Shubhradip Guchait

Université de Strasbourg

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Martin Brinkmann

Université de Strasbourg

Nicolas Leclerc

Institut de Chimie et Procédés pour l'Energie, l'Environnement et la Santé

Laurent Herrmann

Centre National de la Recherche Scientifique

Pablo Durand

Institut de Chimie et Procédés pour l'Energie, l'Environnement et la Santé

Huiyan Zeng

Institut Charles Sadron

Natalie Banerji

University of Bern

Badr Jismy

Institut de Chimie et Procédés pour l'Energie, l'Environnement et la Santé

Yuhan Zhong

Zhejiang University

Céline Kiefer

Centre National de la Recherche Scientifique

Aditya Dash

Heidelberg University

Cooperative Institutions

Centre National de la Recherche Scientifique

Université de Strasbourg

Institut Charles Sadron

Institut de Physique et Chimie des Matériaux de Strasbourg

University of Bern

Institut de Chimie et Procédés pour l'Energie, l'Environnement et la Santé

Institut de Chimie

Queen Mary University of London

Université de Tours

University of Cambridge

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High-Temperature Rubbing: An Effective Method to Fabricate Large-Scale Aligned Semiconducting and Conducting Polymer Films for Applications in Organic Electronics

Macromolecules (2023)

Shubhradip Guchait Yuhan Zhong Martin Brinkmann

Conjugated polymers (CPs) are ubiquitous in plastic electronics in the form of semiconducting and conducting polymers that are central in devices such as solar cells, field effect transistors, and thermoelectric generators. Exploiting the anisotropic properties of such conjugated materials calls for advanced and effective methods of growth and orientation. First, this contribution reviews different alignment methods of conjugated polymers used in plastic electronics. Second, we present the state of the art for the method of high-temperature rubbing that was extensively used to fabricate aligned polymer semiconductors (PSC) and conducting polymer (CP) films. Examples are given to illustrate how this versatile method of large-scale orientation can be used to design devices with anisotropic opto-electronic properties. Finally, we emphasize the recent progress made in the fabrication of highly ordered and oriented CPs by controlled doping of well-crystallized PSCs such as regioregular poly(3-hexylthiophene-2,5-diyl) and poly[2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene]. The way dopant molecules are introduced into and modify the crystal lattice of these PSCs is presented. The impact of the semi-crystalline structure of the polymers on doping and resulting thermoelectric performances of oriented thin films is discussed.

Rubbing

Organic Electronics

Organic semiconductor

10.1021/acs.macromol.3c01073

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Citations (15)

Étude de l'intercalation de dopants dans les cristaux de polymères semi-conducteurs par microscopie électronique en transmission (TEM), spectroscopie de rétrodiffusion de Rutherford (RBS) et spectroscopie UV-vis-NIR polarisée

Yuhan Zhong Shubhradip Guchait Viktoriia Untilova Laurent Hermann D. Müller

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A Label‐Like Monolithic Organic Thermoelectric Generator Enabled by Local Inkjet Doping of Aligned Polymer Films

Advanced Energy Materials (2025)

Nathan Pataki James Shubhradip Guchait Badr Jismy Nicolas Leclerc Adrica Kyndiah

Abstract The proliferation of distributed microelectronics and sensors necessitates adaptable, scalable, and cost‐effective power supplies. Organic thermoelectric generators (TEGs) that promise to harness heat sustainably and cost‐effectively are seen as pivotal elements in shaping future sensor infrastructures. Recent strides in morphological control through the alignment of conjugated polymer backbones have enhanced the thermoelectric performance of doped organic semiconductors to record values, matching expectations for real applications. However, the hurdles in crafting and deploying organic TEGs effectively exploiting aligned polymer films remain unexplored. This work presents a design and fabrication method to incorporate aligned films into a thin label‐like TEG. Thin films of regioregular poly(3‐hexylthiophene) (P3HT) and poly(2,5‐bis((7‐butoxyheptyl)thiophen‐2‐yl)thieno[3,2‐ b ]thiophene) (PBTTT‐ 8 O) are aligned via high‐temperature rubbing technique inducing a high degree of anisotropy in their charge transport properties. The crystal structure and anisotropy of the films are exploited to realize monolithic TEGs by patterning conductive thermoelements via local inkjet doping of films transferred on ultrathin parylene substrates. The TEGs based on aligned P3HT and PBTTT‐ 8 O exhibit exceptional TEG power factors of 0.33 and 1.04 nW cm −2 K −2 , respectively. Lastly, as a proof‐of‐concept use case for the TEGs, a thermoelectrically‐powered volume‐indicating label is presented as a potential application in the healthcare and food industries.

