Enhancing Viologen's Electrochromism by Incorporating Thiophene: A Step Toward All‐Organic Flexible Device

Chaudhary, Anjali; Pathak, Devesh K.; Mishra, Suryakant; Yogi, Priyanka; Sagdeo, Pankaj R.; Kumar, Rajesh

doi:10.1002/pssa.201800680

Cited by 20 publications

(10 citation statements)

References 22 publications

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“…Raman spectrum, recorded in the backscattering geometry as shown in schematic (inset, Figure ), of the device in the OFF state (Figure ) shows the presence of EV and FPP in their corresponding neutral states when the device is in transparent state. The Raman modes of neutral EV 2+ can be clearly seen and the same has been identified using “*” mark (black curve, Figure ), which is consistent with the available reports. ,, Under this bias condition, the Raman modes of neutral FPP also can be seen (marked with “&”), which is at the same position in the Raman spectrum recorded from the FPP powder as a control experiment (Figure S1, Supporting Information). When the device is turned ON, the transparent to blue color switching (Figures and ) is accompanied by different Raman mode variation as compared to the OFF state (red curve, Figure ) and can be understood as follows.…”

Section: Resultssupporting

confidence: 88%

Electron Donor Ferrocenyl Phenothiazine: Counter Ion for Improving All-Organic Electrochromism

Chaudhary

Poddar

Pathak

et al. 2020

ACS Appl. Electron. Mater.

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Electron-donating properties of 3-ferrocenylethynyl-10-propyl-10H-phenothiazine (FPP) has been studied to be used as an efficient counter ion for application in a viologen-based organic electrochromic device to facilitate an efficient all-organic electrochromic device. The FPP molecule, when used as a counter ion with viologen, improves the switching time to less than half a second and exhibits lower operation voltage of ∼1 V and excellent stability for longer than 1800 s with a negligible amount of absorption loss. Spectroscopic and electrochemical measurement techniques have been used to understand the mechanism of bias-induced enhanced performance of the FPP−viologen-based solidstate electrochromic device. The device does not contain any liquid electrolytic medium to support its switching behavior and can also be fabricated on a plastic substrate for realization of a flexible all-organic electrochromic device. The viologen−FPP electrochromic device showed an optical contrast of more than 55% with a bias of 0 to 1 V when switched between OFF-(transparent) and ON-(blue) states. An excellent value of coloration efficiency of 460 cm 2 /C is obtained with a simple all-solid device geometry arrangement, making it the most efficient solid-state electrochromic device in the viologen family of devices.

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Section: Resultssupporting

confidence: 88%

Electron Donor Ferrocenyl Phenothiazine: Counter Ion for Improving All-Organic Electrochromism

Chaudhary

Poddar

Pathak

et al. 2020

ACS Appl. Electron. Mater.

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“…Upon biasing with −1.5 V, the device turns transparent from its initial blue color due to PB to PW conversion with no effect on EV 2+ . It is due to the reduction of PB film into transparent PW whereas EV remains unchanged, which is evident in Figure 5b where the EV peak 52 remains unaffected, indicated with *, whereas the PB peak at 2152 cm −1 gets shifted to a new positions 47 (marked by @ at 2104 and 2132 cm −1 ) signifying the conversion of PB to PW with a bias of −1.5 V. The unaffected EV peak under −1.5 V is also in good agreement with Figures 2c and 1b confirming unchanged neutral state of EV (EV +2 ). Thus, at this bias (the OFF state) the transparent species of PW and EV +2 make the whole device transparent allowing the whole visible spectrum to pass (Figure 3).…”

Section: ■ Results and Discussionmentioning

confidence: 87%

Prussian Blue-Viologen Inorganic–Organic Hybrid Blend for Improved Electrochromic Performance

Chaudhary

Pathak

Tanwar

et al. 2019

ACS Appl. Electron. Mater.

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Electrochromic performance of an inorganic−organic layered blend consisting of prussian blue and ethyl viologen has been studied in the form of a device designed to test its performance as well as identify the working mechanism. Initially the sky-blue colored device, consisting of prussian blue and ethyl viologen electrodes, switches reversibly between transparent and dark blue states on application of electrical bias of up to 1.5 V with appropriate polarity. Raman spectroscopic and electrochemical investigations along with control experiments very clearly suggest that reversible redox switching of the two species are responsible for the electrochromism in the device. The fabricated device shows a good optical modulation of more than 50% in dual wavelength region of 400 and 600 nm (blue and red), serving as dual wavelength filter, while maintaining its optical durability for more than 8400 s (1400 pulses) with high coloration efficiency. The inorganic−organic hybrid device comprised of prussian blue and ethyl viologen as its active materials evinces a better class of electrochromic performance apropos to individual electrochromic material.

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“…Apart from different inorganic electrochromic materials like metal oxides, , organic electrochromic materials (including conducting polymers) have been used very extensively for device purposes due to their advantages over inorganic ones. Polymers of thiophene, pyrrole, aniline and their derivatives, some organic compound like viologen , etc. span the organic electrochromic materials’ space .…”

Section: Introductionmentioning

confidence: 99%

Tracking Dynamic Doping in a Solid-State Electrochromic Device: Raman Microscopy Validates the Switching Mechanism

et al. 2020

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Solid-state electrochromic devices often need appropriate characterization to establish the real working mechanism for optimization and diagnosis. Raman mapping has been used here to track "dynamic doping", an important concept in organic electronics and in polythiophene-based solid-state electrochromic devices to understand and validate the mechanism of bias-induced redox-driven color switching. The proposed method demonstrates the live formation and movement of polarons which is best suited for in situ solid-state Raman spectroelectrochemistry. A 2-fold approach has been adopted here for this (1) by fabricating a working device in cross bar geometry followed by in situ spectroscopy to demonstrate the device functioning and (2) by carrying out Raman mapping from a device in custom-designed thin-film-transistor-like geometry to track and actually "see" the mechanism spectroscopically.

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Enhancing Viologen's Electrochromism by Incorporating Thiophene: A Step Toward All‐Organic Flexible Device

Cited by 20 publications

References 22 publications

Electron Donor Ferrocenyl Phenothiazine: Counter Ion for Improving All-Organic Electrochromism

Electron Donor Ferrocenyl Phenothiazine: Counter Ion for Improving All-Organic Electrochromism

Prussian Blue-Viologen Inorganic–Organic Hybrid Blend for Improved Electrochromic Performance

Tracking Dynamic Doping in a Solid-State Electrochromic Device: Raman Microscopy Validates the Switching Mechanism

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