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Physicochemical Properties of Organic and Hybrid Semiconductor Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Electronic Materials".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 12246

Special Issue Editor


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Guest Editor
Tokyo University of Science, Tokyo, Japan
Interests: organic semiconductor; electronic structure; photoelectron spectroscopy; surface science

Special Issue Information

Dear Colleagues,

Whereas semiconductor electronics in the 20th century were almost invariably functionalized by inorganic materials such as silicon, organic and organic–inorganic–hybrid semiconductor materials have been brought to the front stage of electronics technologies through rapid-paced development in the recent couple of decades; wide-spread commercialization of organic light emitting diodes (OLEDs) as full-color display devices is one representation of their success, and recent enthusiastic interest in organic–inorganic–hybrid “perovskites” for opto-electronic applications is another prominent example. Despite such remarkable progress in the application side, however, there are still plenty of questions unsolved about fundamental physics and chemistry behind the working devices.

In this Special Issue, we are calling for original and review papers regarding “Physicochemical Properties of Organic and Hybrid Semiconductor Materials” in a broad sense. Not only literally organic semiconductors (including polymeric semiconductors) but also “hybrid” materials in any sense, such as organic–inorganic, metal–organic, bio-inspired, and so on, are within the scope of this Special Issue as long as these exhibit (or are expected to exhibit) semiconductor characteristics. Any fundamental properties of these materials lying behind fabrication and operation processes of the electronic devices, e.g., crystallization, epitaxial growth, electronic (band) structures, and charge carrier transport mechanisms, are covered in the range of the topics. We are looking for contributions on theoretical approaches to these topics as well as experimental works.

Prof. Yasuo Nakayama
Guest Editor

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Keywords

  • organic (opto-)electronics
  • emerging materials for flexible devices
  • bioelectronics
  • superconductivity
  • charge carrier transport
  • electronic (band) structures
  • quasi-particle properties (polaron/exciton/phonon/vibron)
  • doping/charge transfer
  • crystal growth/epitaxy
  • state-of-the-art methodologies for materials properties

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Published Papers (4 papers)