Thermoelectric generator

10.1002/aenm.202404656

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Ultra-high µC* beyond 10 000 F cm-1 V-1 s-1 in organic electrochemical transistors

Research Square (Research Square) (2023)

Olivier Bardagot Pablo Durand Shubhradip Guchait Gonzague Rebetez Priscila Cavassin

Abstract Organic electrochemical transistors (OECTs) are the heart of promising high-sensitivity biosensors, electrophysiological monitors, and neuromorphic devices. In a context of growing interest for such strategic electronics, we investigate a novel PBTTT polymer bearing single ether side chains (PBTTT-8O) in OECTs. Pristine, non-aligned, devices match state-of-the-art transconductance, confirming the value of single ethers for designing next-generation organic mixed ionic-electronic conductors (OMIECs). Moreover, a ten-fold enhancement of 𝜇C*, reaching 12 000 F cm-1 V-1 s-1, is achieved by unidirectional alignment of PBTTT-8O, opening doors to unprecedented device sensitivity. Such improvement is mainly attributed to enhanced hopping along ordered polymer chains, resulting in ultra high mobility over 25 cm2 V-1 s-1. Interestingly, aligned channels dope twice and dedope fifteen times faster than pristine ones, offering a path to achieve rapid ON/OFF device switching. This study reports an easily transferable solution to concomitantly boost the signal amplification and switching speed of bioelectronic devices.

10.21203/rs.3.rs-3221543/v1

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Interplay between Side Chain Density and Polymer Alignment: Two Competing Strategies for Enhancing the Thermoelectric Performance of P3HT Analogues

Chemistry of Materials (2023)

Peter A. Gilhooly‐Finn Ian E. Jacobs Olivier Bardagot Yasser Zaffar Antoine Lemaire

A series of polythiophenes with varying side chain density was synthesized, and their electrical and thermoelectric properties were investigated. Aligned and non-aligned thin films of the polymers were characterized in the neutral and chemically doped states. Optical and diffraction measurements revealed an overall lower order in the thin films with lower side chain density, also confirmed using polarized optical experiments on aligned thin films. However, upon doping the non-aligned films, a sixfold increase in electrical conductivity was observed for the polythiophene with the lowest side chain density compared to poly(3-hexylthiophene) (P3HT). We found that the improvement in conductivity was not due to a larger charge carrier density but an increase in charge carrier mobility after doping with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). On the other hand, doped aligned films did not show the same trend; lower side chain density instead led to a lower conductivity and Seebeck coefficient compared to those for P3HT. This was attributed to the poorer alignment of the polymer thin films with lower side chain density. The study demonstrates that optimizing side chain density is a synthetically simple and effective way to improve electrical conductivity in polythiophene films relevant to thermoelectric applications.

Polythiophene

Side chain

Charge density

10.1021/acs.chemmater.3c01680

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Solubilizing Benzodifuranone-Based Conjugated Copolymers with Single-Oxygen-Containing Branched Side Chains

ACS Applied Polymer Materials (2023)

Diego R. Hinojosa Nathan Pataki James Pietro Rossi Andreas Erhardt Shubhradip Guchait

Single-oxygen-containing branched side chains are designed and used to solubilize n-type copolymers consisting of BDF (benzodifuranone), isatin, and thiophene-based units. We present a simple synthetic approach to side chains with varying linker distances between the backbone and the branching point. The synthetic pathway is straightforward and modular and starts with commercially available reagents. The side chains give rise to excellent solubilities of BDF-thiophene copolymers of up to 90 mg/mL, while still being moderate in size (26–34 atoms large). The excellent solubility furthermore allows high molar mass materials. BDF-thiophene copolymers are characterized in terms of optoelectronic and thermoelectric properties. The electrical conductivity of chemically doped polymers is found to scale with molar mass, reaching ∼1 S/cm for the highest molar mass and longest backbone-branching point distance.

