Tetramethylthiourea (TMTU) as an alternative redox mediator for electrochromic devices

Bogati, Shankar; Georg, Andreas; Jerg, Carmen; Graf, Wolfgang

doi:10.1016/j.solmat.2016.07.023

Cited by 32 publications

(22 citation statements)

References 17 publications

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“…The potentials distributed on each electrode were determined using an in situ potential measurement system following a previous method. [ 25 ] As shown in Figure 4b,c (also in Table S2, Supporting Information), E WE was larger with increasing LiI concentration under the same E ap of −1.8 V. The changing trend of E WE was consistent with the changing trend of conductivity (Figure S6, Supporting Information). The higher the concentration of LiI, the higher the conductivity of the electrolyte, which reduced the iR in Equation (3).…”

Section: Resultssupporting

confidence: 69%

“…Such a charge‐balancing reaction was governed by the concentration of the redox‐active species in solution, as derived from the Nernst equation. [ 25,38 ] Thus, the potential developed in the WE ( E WE ) was formulated by Equation (5)

\begin{matrix} η_{CE} + E_{WE} + i R = E_{ap} + E_{I^{-} / I_{3}^{-}} + \frac{R T}{n F} l n \frac{([], I_{3}^{-})}{([], I^{-})} \end{matrix}

where

E_{I^{-} / I_{3}^{-}}

represents the formal potential in the electrolyte media, and η CE and iR denote the overpotential and iR drop caused by the internal resistance, respectively. R, n, T , and F in Equation (5) are the universal gas constant, number of electrons accepted by I 3 − , absolute temperature, and Faraday constant, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…For example, a WO 3 ‐based ECD showed enhanced EC performance when it was assembled with an electrolyte containing a tetramethylthiourea redox couple. [ 24,25 ] Similarly, viologen‐based ECDs displayed fast switching times and high cycling stability in the presence of an I − /I 3 − redox mediator in a gelatin‐electrolyte. [ 26,27 ] However, POM‐based ECDs with redox couples in the electrolyte are not reported in literature.…”

Section: Introductionmentioning

confidence: 99%

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Charge‐Balancing Redox Mediators for High Color Contrast Electrochromism on Polyoxometalates

Wang

et al. 2020

Adv Materials Technologies

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POMs) recently emerged as promising inorganic materials due to their varying structures, high electrochemical activities, and EC performances. [11,12] The most common and widely investigated POM structure is the Keggin structure, which is applied in biochemical, electrochemical, and catalytic areas. [13] However, studies on the EC properties of Keggin-structured POMs are limited, and their reported EC performances were inferior to other POM types. [14] Several attempts were made to improve the EC performance, including modifying the molecular structure or atomic composition, and optimizing the nanostructures [15-19] Notably, for POM-based EC materials, these approaches were employed by simultaneously selecting and controlling their nanostructures. Porous TiO 2 nanoparticle films (TNFs) are successful POMs' hosts displaying satisfactory EC performances due to their large specific surface area and porous morphology. [20-23] Further increases in ΔT were obtained by assisting the EC reaction by charge-balancing species between the working and counter electrodes in a full cell structure. Although some full cell type ECDs were achieved with POMs, [20,23] charge-balancing reactions were rarely examined, possibly because of the complicated EC mechanism, which makes it difficult to select CBMs for POMs. To create a CBM, a redox active material or electron reservoir was coated on the counter electrode (film type) or dissolved in the electrolyte (solution type). To simplify the ECD structure and avoid increasing its thickness, the solution type could be promising for high-performance ECDs. For example, a WO 3-based ECD showed enhanced EC performance when it was assembled with an electrolyte containing a tetramethylthiourea redox couple. [24,25] Similarly, viologen-based ECDs displayed fast switching times and high cycling stability in the presence of an I − /I 3 − redox mediator in a gelatin-electrolyte. [26,27] However, POM-based ECDs with redox couples in the electrolyte are not reported in literature. Noticeably, POM-based ECDs suffer from limited electrolyte choices and low optical contrast (ΔT), and POM-based EC films are mainly operated in aqueous media. [28] Also, the limited electrochemical window (1.23 V) of the aqueous electrolyte restricted their broader application in ECDs. [29] In general, water can be electrolyzed, but generates bubbles at the voltage range for coloration and bleaching of EC materials. In a A nonaqueous charge-balancing electrolyte with a redox couple (I − /I 3 −) is investigated to improve the electrochromic (EC) performance of polyoxometalate (POM)-based electrochromic devices (ECDs). PW 12 O 40 3− (PW 12)-coated porous TiO 2 nanoparticle films (PWTNF) with different thicknesses are used as the working electrode. The optical contrast (ΔT) of the optimized PW 12-ECDs reached 59.4% with the electrolyte containing the I − /I 3 − redox couple. PW 12-ECDs also show a fast response time for bleaching (t b,90% = 1.9 s) and coloration (t c,90% = 3.1 s). On the contrary, without the I − /I 3 − redox ...