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Research

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9 pages, 3798 KiB  
Article
Improved Electrical Characteristics of Gallium Oxide/P-Epi Silicon Carbide Static Induction Transistors with UV/Ozone Treatment Fabricated by RF Sputter
by Myeong-Cheol Shin, Young-Jae Lee, Dong-Hyeon Kim, Seung-Woo Jung, Michael A. Schweitz, Weon Ho Shin, Jong-Min Oh, Chulhwan Park and Sang-Mo Koo
Materials 2021, 14(5), 1296; https://doi.org/10.3390/ma14051296 - 8 Mar 2021
Cited by 5 | Viewed by 3050
Abstract
In this study, static induction transistors (SITs) with beta gallium oxide (β-Ga2O3) channels are grown on a p-epi silicon carbide (SiC) layer via radio frequency sputtering. The Ga2O3 films are subjected to UV/ozone treatment, which results [...] Read more.
In this study, static induction transistors (SITs) with beta gallium oxide (β-Ga2O3) channels are grown on a p-epi silicon carbide (SiC) layer via radio frequency sputtering. The Ga2O3 films are subjected to UV/ozone treatment, which results in reduced oxygen vacancies in the X-ray photoelectron spectroscopy data, lower surface roughness (3.51 nm) and resistivity (319 Ω·cm), and higher mobility (4.01 cm2V−1s−1). The gate leakage current is as low as 1.0 × 10−11 A at VGS = 10 V by the depletion layer formed between n-Ga2O3 and p-epi SiC at the gate region with a PN heterojunction. The UV/O3-treated SITs exhibit higher (approximately 1.64 × 102 times) drain current (VDS = 12 V) and on/off ratio (4.32 × 105) than non-treated control devices. Full article
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10 pages, 3129 KiB  
Article
Interface Structures and Electronic States of Epitaxial Tetraazanaphthacene on Single-Crystal Pentacene
by Yuki Gunjo, Hajime Kamebuchi, Ryohei Tsuruta, Masaki Iwashita, Kana Takahashi, Riku Takeuchi, Kaname Kanai, Tomoyuki Koganezawa, Kazuhiko Mase, Makoto Tadokoro and Yasuo Nakayama
Materials 2021, 14(5), 1088; https://doi.org/10.3390/ma14051088 - 26 Feb 2021
Cited by 7 | Viewed by 2683
Abstract
The structural and electronic properties of interfaces composed of donor and acceptor molecules play important roles in the development of organic opto-electronic devices. Epitaxial growth of organic semiconductor molecules offers a possibility to control the interfacial structures and to explore precise properties at [...] Read more.
The structural and electronic properties of interfaces composed of donor and acceptor molecules play important roles in the development of organic opto-electronic devices. Epitaxial growth of organic semiconductor molecules offers a possibility to control the interfacial structures and to explore precise properties at the intermolecular contacts. 5,6,11,12-tetraazanaphthacene (TANC) is an acceptor molecule with a molecular structure similar to that of pentacene, a representative donor material, and thus, good compatibility with pentacene is expected. In this study, the physicochemical properties of the molecular interface between TANC and pentacene single crystal (PnSC) substrates were analyzed by atomic force microscopy, grazing-incidence X-ray diffraction (GIXD), and photoelectron spectroscopy. GIXD revealed that TANC molecules assemble into epitaxial overlayers of the (010) oriented crystallites by aligning an axis where the side edges of the molecules face each other along the [1¯10] direction of the PnSC. No apparent interface dipole was found, and the energy level offset between the highest occupied molecular orbitals of TANC and the PnSC was determined to be 1.75 eV, which led to a charge transfer gap width of 0.7 eV at the interface. Full article
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12 pages, 3952 KiB  
Article
Excited-State Dynamics of Room-Temperature Phosphorescent Organic Materials Based on Monobenzil and Bisbenzil Frameworks
by Kaveendra Maduwantha, Shigeyuki Yamada, Kaveenga Rasika Koswattage, Tsutomu Konno and Takuya Hosokai
Materials 2020, 13(17), 3904; https://doi.org/10.3390/ma13173904 - 3 Sep 2020
Cited by 1 | Viewed by 3292
Abstract
Room-temperature phosphorescent (RTP) materials have been attracting tremendous interest, owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we reported the synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and [...] Read more.
Room-temperature phosphorescent (RTP) materials have been attracting tremendous interest, owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we reported the synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and fluorinated and non-fluorinated bisbenzil derivative analogues [Yamada, S. et al., Beilstein J. Org. Chem. 2020, 16, 1154–1162.]. To deeply understand their RTP properties, we investigated the excited-state dynamics and photostability of the derivatives by means of time-resolved and steady-state photoluminescence spectroscopies. For these derivatives, clear RTP emissions with lifetimes on the microsecond timescale were identified. Among them, the monobenzil derivative was found to be the most efficient RTP material, showing both the longest lifetime and highest amplitude RTP emission. Time-resolved photoluminescence spectra, measured at 77 K, and density functional theory calculations revealed the existence of a second excited triplet state in the vicinity of the first excited singlet state for the monobenzil derivative, indicative of the presence of a fast intersystem crossing pathway. The correlation between the excited state dynamics, emission properties, and conformational flexibility of the three derivatives is discussed. Full article
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Review

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24 pages, 7885 KiB  
Review
‘Molecular Beam Epitaxy’ on Organic Semiconductor Single Crystals: Characterization of Well-Defined Molecular Interfaces by Synchrotron Radiation X-ray Diffraction Techniques
by Yasuo Nakayama, Ryohei Tsuruta and Tomoyuki Koganezawa
Materials 2022, 15(20), 7119; https://doi.org/10.3390/ma15207119 - 13 Oct 2022
Cited by 7 | Viewed by 2481
Abstract
Epitaxial growth, often termed “epitaxy”, is one of the most essential techniques underpinning semiconductor electronics, because crystallinities of the materials seriously dominate operation efficiencies of the electronic devices such as power gain/consumption, response speed, heat loss, and so on. In contrast to already [...] Read more.
Epitaxial growth, often termed “epitaxy”, is one of the most essential techniques underpinning semiconductor electronics, because crystallinities of the materials seriously dominate operation efficiencies of the electronic devices such as power gain/consumption, response speed, heat loss, and so on. In contrast to already well-established epitaxial growth methodologies for inorganic (covalent or ionic) semiconductors, studies on inter-molecular (van der Waals) epitaxy for organic semiconductors is still in the initial stage. In the present review paper, we briefly summarize recent works on the epitaxial inter-molecular junctions built on organic semiconductor single-crystal surfaces, particularly on single crystals of pentacene and rubrene. Experimental methodologies applicable for the determination of crystal structures of such organic single-crystal-based molecular junctions are also illustrated. Full article
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