A map of high-mobility molecular semiconductors

Fratini, Simone; Ciuchi, S.; Mayou, Didier; Laissardière, Guy Trambly de; Troisi, Alessandro

doi:10.1038/nmat4970

Cited by 221 publications

(397 citation statements)

References 36 publications

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“…Given that the charge transfer integral decreases exponentially with the π–π stacking distance, we show that greater lattice disorder leads to a higher mean charge transfer integral and faster charge transport in the π–π stacking direction. Although charge hopping models may not be applicable to high‐performance small molecules and polymers, for which the charge mobilities exceed 1 cm 2 V −1 s −1 with band‐like power‐law temperature dependences, our results nevertheless highlight the potential for thermal fluctuations in these systems to create strongly coupled regions that promote delocalization and result in high‐mobility pathways …”

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confidence: 77%

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Thermal Fluctuations Lead to Cumulative Disorder and Enhance Charge Transport in Conjugated Polymers

Zhang

Bombile

Weisen

et al. 2019

Macromol. Rapid Commun.

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All conjugated polymers examined to date exhibit significant cumulative lattice disorder, although the origin of this disorder remains unclear. Using atomistic molecular dynamics (MD) simulations, the detailed structures for single crystals of a commonly studied conjugated polymer, poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) are obtained. It is shown that thermal fluctuations of thiophene rings lead to cumulative disorder of the lattice with an effective paracrystallinity of about 0.05 in the π–π stacking direction. The thermal‐fluctuation‐induced lattice disorder can in turn limit the apparent coherence length that can be observed in diffraction experiments. Calculating mobilities from simulated crystal structures demonstrates that thermal‐fluctuation‐induced lattice disorder even enhances charge transport in P3HT. The mean inter‐chain charge transfer integral is enhanced with increasing cumulative lattice disorder, which in turn leads to pathways for fast charge transport through crystals.

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confidence: 77%

“…Local order is critical to the performance of organic semiconductors. Conformational and configurational disorder can affect charge delocalization, and in turn lead to localized trap states in these materials . Although small conjugated molecules can be well‐ordered, many conjugated polymers exhibit significant disorder.…”

mentioning

confidence: 99%

Thermal Fluctuations Lead to Cumulative Disorder and Enhance Charge Transport in Conjugated Polymers

Zhang

Bombile

Weisen

et al. 2019

Macromol. Rapid Commun.

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“…The crucial point is that J ≈ λ in organic solids, highlighting the need to develop a theory for this crossover regime. Although not unique, a new model taking into account the key characteristics of molecular solids has been implemented in the recent years to describe the intermediate regime of charge transport present in molecular organic semiconductors, the transient localization scenario . In this model, the phonon modes (thermal lattice fluctuations) cause temporal variations in the transfer integrals and site energies across the molecular lattice .…”

Section: Charge Transportmentioning

confidence: 99%

“…On one hand, this change of paradigm in terms of fabrication of electronic circuits was evidently attractive. On the other hand, there was also considerable place for improvements of organic semiconductors thanks to quantum chemistry that helps the establishment of design rules and to synthetic chemistry that gives access to a nearly infinite number of molecular structures . The field of organic semiconductors for logic operations has witnessed an impressive development.…”

Section: Introductionmentioning

confidence: 99%

Molecular Semiconductors for Logic Operations: Dead‐End or Bright Future?

et al. 2020

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The field of organic electronics has been prolific in the last couple of years, leading to the design and synthesis of several molecular semiconductors presenting a mobility in excess of 10 cm2 V−1 s−1. However, it is also started to recently falter, as a result of doubtful mobility extractions and reduced industrial interest. This critical review addresses the community of chemists and materials scientists to share with it a critical analysis of the best performing molecular semiconductors and of the inherent charge transport physics that takes place in them. The goal is to inspire chemists and materials scientists and to give them hope that the field of molecular semiconductors for logic operations is not engaged into a dead end. To the contrary, it offers plenty of research opportunities in materials chemistry.

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“…The charge transport in organic crystals cannot be adequately described by either purely bandlike/ coherent transport, nor by hopping transport. [138,139] [135,136] In contrast to amorphous semiconductor materials, in high-quality crystalline organic solids, the structural (static) disorder is small and the fluctuation of intermolecular transfer integrals (dynamic disorder) remains the factor that intrinsically limits the mobility.…”

Section: Mesoscalementioning

confidence: 99%

Toward Design of Novel Materials for Organic Electronics

et al. 2019

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organic/inorganic perovskites solar cells [6] to printable electronic circuits based on organic field-effect transistors (OFETs). [7] While OLED displays outperform their inorganic counterparts in terms of energy efficiency, [8] scientific and technical challenges concerning the stability and processability of the organic materials used in large-area OLEDs and organic solar cells remain. New challenges arise from applications, such as displays on flexible substrates, OLED lightning, large area displays as well as for printable or solution processable larger area solar cells. [8] Many of the remaining challenges are material related, e.g., the low mobility of charge carriers in organic materials in general and in amorphous organic semiconductors in particular. There are other materials related issues, such as limited OLED life times due to unstable blue hosts and emitters, [9] low fill factors, and therefore reduced power conversion efficiencies of organic solar cells, [10,11] low conductivity and high costs of organic charge transport layers of perovskite solar cells [6,12,13] and low conductivity and hard processability of crystalline OFET materials. [14] Conductivity and injection can be improved by doping the organic thin films with molecular dopants with high electron affinities (p-type) [15] or low ionization energies (n-type). [16] The doping mechanism of organic materials is in many cases not well understood, [17] making material and device optimization a costly experimental endeavor.The development of better materials is presently based on chemical insight, in part guided by theoretical understanding, or the experimental screening of large numbers of compounds. Given the size of the potentially available chemical space this remains a costly and time-consuming approach. Recent successes in experimental design of novel materials and concepts include the development of a stable strong molecular n-type dopant, [16] a study about the quantitative relation between interaction parameter, miscibility, and function of conjugated polymer donors and small-molecule acceptors for bulk heterojunctions as used in organic solar cells [18] the development of a universal strategy for ohmic hole injection into organic semiconductors with high ionization energies [19] and many others. [20][21][22][23][24][25] Another example is the development of strategies to harvest triplet excitons in organic light emitting diodes. For this purpose, novel classes of emitter molecules were developed, which include thermally activated delayed fluorescence (TADF)-based molecules, [26][27][28][29][30][31][32] rotationally accessed spin-state inversion, [33] and radical-based emitters. [34] Materials for organic electronics are presently used in prominent applications, such as displays in mobile devices, while being intensely researched for other purposes, such as organic photovoltaics, large-area devices, and thin-film transistors. Many of the challenges to improve and optimize these applications are material related and there is a nearly inf...

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A map of high-mobility molecular semiconductors

Cited by 221 publications

References 36 publications

Thermal Fluctuations Lead to Cumulative Disorder and Enhance Charge Transport in Conjugated Polymers

Thermal Fluctuations Lead to Cumulative Disorder and Enhance Charge Transport in Conjugated Polymers

Molecular Semiconductors for Logic Operations: Dead‐End or Bright Future?

Toward Design of Novel Materials for Organic Electronics

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