High Conductivity in Molecularly p‐Doped Diketopyrrolopyrrole‐Based Polymer: The Impact of a High Dopant Strength and Good Structural Order

Karpov, Yevhen; Erdmann, Tim; Raguzin, Ivan; Al‐Hussein, Mahmoud; Binner, Marcus; Lappan, Uwe; Stamm, Manfred; Gerasimov, Kirill L.; Beryozkina, Tetyana; Бакулев, В. А.; Anokhin, Denis V.; Ivanov, Dimitri A.; Günther, Florian; Gemming, Sibylle; Seifert, Gotthard; Voit, Brigitte; Pietro, Riccardo Di; Kiriy, Anton

doi:10.1002/adma.201506295

Cited by 149 publications

(190 citation statements)

References 40 publications

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“…A general observation is that, while the ICT takes place in all the complexes containing CN6-CP and/or the heptamer (regardless of the position of the dopant) it is not always found in the other complexes. This finding confirms earlier findings [30] where CN6-CP was identified as the strongest molecular dopant among the series of dopants studied in the present work. Although alignment of single-particle energy levels is recognized not to be the only driving factor for ICT to occur [20], the strong doping strength of CN6-CP is also reflected by its lower LUMO level [27] than those of F4TCNQ and F6TCNNQ.…”

Section: Resultssupporting

confidence: 94%

Molecular Doping of PCPDT-BT Copolymers: Comparison of Molecular Complexes with and Without Integer Charge Transfer

Dong¹,

Schumacher²

2019

Preprint

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Molecular doping in conjugated polymers is a crucial process for their application in organic photovoltaics and optoelectronics. In the present work we theoretically investigate p-type molecular doping in a series of (poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b"]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDT-BT) conjugated oligomers with different lengths and three widely-used dopants with different electron affinities, namely F4TCNQ, F6TCNNQ, and CN6-CP. We study in detail the molecular geometry of possible oligomer-dopant complexes and its influence on the doping mechanisms and electronic system properties. We find that the mechanisms of doping and charge transfer observed sensitively depend on the specific geometry of the oligomer-dopant complexes. For a given complex different geometries may exist, some of which show transfer of an entire electron from the oligomer chain onto the dopant molecule resulting in an integer-charge transfer complex, leaving the system in a ground state with broken spin symmetry. In other geometries merely hybridization of oligomer and dopant frontier orbitals occurs with partial charge transfer but spin-symmetric ground state. Considering the resulting electronic density of states both cases may well contribute to an increased electrical conductivity of corresponding film samples while the underlying physical mechanisms are entirely different.

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Section: Resultssupporting

confidence: 94%

Molecular Doping of PCPDT-BT Copolymers: Comparison of Molecular Complexes with and Without Integer Charge Transfer

Dong¹,

Schumacher²

2019

Preprint

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“…[ 36 ] For the chemical doping of DPP‐based donor–acceptor copolymers with IP >5.2 eV, specially designed dopants with large electron affinities (EA) are required to achieve a high degree of charging. [ 37 ] To properly quantify the relative likelihood of the oxidation reactions of the polymers, the thermodynamic driving forces could be worked out, for example, using DFT calculations [ 23,38 ] if the precise reaction mechanism were known. While the polyanion PSS − in PEDOT:PSS might affect the rate of oxidation, since it is known to be a good proton conductor, [ 39 ] we believe that the rapid oxidation of PEDOT:PSS arises from its high‐lying HOMO.…”

