Molecular-level electrochemical doping for fine discrimination of volatile organic compounds in organic chemiresistors

Kwon, Sooncheol; Pak, Yusin; Kim, Tae Hyuk; Park, Byoungwook; Kim, Jehan; Kim, Geunjin; Jo, Yong‐Ryun; Limbu, Saurav; Stewart, Katherine M. E.; Kim, Hyeonghun; Kim, Bong‐Joong; Jang, Soo‐Young; Kang, Hongkyu; Min, Jung‐Wook; Kim, Jinhyun; Jung, Gun Young; Lee, Kwanghee

doi:10.1039/d0ta05530a

Cited by 10 publications

(63 citation statements)

References 35 publications

(34 reference statements)

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“…The TT:SSIL(PF 6 – ) device shows high sensitivity (shown here, 250 ppm for acetone and 50 ppm for toluene), high selectivity (polar and nonpolar VOCs), a fast VOC on/off response (∼20 s), low power consumption (<1 μW), and room-temperature (∼25 °C) operations. In optimized devices, we have reported a limit of detection of ∼450 ppb for both acetone and toluene by TT:SSIL(PF 6 – ) . Compared with other reported VOC sensors based on organic semiconductors, the sensitivity for a range of polar and nonpolar VOCs such as acetone and toluene is among the optimum values, ,,,− while the stark selectivity observed between polar/nonpolar VOCs is unique to TT:SSIL(PF 6 – ) devices.…”

Section: Resultsmentioning

confidence: 85%

“…The 2D diffraction pattern of the neat TT film exhibits two distinct peaks along the out-of-plane direction with a strong lamellar stacking at q z (Å –1 ) = 0.23 and weak π–π stacking at q z (Å –1 ) = 1.83, indicating a semicrystalline morphology with an edge-on orientation. The neat SSIL(PF 6 – ) film has a high degree of crystallinity with a base-centered monoclinic herringbone structure . In contrast, the neat IL(TFSI – and BF 4 – ) films exhibit completely amorphous structures.…”

Section: Resultsmentioning

confidence: 99%

“…− ) film has a high degree of crystallinity with a base-centered monoclinic herringbone structure. 29 In contrast, the neat IL(TFSI − and BF 4 − ) films exhibit completely amorphous structures. Concerning the blend films, the semicrystalline nature of SSIL(PF 6 − ) is preserved in TT:SSIL-(PF 6…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…In optimized devices, we have reported a limit of detection of ∼450 ppb for both acetone and toluene by TT:SSIL(PF 6 − ). 29 Compared with other reported VOC sensors based on organic semiconductors, the sensitivity for a range of polar and nonpolar VOCs such as acetone and toluene is among the optimum values, 7,8,11,47−50 while the stark selectivity observed between polar/nonpolar VOCs is unique to TT:SSIL(PF 6 − ) devices. These detection limits are also competitive with sensors utilizing inorganic or hybrid materials.…”

mentioning

confidence: 89%

“…Recently, we have reported sensitive VOC detection (including propanol, acetone, chlorobenzene, and toluene) by both conjugated copolymer 29 and homopolymer 30 blended with ionic liquid (IL). These studies demonstrated the potential of conjugated polymer:ionic liquid blends to be used as VOC sensors; however, further development (for instance, sensitivity, selectivity, reliability, and response speed) was extremely slow due to the lack of fundamental understanding of the operating mechanism of these devices.…”

Section: ■ Introductionmentioning

confidence: 99%

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Solid-State Ionic Liquid: Key to Efficient Detection and Discrimination in Organic Semiconductor Gas Sensors

Limbu

Stewart

Nightingale

et al. 2021

ACS Appl. Electron. Mater.

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Π-conjugated polymers (π-CPs) blended with ionic liquids (ILs) have shown great potential for noninvasive diagnostics by transducing dielectric environmental changes induced by volatile organic compound (VOC) biomarkers into distinct electrical signals. However, the role of ILs in VOC sensing remains unclear, limiting further development of organic sensors for real commercialization. Herein, the key VOC detection and discrimination mechanisms in π-CP:IL sensors are identified. Three different ILs forming either the liquid or solid (semicrystalline) state at room temperature are investigated. Superior to the liquid-state ionic liquid (LSIL), the solid-state ionic liquid (SSIL) promotes strong, stable, and reversible electrochemical interaction (electric-field-driven doping) of π-CP yielding a significant increase in π-CP conductivity, which is a key prerequisite for reliable and sensitive VOC sensing. These interactions are further modulated by different VOC polarities enabling highly sensitive and selective detection of various VOCs. Advanced in situ electrochemical and structural measurements reveal that polar VOC interacts directly with SSIL reducing the π-electron density of π-CP, while nonpolar VOC induces strong electronic coupling between π-CP and SSIL. Our results identify the complex transducing mechanisms of organic VOC sensors and provide important insight into the materials design rule for high-performance sensors.