Side chain

Molar mass

Branching (polymer chemistry)

10.1021/acsapm.3c02137

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Spontaneous Modulation Doping in Semi‐Crystalline Conjugated Polymers Leads to High Conductivity at Low Doping Concentration

Advanced Materials (2023)

Aditya Dash Shubhradip Guchait Dorothea Scheunemann Vishnu Vijayakumar Nicolas Leclerc

The possibility to control the charge carrier density through doping is one of the defining properties of semiconductors. For organic semiconductors, the doping process is known to come with several problems associated with the dopant compromising the charge carrier mobility by deteriorating the host morphology and/or introducing Coulomb traps. While for inorganic semiconductors these factors can be mitigated through (top-down) modulation doping, this concept has not been employed in organics. Here, this work shows that properly chosen host/dopant combinations can give rise to spontaneous, bottom-up modulation doping, in which the dopants preferentially sit in an amorphous phase, while the actual charge transport occurs predominantly in a crystalline phase with an unaltered microstructure, spatially separating dopants and mobile charges. Combining experiments and numerical simulations, this work shows that this leads to exceptionally high conductivities at relatively low dopant concentrations.

Charge carrier

Organic semiconductor

10.1002/adma.202311303

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Citations (11)

Phase‐Selective Doping of Oriented Regioregular Poly(3‐hexylthiophene‐2,5‐diyl) Controls Stability of Thermoelectric Properties

Advanced Functional Materials (2024)

Shubhradip Guchait Aditya Dash Antoine Lemaire Laurent Herrmann Martijn Kemerink

Abstract This study focuses on the impact of dopant location in the semicrystalline structure of regioregular poly(3‐hexylthiophene‐2,5‐diyl) on the long‐term stability of thermoelectric properties probed in rub‐aligned films. Phase‐selective doping is possible by suitable choice of dopants. Anion exchange doping results in TFSI dopants located in both crystalline and amorphous domains whereas magic blue dopants are located in the amorphous phase only. The combination of rub‐alignment, increasing concentration doping, and anion exchange doping is effective to produce doped P3HT films with enhanced thermoelectric properties and stability. Transmission electron microscopy, polarized optical absorption spectroscopy, and transport measurements help identify different regimes of doping: crystalline domains are doped first by exchange of F 4 TCNQ − with TFSI − , followed by a progressive doping of amorphous regions. The best thermoelectric performances of TFSI‐exchanged P3HT lead to power factors in the 160–170 µW m −1 K −2 range. Despite similar TE performances, MB‐doped and TFSI‐exchanged P3HT films behave very differently on aging. Numerically exact kinetic Monte Carlo simulations clarify the origin of this difference. The retention of charges in any phase is crucial for the stability in conductivity, but the conductivity at long aging times, σ ∞ is quantitatively determined by the specific phase retaining the charges.

10.1002/adfm.202404411

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Citations (1)

Impact of the dopant location in the semi-crystalline structure of alternated donor–acceptor copolymers on the polarity switching p → n mechanism

Journal of Materials Chemistry C (2023)

Bharath Dyaga Antoine Lemaire Shubhradip Guchait Huiyan Zeng Bruno Schmaltz

The location of dopants in the crystalline and/or amorphous domains of D–A polymers determines the polarity switching of the Seebeck coefficient.

Polarity (international relations)

Acceptor

10.1039/d3tc02416d

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Citations (3)

Preferential Location of Dopants in the Amorphous Phase of Oriented Regioregular Poly(3‐hexylthiophene‐2,5‐diyl) Films Helps Reach Charge Conductivities of 3000 S cm⁻¹

Advanced Functional Materials (2022)

Yuhan Zhong Viktoriia Untilova D. Müller Shubhradip Guchait Céline Kiefer

Abstract Doping polymer semiconductors is a central topic in plastic electronics and especially in the design of novel thermoelectric (TE) materials. In this contribution, it has been demonstrated that doping of oriented semicrystalline P3HT thin films with the dopant tris(4‐bromophenyl)ammoniumyl hexachloroantimonate), known as magic blue (MB), helps reach charge conductivities of 3000 S cm −1 and TE power factors of 170 ± 30 μW mK −2 along the polymer chain direction. A combination of transmission electron microscopy, polarized optical absorption spectroscopy, Rutherford backscattering, and TE property measurements helps clarify the conditions necessary to achieve such high charge conductivities. A comparative study with different dopants demonstrates that the doping mechanism is intimately related to the semicrystalline structure of the polymer and whether crystalline, amorphous or both phases are doped. The highest charge mobilities are observed when the dopant MB is preferentially located in the amorphous phase of P3HT, leaving the structure of P3HT nanocrystals almost unaltered. In this case, the P3HT nanocrystals are doped from their interface with the surrounding amorphous phase. These results indicate that doping preferentially the amorphous phase of semicrystalline polymer semiconductors is an effective strategy to reduce polaron localization, enhance charge mobilities, and improve TE power factors.

Charge carrier

10.1002/adfm.202202075

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Citations (66)