study the coupling reaction. [35] An in-depth characterization of the first oxidation cycle together with the spectroscopic data is given in the Supporting Information.…”

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confidence: 99%

Electrochemically Induced Formation of Independent Conductivity Regimes in Polymeric Tetraphenylbenzidine Systems

2010

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[a] p-Conjugated organic polymers have gained increasing interest since their discovery because of their ability to become electrically conducting upon doping.[1] The understanding of the mechanism of conductivity in these materials is highly important both from a fundamental point of view [2] and for their applications in devices. [3][4][5] Conjugated polymers are nonconducting in the neutral state and conducting in the charged state. Electrochemical studies coupled with conductance measurements of conjugated polymers typically show conductivities over large potential ranges. [6,7] In the literature several models exist to describe the conductivity mechanism in conjugated polymers. [8][9][10][11] Probably the most established in the electrochemical literature is the bipolaron model, which is derived from solid-state materials and based on the band model. [9,12,13] Different aspects of this model are discussed in the literature. Upon increasing the oxidation level, first polarons (radical cations) and then bipolarons (dications) are formed. The bipolaron model explains conductivity in conjugated polymers with the transport of first locally stabilized polarons followed by transport of bipolarons. According to theoretical predictions, the broadening of the bipolaron states produces new unfilled valence bands and leads to metal-like conduction at high doping levels. A characteristic sigmoidal shape of conductivity as function of charging and the disappearance of the ESR signal at high charging support this view involving the transport of spinless bipolaronic charge carriers and not of electrons.[14] However, some experiments reveal a decrease of the conductivity after reaching the plateau at high doping levels, [6,[15][16][17] which cannot be unambiguously explained by a simple bipolaron conduction in conjugated polymers. Different explanations have been presented in the literature, for example, mixed valence exchange processes between polaron and neutral or polaron and bipolaron sites. [16,18] Wrighton reports that at high charging levels the decrease in conductivity can be attributed to localization of charges on the chains.[6] Very recently, Heinze et al. studied 3D hybrid networks consisting of dendritic cores of polyphenylene systems and hexathiophene oligomers crosslinking the dendritic cores.[19] Surprisingly, cyclic voltammetry coupled with in situ conductance measurements showed two independent regimes of conductivity which can be attributed to the hexathiophene oligomers and polyphenylene cores, respectively. A first analysis of this phenomenon supports the view that the conductivity of this material-especially of the hexathiophene segments-results from hopping processes [20][21][22] within mixed valence states. Hexathiophenes are interpreted as the oligomeric analoga of polythiophenes. Fichou and Garnier reported formation of polarons and bipolarons upon increased doping level by spectroscopic evidence.[23] However, no experimental data on the conductivity were shown that might have confirmed the bipo...

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confidence: 99%

Electrochemically Induced Formation of Independent Conductivity Regimes in Polymeric Tetraphenylbenzidine Systems

2010

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“…We believe that all these requirements are satisfied when the spin assembly method is employed, as previously demonstrated. [18][19][20][21][22] …”

Section: Resultsmentioning

confidence: 99%

“…[15,16] In the present study, we report the first example of phosphorescent-emitting and alternately structured host/ guest multilayer thin films based on water-soluble Ir(III)-complexes as guests and a carbazole-based host prepared by spin-assisted LbL assembly (hereafter termed as the spin assembly), which offers precise control of the bilayer thickness with large area uniformity as well as well-defined interfaces between layers, as described previously. [18][19][20][21][22] Using these unique features of the spin assembly method, we demonstrate that the emission intensity as well as emission colors can be simultaneously controlled or tuned by varying the energy transfer efficiency in one-dimensional (1D) multilayer thin films because of the change in film thickness of the non-emitting spacer layers between the donor and the acceptor layers.…”

Section: Introductionmentioning

confidence: 99%

Tunable Phosphorescent Emission through Energy Transfer within Multilayer Thin Films Based on a Carbazole‐Based Host and Ir(III)‐Complex Guest System

Kim

Lyu

Choi

et al. 2009

Macromol. Rapid Commun.

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A new method to tune both phosphorescence emission intensity and spectroscopic colors based on the alternatively structured host/guest multilayer thin films prepared by the spin-assisted LbL deposition is presented. Their emission characteristics are demonstrated with pairs of positively charged Ir-PEI complexes as guests and negatively charged CBZ-PAA as hosts. The phosphorescent emission of Ir-PEI complexes is enhanced by the energy transfer from the host to the guest and, additionally, this energy transfer can be finely tuned by the insertion of spacer layers between the phosphorescent donor and acceptor layers to vary the emission intensity as well as to render different emission colors.

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“…Triphenylamine is one kind of organic anodic electrochromic material. Being electron-rich, triphenylamine is easily oxidized to form stable polarons and a noticeable change in color always accompanies the oxidation process [30]. For triphenylamine itself, it shows colorless in the neutral state and green in the oxidized state.…”

Section: List Of Tablesmentioning

confidence: 99%

Heat resistant polymer electrolyte for enhanced organic electrochromic windows based on poly (3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)

2014

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High Contrast Ratio and Rapid Switching Organic Polymeric Electrochromic Thin Films Based on Triarylamine Derivatives from Layer-by-Layer Assembly

Cited by 67 publications

References 26 publications

Electrochemically Induced Formation of Independent Conductivity Regimes in Polymeric Tetraphenylbenzidine Systems

Electrochemically Induced Formation of Independent Conductivity Regimes in Polymeric Tetraphenylbenzidine Systems

Tunable Phosphorescent Emission through Energy Transfer within Multilayer Thin Films Based on a Carbazole‐Based Host and Ir(III)‐Complex Guest System

Heat resistant polymer electrolyte for enhanced organic electrochromic windows based on poly (3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)

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