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

mentioning

confidence: 89%

Section: ■ Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Solid-State Ionic Liquid: Key to Efficient Detection and Discrimination in Organic Semiconductor Gas Sensors

Limbu

Stewart

Nightingale

et al. 2021

ACS Appl. Electron. Mater.

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Understanding Effects of Alkyl Side‐Chain Density on Polaron Formation Via Electrochemical Doping in Thiophene Polymers

Stewart,

Pagano,

Tan

et al. 2023

Advanced Materials

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Polarons exist when charges are injected into organic semiconductors due to their strong coupling with the lattice phonons, significantly affecting electronic charge transport properties. Understanding the formation and (de)localisation of polarons is therefore critical for further developing organic semiconductors as a future electronics platform. However, there have been very few studies reported in this area. In particular, there has been no direct in situ monitoring of polaron formation and identification of its dependence on molecular structure and impact on electrical properties, limiting further advancement in organic electronics. Herein we demonstrate how a minor modification of side chain density in thiophene‐based conjugated polymers affects the polaron formation via electrochemical doping, changing the polymers’ electrical response to the surrounding dielectric environment for gas sensing. We find that the reduction in side chain density results in a multistep polaron formation, leading to an initial formation of localised polarons in thiophene units without side chains. Reduced side chain density also allows the formation of a high density of polarons with less polymer structural changes. More numerous but more localised polarons generate a stronger analyte response but without the selectivity between polar and non‐polar solvents, which is different from the more delocalised polarons that show clear selectivity. Our results provide important molecular understanding and design rules for the polaron formation and its impact on electrical properties.This article is protected by copyright. All rights reserved

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A Flexible, Transparent Chemosensor Integrating an Inkjet‐Printed Organic Field‐Effect Transistor and a Non‐Covalently Functionalized Graphene Electrode

Lai

Vlamidis

Mishra

et al. 2021

Adv Materials Technologies

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portability, ease of use, and affordability, biochemical sensors are increasingly benefiting from the development of electronic technologies. In particular, the application of field-effect transistors (FETs) for biochemical sensing has attracted the attention of scientists since the demonstration of the ion-sensitive FET (ISFET) functionality. [1] FETs are capable of direct, label-free transduction of biochemical signals into electrical quantities and provide a local amplification that simplifies signal acquisition and processing. In addition, the specific properties of electronic technologies make this class of sensors ideal for the development of integrated, portable, user-friendly and affordable sensing systems. As FET-based biochemical sensors (namely bioFETs or chemFETs) are successfully used for broad biochemical sensing applications, [2][3][4] research has focused on providing these devices with novel properties that incorporate innovations of electronic technologies and materials science. In particular, mechanical flexibility and optical transparency are important for advanced biosensing devices. Mechanical flexibility ensures the possibility of adapting devices to complex shapes, and this property is fundamental to the development of new classes of Lab-on-a-Chip devices, [5][6][7] and more so for Point-of-Care, wearable, [8][9][10] or even implantable instrumentation. [11] Optical transparency is also crucial for device integration with wearable elements, [12] as well as when the integration of electronic and optical characterization is fundamental, such as in cell culturing or in medical applications, where optical inspection of analytes is fundamental. [13,14] In this sense, graphene and its derivatives have attracted the interest of the scientific community, because of their electrical properties, mechanical flexibility, robustness, durability, and transparency. Moreover, several studies have confirmed the biocompatibility and low cytotoxicity of graphene derivatives, [15] which makes them extremely attractive for biosensing applications. With respect to other conductive materials, graphene is highly stable and can be deposited by means of large-area processes, even by solution process techniques. State-of-theart, graphene-based bio-, and chemFETs have been reported for several applications, ranging from pH [16][17][18] and chemical This paper presents a novel chemical sensor that combines an organic, floating gate field-effect transistor and a functional graphene electrode, aimed at realizing the basic building block for novel biomedical sensor systems. A non-covalent functionalization of graphene with sensing peptides bearing a pyrene moiety is described as a way to provide graphene with chemical responsivity without affecting its electronic and optical features. Given the special properties of the materials and technologies used, and the intrinsic multi-modality of the active device, it is possible to develop a complete range of chemosensing devices by varying the chemical specificity of the immobi...

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Molecular-level electrochemical doping for fine discrimination of volatile organic compounds in organic chemiresistors

Abstract: Printable organic sensors fabricated from solution-processed π-conjugated polymers (π-CPs) are promising candidates to detect volatile organic compounds (VOCs) due to the intriguing physical, chemical and electronic properties of π-CPs. These...

Cited by 10 publications

References 35 publications

Solid-State Ionic Liquid: Key to Efficient Detection and Discrimination in Organic Semiconductor Gas Sensors

Solid-State Ionic Liquid: Key to Efficient Detection and Discrimination in Organic Semiconductor Gas Sensors

Understanding Effects of Alkyl Side‐Chain Density on Polaron Formation Via Electrochemical Doping in Thiophene Polymers

A Flexible, Transparent Chemosensor Integrating an Inkjet‐Printed Organic Field‐Effect Transistor and a Non‐Covalently Functionalized Graphene Electrode

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