Hall Effect in Bulk‐Doped Organic Single Crystals

Ohashi, Chika; Izawa, Seiichiro; Shinmura, Yusuke; Kikuchi, Masatoshi; Watase, Seiji; Izaki, Masanobu; Naito, Hiroyoshi; Hiramoto, Masahiro

doi:10.1002/adma.201605619

Cited by 27 publications

(50 citation statements)

References 26 publications

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“…Doping is generally conducted on polycrystalline thin films, but Masahiro Hiramoto and co‐workers have succeeded to grow single crystals of rubrene 3 doped with minute amounts of FeCl 3 . The highest charge carrier mobility ( µ = 4.6 cm 2 V −1 s −1 ), measured by Hall effect, has been achieved at only 10 ppm of dopant …”

Section: Charge Transportmentioning

confidence: 97%

“…Dopant density also determines doping efficiency because additional ionized dopants favor charge separation . It must be stressed that the open question of doping efficiency cannot be treated completely apart from those of molecular structures, miscibility, morphology, defects, impurities (notably water and oxygen), and device stability . Charge transport within doped organic semiconductors is thermally activated.…”

Section: Charge Transportmentioning

confidence: 99%

“…One can conclude from this short discussion that a plethora of electronic situations occur or even coexist depending on semiconductor‐dopant pairs, temperature, film thickness, and sample preparation conditions . Structural and morphological control upon doping polycrystalline or single crystal thin films of molecular semiconductors is particularly challenging, although not so often considered . Most doping studies call upon spectroscopic and electrical measurements.…”

Section: Charge Transportmentioning

confidence: 99%

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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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Section: Charge Transportmentioning

confidence: 97%

Section: Charge Transportmentioning

confidence: 99%

Section: Charge Transportmentioning

confidence: 99%

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

et al. 2020

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“…[35,36] It is also noteworthy that the present Pn-SC substrates experienced exposure to the ambient air and light, and it is known that a few percent of oxides are generated at the Pn-SC surface by ambient exposure. Another strategy may be the suppression of factors hindering the surface diffusion.…”

Section: Wwwadvmatinterfacesdementioning

confidence: 99%

Temperature Dependent Epitaxial Growth of C₆₀ Overlayers on Single Crystal Pentacene

Nakayama

Tsuruta

Hinderhofer

et al. 2018

Adv Materials Inter

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due to charge carrier delocalization. [10][11][12][13][14] Accordingly, accurate control of the crystal quality of molecular heterojunctions is desired for advancing further development of next-generation organic electronic devices. [15][16][17] In the present work, the evolution of the crystallinity of a well-ordered bimolecular heterojunction, C 60 on a single crystal surface of pentacene (C 22 H 14 ), is studied depending on the growth temperature by means of surface X-ray diffraction techniques and noncontact mode atomic force microscopy (nc-AFM). Pentacene ( Figure 1a) and C 60 ( Figure 1b) are representative p-type (donor) and n-type (acceptor) semiconducting compounds generating an exciton-dissociating interface in a prototypical organic solar cell device. [18] The pentacene/C 60 interface has been studied widely, both experimentally [19][20][21][22][23][24] and theoretically. [25][26][27][28][29][30] It was recently discovered that C 60 crystallizes in its bulk structure epitaxially by aligning the nearest-neighbor face-centered-cubic (fcc)-110 < > axis uniquely along the [110] direction of the pentacene single crystal (Pn-SC) surface. [31] The type of this epitaxial interface is categorized into the incommensurism, whereas it is nearly of so-called "Type-IB" point-on-line coincidence [32] with a 6% lattice mismatch, as illustrated in Figure 1c. Moreover, the crystallographic coherence length of the C 60 overlayers grown at room temperature (RT) was found to exceed 100 nm in the in-plane directions. [33] The well-defined interface between Pn-SC and C 60 is ideally suited to study kinetic effects [34] in the growth of the topical donor-acceptor heterojunction. We herein demonstrate the crystallographic coherence of the C 60 overlayers on the Pn-SC as a function of the growth temperature through systematic Heteroepitaxy of one material onto another molecular single crystal surface is one promising route for resolving questions about formation criteria of molecular heterojunction structures as well as for the development of nextgeneration organic electronic devices allowing efficient intermolecular charge carrier exchange. In the present work, the in-plane and out-of-plane crystallinity of an epitaxial molecular p-n heterojunction, C 60 (acceptor) overlayers formed on the single crystal surface of pentacene (donor), and its evolution, depending on the growth temperature, are systematically elucidated. It is demonstrated that the crystallinity of the C 60 on pentacene is dominated by the temperature during the growth rather than the postannealing of the sample. The mean crystallite size in the in-plane directions grows from 50 to 150 nm proportionally to the growth temperature in a range of 125-370 K. The present results suggest that the formation mechanisms of the C 60 /pentacene heterojunction are kinetically controlled, by diffusion processes at the molecular interface, rather than by the thermal equilibrium conditions.

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“…Recently, even an extremely small amount of dopant reaching the ppm level was revealed to affect the electrical characteristics of OSC films and organic single crystals . Some papers reported significantly higher doping efficiency .…”

Section: Introductionmentioning

confidence: 99%

Parts‐per‐Million‐Level Doping Effects in Organic Semiconductor Films and Organic Single Crystals

2018

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Controlling the pn-type behavior of a semiconductor such as silicon by adding an extremely small quantity of an impurity (doping) is a central part of inorganic semiconductor electronics since the 20th century. Recent progress in the doping of organic semiconductors strongly suggests the advent of a new era of doped organic semiconductors. Here, the principles and effects of doping at the level of parts per million (ppm) in organic semiconductor films and single crystals are described, including descriptions of complete pn-control, doping sensitization, ppm doping using an extremely low-speed deposition technique reaching 10 nm s , and emerging ppm-level doping effects, such as trap filling, majority carriers, homojunction formation, and decreased mobility, as well as ppm-level doping effects in organic single crystals measured by the Hall effect, which shows a doping efficiency of 24%. The Wannier excitonic doping of organic single crystals possessing band conduction and the defect science of organic single crystals related to carrier trapping and scattering are introduced as a new scientific field. The dawn of organic single-crystal electronics is also discussed.

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Hall Effect in Bulk‐Doped Organic Single Crystals

Cited by 27 publications

References 26 publications

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

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

Temperature Dependent Epitaxial Growth of C₆₀ Overlayers on Single Crystal Pentacene

Parts‐per‐Million‐Level Doping Effects in Organic Semiconductor Films and Organic Single Crystals

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Hall Effect in Bulk‐Doped Organic Single Crystals

Cited by 27 publications

References 26 publications

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

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

Temperature Dependent Epitaxial Growth of C60 Overlayers on Single Crystal Pentacene

Parts‐per‐Million‐Level Doping Effects in Organic Semiconductor Films and Organic Single Crystals

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Temperature Dependent Epitaxial Growth of C₆₀ Overlayers on Single Crystal Pentacene