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Section: Resultssupporting

confidence: 69%

\begin{matrix} η_{CE} + E_{WE} + i R = E_{ap} + E_{I^{-} / I_{3}^{-}} + \frac{R T}{n F} l n \frac{([], I_{3}^{-})}{([], I^{-})} \end{matrix}

where

E_{I^{-} / I_{3}^{-}}

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Charge‐Balancing Redox Mediators for High Color Contrast Electrochromism on Polyoxometalates

Wang

et al. 2020

Adv Materials Technologies

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“…Such enhanced dual‐band EC performance was ascribed to the following Pt‐catalyzed redox reaction: 3I − ↔I 3 − + 2e − , as large faradaic currents during the redox reactions can trigger electron injection into the WO 3 lattice and capacitive surface charging. [ 86–87 ] Figure 8c–e shows the principle of WO 3 NR‐based EC devices in three different states. At open circuit potential (OCP), WO 3 is almost transparent, allowing for most VIS and NIR components to pass through the device, leading to a bright state (Figure 8c).…”

Section: Inorganic Ec Materialsmentioning

confidence: 99%

Recent Advances on Dual‐Band Electrochromic Materials and Devices

Zhai

Shen

et al. 2022

Adv Funct Materials

105

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Dual-band electrochromism is a phenomenon where materials can independently regulate the transmittance of visible (VIS) and near-infrared (NIR) light. Owing to their bistability, low energy consumption, and independent control over VIS and NIR regions, dual-band electrochromic (EC) devices have been of great significance to fully harnessing VIS and NIR light and building an energy-saving society. The past several years have witnessed the efforts put in developing novel EC materials to improve their dual-band optical performance through altering their composition, structural, and physicochemical features, which determine the optical behavior of dual-band EC devices. In this review, the concept, significance, working principle, and key influence factors of dual-band electrochromism are briefly introduced. Next, the up-to-date progress of dual-band EC materials including inorganic, organic, and composites materials are summarized, with a focus on material design, device fabrication, and performance optimization. Finally, the challenges and perspectives of dual-band EC materials and devices are also presented.

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“…Furthermore, in order to achieve a fast switching and device simplification, redox couples like I -/I 3 - [58][59][60] and tetramethylthioureea [62] were used in WO3 based ECDs as mediator and counter electrode, incorporated in the electrolyte. Likewise, the benefits of using ferrocene (Fc + /Fc) as redox mediator in viologen based ECDs, has also been reported [35,63], allowing device simplification to 3 [63] and 4 [35] layers.…”

Section: Introductionmentioning

confidence: 99%

Eco-friendly redox mediator gelatin-electrolyte for simplified TiO2-viologen based electrochromic devices

Danine

Manceriu

Fargues

et al. 2017

Electrochimica Acta

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Tetramethylthiourea (TMTU) as an alternative redox mediator for electrochromic devices

Cited by 32 publications

References 17 publications

Charge‐Balancing Redox Mediators for High Color Contrast Electrochromism on Polyoxometalates

Charge‐Balancing Redox Mediators for High Color Contrast Electrochromism on Polyoxometalates

Recent Advances on Dual‐Band Electrochromic Materials and Devices

Eco-friendly redox mediator gelatin-electrolyte for simplified TiO2-viologen based electrochromic devices

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