Electro-optical analysis of PEDOT symmetrical electrochromic devices

Vergaz, Ricardo; Barrios, David; Sánchez‐Pena, José Manuel; Marcos, Carlos; Pozo, Cristina; Pomposo, José A.

doi:10.1016/j.solmat.2007.03.037

Cited by 30 publications

(14 citation statements)

References 5 publications

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“…Color contrast is defined as DT = [(T n -T r )/T n )] 9 100, where T n and T r are the transmittance at neutral and reduced states. DT obtained monitoring the transmittance at 550 nm, resulted in variations of less than 5 % from control device and, between 10 and 21 % from flexible device, with voltage at the range 2-2.5 V, reaching a maximum variation of 35 % upon 3.5 V. These results are at same order than values previously reported for PEDOT based electrochromic devices operating at same voltage range [21]. However, it is clear the positive influence of the iPrOH on the electrochromic response, when compared with the control device that was prepared with PEDOT:PSS films from pristine solution and electrolyte.…”

Section: Uv-vis Transmittancesupporting

confidence: 70%

Roll-to-roll processed PEDOT:PSS thin films: application in flexible electrochromic devices

Santos

Gavim

Silva

et al. 2016

J Mater Sci: Mater Electron

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In this paper, poly (3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid) denoted as PED-OT:PSS, a common material used as electrode in organic electronics or as charge balancing layer in electrochromic devices, was processed in thin film by roll-to-roll technique onto flexible substrate. Improved wettability was achieved when the ITO/PET substrate received a pre-treatment with isopropyl alcohol (iPrOH) and small amount of this alcohol was mixed with the PEDOT:PSS, as demonstrated by the reduction of contact angle. Besides allowing the preparation of uniform films in larger areas, this procedure also resulted in PEDOT:PSS films with increased conductivity, from *2 9 10 -4 Scm -1 up to *2.5 9 10 -4 Scm -1 . This arises from the effect of the alcohol that spreads out the isolating PSS moietes from the surface of conducting PEDOT moieties and/or change the PEDOT chain conformation, resulting in increased conductivity. These rollto-roll processed PEDOT:PSS films were tested in electrochromic devices having a polymer:solid electrolyte composite based on poly(ethylene oxide) and lithium perchlorate. This device was sealed by lamination procedure in air. Contrast between oxidized (light blue) and reduced (dark blue) state of PEDOT:PSS was monitored by UVVis transmittance. The use of iPrOH as additive resulted in improved electrochromic response with coloration efficiency (g d ) of 377 C -1 cm 2 after 0.3 s of switch time.

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Section: Uv-vis Transmittancesupporting

confidence: 70%

Roll-to-roll processed PEDOT:PSS thin films: application in flexible electrochromic devices

Santos

Gavim

Silva

et al. 2016

J Mater Sci: Mater Electron

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“…The high R P value for PEDOT (in oxidized state) is comparable to that reported for PEDOT in a symmetrical PEDOT device. 37 In the PEDOT-PB device, charge transfer impedance during reduction of PEDOT (À0.5 V to PEDOT, Fig. 7b) is 34 100 O and R CT at the counter electrode (+0.5 V to PB), wherein R CT = 3160 O and the redox process can be seen in Fig.…”

Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 99%

Electrochemistry of poly(3,4-ethylenedioxythiophene)-polyaniline/Prussian blue electrochromic devices containing an ionic liquid based gel electrolyte film

Deepa

Awadhia

Bhandari

2009

Phys. Chem. Chem. Phys.

