Comparative Carrier Transport Characteristics in Organic Field‐Effect Transistors with Vapor‐Deposited Thin Films and Epitaxially Grown Crystals of Biphenyl‐Capped Thiophene Oligomers

Yanagi, Hisao; Araki, Younosuke; Ohara, Tomoya; Hotta, Shu; Ichikawa, M.; Taniguchi, Yoshiharu

doi:10.1002/adfm.200304418

Cited by 77 publications

(62 citation statements)

References 23 publications

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“…Similar fiberlike structures have been obtained by Yanagi et al [80,237,241] after vapour deposition of PPTTPP onto a cleaved ionic KCl (1 0 0) surface at elevated substrate temperatures. The green fluorescent fiberlike crystals epitaxially grow along the orthogonal 1 1 0 directions of the KCl substrate.…”

Section: Ppttppsupporting

confidence: 65%

“…Guided by this simple molecular design principle, these oligomers are predestinated to explore structure-property relationship for organic semiconductors. These phenyl-thiophene co-oligomers have attracted attention due to their potential as active components in OLEDs, organic diode lasers, and p-type semiconductors in OFETs [80,[234][235][236][237][238][239][240][241][242][243]. Noteworthy features are electroluminescence [237], and emission gain narrowing like spectrally narrowed emission (SNE) [244][245][246], and amplified spontaneous emission (ASE) caused by self-waveguide effects [247][248][249], and even mirrorless lasing [250,251].…”

Section: Discussionmentioning

confidence: 99%

“…Since para-phenylenes are twisted in the gas phase, the surface mobility of the vapour deposited molecules is high enough to migrate on the surface with long diffusion length, which results in promoted epitaxial growth. It has been demonstrated for different phenyl-thiophene co-oligomers with varying degrees of torque in the gas phase, vapour deposited onto KCl, that the rather coplanar molecules favour hit and stick growth, which results in inferior fiber growth [80]. However, the coplanar arrangement within the bulk structure is important for the nanofibers´optical properties because of a better conjugation of the π-electron systems.…”

Section: Fig 12mentioning

confidence: 99%

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Organic Molecular Nanotechnology

Schiek

Balzer

Al‐Shamery

et al. 2008

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Zur Homepage der Dissertation AbstractFormation of needle-like crystals from inorganic as well as from organic semiconductors such as para-phenylenes, α-thiophenes and phenyl-thiophene co-oligomers on dielectric surfaces has attracted increasing interest within the last years. The para-hexaphenylene has proven to be a versatile building block for generating long, parallely aligned organic nanofibers by a self-assembly process on a muscovite mica substrate via sublimation in high vacuum. These nanofibers possess outstanding optical properties like strong, polarised blue fluorescence in high quantum yields after unpolarised excitation with UV light, waveguiding and lasing features. Furthermore, they are chemically and thermically stable and can be easily detached from the growth substrate to serve as key elements in next generation optoelectronic and nanophotonic devices. Owing to their typical height and width on a nanometer scale and length up to one millimeter, the fibers bridge the gap between microscopic and macroscopic dimensions. The morphology of the nanofibers (length, height, width, aspect ratio, bending into rings) is susceptable to process parameters and pretreatment of the substrate. But chemically functionalisation of the molecular building block as key step of this thesis widens the scope of possibilities: Nanoaggregates with tailored morphology and optical properties are generated from designed functionalised molecular building blocks. Functional groups have been implemented at the 1,4´´´-para-positions of p-quaterphenylenes using a non-trivial Suzuki cross-coupling strategy. Symmetrically as well as non-symmetrically functionalised oligomers have been achieved in excellent yields and high purity. Additionally, the synthesis of phenyl-thiophene cooligomers and their acceptability for the nanofiber growth on muscovite mica via organic molecule deposition in high vacuum are presented. The fluorescence peak emission frequency of the nanostructures from the substituted p-quaterphenylenes shifts within the blue depending on the functionalisation. While dimensions are still influenced by the growth parameters, the overall shape (i.e. cross-section) of the aggregates alters significantly with the functional group. Even new properties like nonlinear optical activity are accessible. Due to intrinsic nonzero hyperpolarisability of push-pull functionalised oligomers, the respective nanofibers act as frequency doublers and emit strong second harmonic light after excitation with near infrared femtosecond laser pulses. Note that this design approach is possible while conserving the concept of highly crystalline nanofibers. Thus, a new route of bottom-up nanotechnology is presented starting from organic molecular synthesis towards generating of tailormade organic nanofibers opening new prospects for future nanotechnology. 3 ZusammenfassungDie Bildung von nadelförmigen Kristallen aus anorganischen und organischen Halbleitermolekülen wie zum Beispiel para-Phenylenen, α-Thiophenen und Phenylthiophen Co-oligomeren fa...