Section: Figurementioning

confidence: 99%

Energetic Control of Redox‐Active Polymers toward Safe Organic Bioelectronic Materials

et al. 2020

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Organic semiconductors with polar sidechains have been identified as a promising class of materials for the field of bioelectronics. These materials, also called organic mixed ionic/electronic conductors (OMIECs), can exchange ions with aqueous electrolytes when electronic charge carriers are injected, transported, and stored in the bulk of the material. [1] Recent developments of OMIECs based on redox-active conjugated polymers [2][3][4][5][6][7][8] and novel device concepts [9,10] have opened up new pathways for bioelectronic devices including integrated circuits for electroencephalogram (EEG) monitoring [9] or low-power voltage amplifiers based on organic electrochemical transistors (OECTs). [11] Specifically, the OECT has drawn significant attention in the field of organic bioelectronics. It operates by electrochemically modulating the conductivity of a redox-active channel material with an electrolyte that is often aqueous, Avoiding faradaic side reactions during the operation of electrochemical devices is important to enhance the device stability, to achieve low power consumption, and to prevent the formation of reactive side-products. This is particularly important for bioelectronic devices, which are designed to operate in biological systems. While redox-active materials based on conducting and semiconducting polymers represent an exciting class of materials for bioelectronic devices, they are susceptible to electrochemical side-reactions with molecular oxygen during device operation. Here, electrochemical side reactions with molecular oxygen are shown to occur during organic electrochemical transistor (OECT) operation using high-performance, state-of-the-art OECT materials. Depending on the choice of the active material, such reactions yield hydrogen peroxide (H 2 O 2 ), a reactive side-product, which may be harmful to the local biological environment and may also accelerate device degradation. A design strategy is reported for the development of redox-active organic semiconductors based on donor-acceptor copolymers that prevents the formation of H 2 O 2 during device operation. This study elucidates the previously overlooked side-reactions between redox-active conjugated polymers and molecular oxygen in electrochemical devices for bioelectronics, which is critical for the operation of electrolyte-gated devices in application-relevant environments.

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“…As an electron‐deficient building block with good molecular planarity and biodegradability, DPP is one of the most intensively studied building blocks of D–A polymers for thin film transistors and solar cells . DPP‐based polymers show a high p‐type electrical conductivity after p‐doping, but their n‐doping capability has been less studied. Thus, we designed and synthesized the DPP‐based polymer PDPF by introducing fluorine atoms on its donor moiety.…”

Section: Molecular Weights Pdi Optical Bandgaps and Energy Levelsa)mentioning

confidence: 99%

Enhancing the n‐Type Conductivity and Thermoelectric Performance of Donor–Acceptor Copolymers through Donor Engineering

et al. 2018

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Conjugated polymers with high thermoelectric performance enable the fabrication of low-cost, large-area, low-toxicity, and highly flexible thermoelectric devices. However, compared to their p-type counterparts, n-type polymer thermoelectric materials show much lower performance, which is largely due to inefficient doping and a much lower conductivity. Herein, it is reported that the development of a donor-acceptor (D-A) polymer with enhanced n-doping efficiency through donor engineering of the polymer backbone. Both a high n-type electrical conductivity of 1.30 S cm and an excellent power factor (PF) of 4.65 µW mK are obtained, which are the highest reported values among D-A polymers. The results of multiple characterization techniques indicate that electron-withdrawing modification of the donor units enhances the electron affinity of the polymer and changes the polymer packing orientation, leading to substantially improved miscibility and n-doping efficiency. Unlike previous studies in which improving the polymer-dopant miscibility typically resulted in lower mobilities, the strategy maintains the mobility of the polymer. All these factors lead to prominent enhancement of three orders magnitude in both the electrical conductivity and the PF compared to those of the non-engineered polymer. The results demonstrate that proper donor engineering can enhance the n-doping efficiency, electrical conductivity, and thermoelectric performance of D-A copolymers.

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High Conductivity in Molecularly p‐Doped Diketopyrrolopyrrole‐Based Polymer: The Impact of a High Dopant Strength and Good Structural Order

Cited by 149 publications

References 40 publications

Molecular Doping of PCPDT-BT Copolymers: Comparison of Molecular Complexes with and Without Integer Charge Transfer

Molecular Doping of PCPDT-BT Copolymers: Comparison of Molecular Complexes with and Without Integer Charge Transfer

Energetic Control of Redox‐Active Polymers toward Safe Organic Bioelectronic Materials

Enhancing the n‐Type Conductivity and Thermoelectric Performance of Donor–Acceptor Copolymers through Donor Engineering

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