Reactivity of an air-stable dihydrobenzoimidazole n-dopant with organic semiconductor molecules

Jhulki, Samik; Un, Hio‐Ieng; Ding, Yifan; Risko, Chad; Mohapatra, Swagat K.; Pei, Jian; Barlow, Stephen; Marder, Seth R.

doi:10.1016/j.chempr.2021.01.020

Cited by 52 publications

(105 citation statements)

References 49 publications

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“…20 Additionally, introducing low amounts of a dopant can increase the charge-carrier mobility in the OSC. 21 There are two primary doping methods, including chemical doping, which can occur through a number of different mechanisms (e.g., acid doping, 22 oxidative doping, 15,23 hydride transfer, 24,25 etc.) and electrochemical doping.…”

Section: Introductionmentioning

confidence: 99%

Impact of the anion on electrochemically doped regioregular and regiorandom poly(3‐hexylthiophene)

Baustert

Abtahi

Ayyash

et al. 2021

Journal of Polymer Science

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Chemical and electrochemical doping of π-conjugated polymers is an important aspect in determining the performance and enabling the operation of many organic electronic devices, from organic light emitting diodes and thermoelectrics to organic electrochemical transistors. In both chemical doping and electrochemical doping an ionized dopant or counterion is present along with the doped π-conjugated polymer. This dopant or counterion is not a benign spectator, rather, its presence can significantly impact the optical, electronic, and thermoelectric properties of the resulting material. Here, we investigate how counterion structure impacts the electrochemical doping ability, oxidation potential, ionization energy, and polaron absorbance of regioregular (rr) and regiorandom (rra) P3HT. We find that in most cases the anion has a small effect on the polymer oxidation potential, except for in the case of rr-P3HT with the large tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion. We propose that this large anion is excluded from the crystalline regions and thus the oxidation potential is similar to that of rra-P3HT. The anions also result in significant differences in polaron absorbance and ionization energies, thereby emphasizing the important role of the counterion in determining the optical and electronic properties of doped π-conjugated polymers.

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Section: Introductionmentioning

confidence: 99%

Impact of the anion on electrochemically doped regioregular and regiorandom poly(3‐hexylthiophene)

Baustert

Abtahi

Ayyash

et al. 2021

Journal of Polymer Science

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“…In the future, more efforts need to be devoted to the following: (1) The n-doping mechanism . In the most n-doped polymer systems, the doping mechanism is still unclear, which severely limits the new materials design and the control of n-doping process. − (2) The aggregation behaviors of conjugated polymers in solution . Most n-doping processes occur in solution, but the effects of aggregation behavior of intrinsic or doped polymers on n-doping efficiency are usually ignored .…”

Section: Conclusion and Outlookmentioning

confidence: 99%

Achieving Efficient n-Doping of Conjugated Polymers by Molecular Dopants

2021

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Metrics & MoreArticle Recommendations CONSPECTUS: Molecular doping is one of the most central propositions in the field of organic electronics. Unlike classical inorganic semiconductors doped by atomic substitution, organic conjugated materials react with molecular dopants, and then intermolecular charge transfer is involved within. Therefore, the complex noncovalent interactions between two components often cause the molecular dopant to destroy the orderly stacking of the host organic materials and reduce the original properties of the material, such as carrier mobility, which here we call the "doping dilemma." Recently, many studies focus on improving p-doping efficiency and electrical conductivity of doped conjugated polymers; however, the development of n-type molecular doping currently lags far behind that of its p-counterpart. It is well-known that both efficient p-and n-type molecular doping are indispensable in various organic electronic devices, including light-emitting diodes, photovoltaics, field-effect transistors, and thermoelectrics. It is thus an urgent requirement to achieve efficient n-doping in conjugated polymers.In this Account, we give a brief overview of our efforts to improve the n-doping efficiency in conjugated polymers with several strategies from the aspects of the polymer/dopant molecular design and the exploration of the ntype molecular doping mechanism and charge transport mechanism in n-doped organic materials. For the conjugated polymer engineering, we first demonstrate that increasing the electron affinity of the host polymer through halogen substitution can boost the n-doping efficiency. Still, the rigid coplanar backbones of conjugated polymers play a crucial role in the polaron delocalization and final electrical performance. In addition, we emphasize the importance of morphology control in the doped polymers to address the "doping dilemma." For n-dopants designing, we summarize some basic guidelines from molecular sizes and shapes, the interaction between dopants (or dopant cations) and polymers, and the effects of dopants on morphology to design high-efficacy n-type molecular dopants. We propose that the polymers and the dopants need to be treated as a whole system; while enhancing the ionization efficiency, more attention should be paid to the carrierization (free-carrier generation) efficiency of these binary systems.In the end, we adopt the n-type polymer thermoelectric material as an example to discuss the grand challenges encountered in practical applications of n-doped conjugated polymers. The air stability and micrometer-thick thermo-leg processing of n-doped polymers are highlighted for thermoelectric applications. It is our hope that this Account showcases a blueprint for rational approaches and a deep understanding toward the design and development of efficient n-doping in conjugated polymers, bringing ndoped organic materials into the next era.

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“…However, there has been outstanding progress in recent years that has been able to address these issues to a great extent, and practical strategies have been proposed for both p- and n-type doping with numerous articles and reviews of the area. 45 − 49 For instance, exposing the pentacene films to iodine vapor is shown to be among the practical methods that leads to high mobility and conductivity, implying that the crystal structure remains undisturbed even at higher doping concentrations. 50 The X-ray diffraction (XRD) evaluation of iodine doped pentacene has shown that iodine gets essentially intercalated between the planes of pentacene, meaning that the in-plane herringbone structure remains intact.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of p-Doped Molecular Crystals as Transparent Conductive Electrodes via Virtual Screening

Nematiaram

Troisi

2022

Chem. Mater.

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Transparent conducting materials are an essential component of optoelectronic devices. It is proven difficult, however, to develop high-performance materials that combine the often-incompatible properties of transparency and conductivity, especially for p-type-doped materials. In this work, we have employed a large set of molecular semiconductors extracted from the Cambridge Structural Database to evaluate the likelihood of transparent conducting material technology based on p-type-doped molecular crystals. Candidates are identified imposing the condition of high highest occupied molecular orbital (HOMO) energy level (for the material to be easily dopable), high charge carrier mobility (for the material to display large conductivity when doped), and a high threshold for energy absorption (for the material to absorb radiation only in the ultraviolet). The latest condition is found to be the most stringent criterion in a virtual screening protocol on a database composed of structures with sufficiently wide two-dimensional (2D) electronic bands. Calculation of excited-state energy is shown to be essential as the HOMO–lowest unoccupied molecular orbital (LUMO) gap cannot be reliably used to predict the transparency of this material class. Molecular semiconductors with desirable mobility are transparent because they display either forbidden electronic transition(s) to the lower excited states or small exchange energy between the frontier orbitals. Both features are difficult to design but can be found in a good number of compounds through virtual screening.

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Reactivity of an air-stable dihydrobenzoimidazole n-dopant with organic semiconductor molecules

Cited by 52 publications

References 49 publications

Impact of the anion on electrochemically doped regioregular and regiorandom poly(3‐hexylthiophene)

Impact of the anion on electrochemically doped regioregular and regiorandom poly(3‐hexylthiophene)

Achieving Efficient n-Doping of Conjugated Polymers by Molecular Dopants

Feasibility of p-Doped Molecular Crystals as Transparent Conductive Electrodes via Virtual Screening

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