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Electrochromic devices based on poly(3,4-ethylenedioxythiophene) (PEDOT) as the cathodic coloring electrode and polyaniline (PANI) or Prussian blue (PB) as the counter electrode containing a highly conductive, self-supporting, distensible and transparent polymer-gel electrolyte film encapsulating an ionic liquid, 1-butyl-1-methylpyrrolidiniumbis-(trifluoromethylsulfonyl)imide, have been fabricated. Polarization, charge transfer and diffusion processes control the electrochemistry of the functional electrodes during coloration and bleaching and these phenomena differ when PEDOT and PANI/PB were employed alternately as working electrodes. While the electrochemical impedance response shows good similitude for PEDOT and PANI electrodes, the responses of PEDOT and PB were significantly different in the PEDOT-PB device, especially during reduction of PB, wherein the overall amplitude of the impedance response is enormous. Large values of the coloration efficiency maxima of 281 cm 2 C À1 (l = 583 nm) and 274 cm 2 C À1 (l = 602 nm), achieved at À1.0 and À1.5 V for the PEDOT-PANI and PEDOT-PB devices have been correlated to the particularly low magnitude of charge transfer resistance and high polarization capacitance operative at the PEDOT-ionic liquid based electrolyte interface at these dc potentials, thus allowing facile ion-transport and consequently resulting in enhanced absorption modulation. Moderately fast switching kinetics and the ability of these devices to sustain about 2500 cycles of clear-to-dark and dark-to-clear without incurring major losses in the optical contrast, along with the ease of construction of these cells in terms of high scalability and reproducibility of the synthetic procedure for fabrication of the electrochromic films and the ionic liquid based gel electrolyte film, are indicators of the promise these devices hold for practical applications like electrochromic windows and displays.

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“…Specifically, resistance due to contacts and counter electrode contribute to

R_{S}^{d}

, Polarization resistance (

R_{P}^{d}

) and capacity (

C_{P}^{d}

) are ascribed to separation and accumulation of charges, CPE1 expresses the double layer capacity, CPE2 is introduced because of the rough surfaces and

Z_{W}^{d}

is Warburg impedance created by diffusion. As seen in Table ,

R_{S}^{d}

of the star‐shaped Tri‐(Ani) 4 ‐COOH device (124.0 Ω) is significantly lower than that reported for a PEDOT symmetrical device which is 386 Ω . Besides, the star‐shaped structure exerts a more profound influence onto its EIS results in Tri‐(Ani) 4 ‐COOH device: value of

R_{C T}^{d}

decreases to 2471 Ω and

C_{P}^{d}

arises to 1.184E‐6 F, moreover,

R_{P}^{d}

is dramatically lower for Tri‐(Ani) 4 ‐COOH device (60.89 Ω) than that of HOOC‐(Ani) 4 ‐COOH device (9350 Ω), implying that the ions from ionic liquid are more available for compensation in Tri‐(Ani) 4 ‐COOH device.…”

Section: Resultsmentioning

confidence: 85%

Self‐Doped Oligoaniline Electrochromic Devices: Fabrication and Effect of the Oligoaniline Molecular Architecture

et al. 2017

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A series of self‐doped oligoaniline derivatives, that is, carboxyl‐capped tetraaniline (HOOC‐(Ani)4‐COOH), carboxyl‐capped pentaaniline (HOOC‐(Ani)5‐COOH), carboxyl‐capped hexaaniline (HOOC‐(Ani)6‐COOH), and carboxyl‐capped star‐shaped tetraaniline (Tri‐(Ani)4‐COOH) in leucoemeraldine base state, were synthesized and characterized. The number of the aniline units was varied and a star‐shaped structure was designed to detect the influence of the molecular architecture on the electrochromic properties. The introduction of carboxylic groups into oligoaniline derivatives produced intermolecular hydrogen bonds, which contributed to their self‐doping capability. As a result, these oligoaniline derivatives presented reversible electrochromic properties at pH≥7, which could not be seen in pristine oligoanilines or polyanilines. Then, these oligoaniline derivatives were fabricated into electrochromic devices without an external acid dopant in the assembling process. Comprehensive electrochemical tests were conducted to investigate their electrochromic properties. The resulting devices showed good performances in spectroscopic, electrochemical, and in situ tests. Increasing the chain length contributed to an improved optical contrast, coloration efficiency, response time, and cycling stability. Meanwhile, introducing a star‐shaped structure also led to a better electrochromic performance. Moreover, electrochemical impedance spectroscopy and AFM tests were used to explore the mechanism to understand how the star‐shaped molecule facilitated the redox process.

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Electro-optical analysis of PEDOT symmetrical electrochromic devices

Cited by 30 publications

References 5 publications

Roll-to-roll processed PEDOT:PSS thin films: application in flexible electrochromic devices

Roll-to-roll processed PEDOT:PSS thin films: application in flexible electrochromic devices

Electrochemistry of poly(3,4-ethylenedioxythiophene)-polyaniline/Prussian blue electrochromic devices containing an ionic liquid based gel electrolyte film

Self‐Doped Oligoaniline Electrochromic Devices: Fabrication and Effect of the Oligoaniline Molecular Architecture

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