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Section: Ppttppsupporting

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Section: Fig 12mentioning

confidence: 99%

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Organic Molecular Nanotechnology

Schiek

Balzer

Al‐Shamery

et al. 2008

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“…We employed BP3T and P6T as the materials for the two additional donor layers, which provide light absorption but not charge separation. Thiophene/phenylene co-oligomers such as BP3T and P6T reportedly possess the good hole-transport characteristics necessary for the additional donor layers [21][22][23][24]. BP3T and P6T (Sumitomo Seika Industries), C 60 (Frontier Carbon), and BCP (TCI) were purified by temperature-gradient train sublimation with an Ar gas flow before use.…”

Section: Methodsmentioning

confidence: 99%

Cascade-type excitation energy relay in organic thin-film solar cells

Ichikawa¹,

Takekawa²,

Jeon³

et al. 2013

Organic Electronics

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We investigated small-molecule-based organic photovoltaic (PV) cells with three different electron-donating material layers, two thiophene/phenylene co-oligomers [-bis(biphenyl-4-yl)terthiophene (BP3T) and -diphenyl sexithiophene (P6T)] and copper phthalocyanine (CuPc), and one electron-accepting material layer (C 60 ). A cascade-type energy relay between the three donor layers occurred, and the incident photon-current conversion efficiency improved in the blue light region, where CuPc has very low optical absorption. An increase in P6T photoluminescence intensity in a 2 two-layer sample (BP3T/P6T) on quartz confirmed interlayer excitation transfer (ET) from BP3T and P6T. The bulk heterojunction architecture in our interlayer-ET-based organic PV cell was effective. Moreover, P6T appeared to have a relatively long exciton diffusion length of several tens of nanometers.

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“…As the additional p-type semiconducting material layers should possess a good hole-transporting ability ͑thiophene/phenylene͒, co-oligomers such as BP3T and P6T have already been studied and reported. [22][23][24][25] The following chemicals, BP3T and P6T ͑Sumitomo Seika Chemicals͒, and bathocuproine ͑BCP͒, Tokyo Chemical Industry ͑TCI͒ were purified by temperature gradient train sublimation with Ar gas flow before use. We used C 60 , purchased from Frontier carbon ͑nanom purple SUH grade͒, and CuPc ͑for the organic light-emitting device͒ donated by Nippon Steel Chemicals, without further purification.…”

Section: B Device Fabrication and Measurementsmentioning

confidence: 99%

Enhancing spectral contrast in organic red-light photodetectors based on a light-absorbing and exciton-blocking layered system

Higashi

Kim

Jeon

et al. 2010

Journal of Applied Physics

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We demonstrated a highly sensitive red-light photodetector based on a mixed copper phthalocyanine ͑CuPc͒ and fullerene C 60 photoactive layer, similar to a so-called bulk heterojunction structure usually used in the field of organic photovoltaics. We incorporated an additional set of organic layers that was composed of two organic p-type semiconductors to reduce the blue-light sensitivities of CuPc-and C 60 -based organic photodetectors. We used ␣ , -diphenyl sexi-thiophene ͑P6T͒ and ␣ , -bis͑biphenyl-4-yl͒ter-thiophene ͑BP3T͒, which are thiophene-based materials and usually have good hole-transporting properties. A thick ͑Ͼ100 nm͒ P6T layer absorbed blue light, preventing it from reaching the photoactive layer, and a thin ͑ϳ20 nm͒ BP3T layer whose band gap was larger than that of P6T blocked excitation energy transfer from P6T to CuPc. Thus, we successfully demonstrated a red-light photodetector with high peak sensitivity and whose current-voltage characteristics did not worsen. The optimal device showed a peak incident photon-current conversion efficiency of 51.7% at 620 nm and a specific detectivity of 4.0ϫ 10 11 cm Hz 1/2 / W.

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Comparative Carrier Transport Characteristics in Organic Field‐Effect Transistors with Vapor‐Deposited Thin Films and Epitaxially Grown Crystals of Biphenyl‐Capped Thiophene Oligomers

Cited by 77 publications

References 23 publications

Organic Molecular Nanotechnology

Organic Molecular Nanotechnology

Cascade-type excitation energy relay in organic thin-film solar cells

Enhancing spectral contrast in organic red-light photodetectors based on a light-absorbing and exciton-blocking layered system

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