مجال
التميز
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تميز دراسي وبحثي
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البحوث المنشورة
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البحث (1):
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عنوان البحث:
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An ionic liquid-gated polymer thin film
transistor with exceptionally low “on” resistance
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رابط إلى البحث:
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Click
here
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تاريخ النشر:
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05/05/2014
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موجز عن البحث:
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We report the ionic liquid (IL) gating
of a solution processed semiconducting polymer,
poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT).
IL gating relies on the poor solubility of PBTTT, which requires hot
chlorinated benzenes for solution processing. PBTTT, thus, resists
dissolution even in IL, which otherwise rapidly dissolves semiconducting
polymers. The resulting organic thin film transistors (OTFTs) display low
threshold, very high carrier mobility (>3 cm2/Vs), and deliver high currents
(in the order of 1 mA) at low operational voltages. Such OTFTs are
interesting both practically, for the addressing of current-driven devices
(e.g., organic LEDs), and for the study of charge transport in semiconducting
polymers at very high carrier density.
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البحث ( 2 ):
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عنوان البحث:
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Precursor-route
ZnO films from a mixed casting solvent for high performance aqueous
electrolyte-gated transistors
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تاريخ النشر:
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26/10/2015
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We
significantly improved the performance of precursor-route semiconducting zinc
oxide (ZnO) films in electrolyte-gated thin film transistors (TFTs). We find
that the organic precursor to ZnO, zinc acetate (ZnAc), dissolves more
readily in a 1
:
1 mixture of ethanol (EtOH) and acetone
than in pure EtOH, pure acetone, or pure isopropanol. XPS and SEM
characterisation show improved morphology of ZnO films converted from a mixed
solvent cast ZnAc precursor compared to the EtOH cast precursor. When gated
with a biocompatible electrolyte, phosphate buffered saline (PBS), ZnO thin
film transistors (TFTs) derived from mixed solvent cast ZnAc give 4 times
larger field effect current than similar films derived from ZnAc cast from pure
EtOH. The sheet resistance at VG = VD = 1 V is 30 kΩ □−1,
lower than for any organic TFT, and lower than for any electrolyte-gated ZnO
TFT reported to date.
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البحث (3):
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عنوان البحث:
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Integration
of additive manufacturing and inkjet printed electronics: a potential route
to parts with embedded multifunctionality
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here
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تاريخ النشر:
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11/04/2016
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Additive manufacturing, an umbrella term for
a number of different manufacturing techniques, has attracted increasing
interest recently for a number of reasons, such as the facile customisation
of parts, reduced time to manufacture from initial design, and possibilities
in distributed manufacturing and structural electronics. Inkjet printing is
an additive manufacturing technique that is readily integrated with other
manufacturing processes, eminently scalable and used extensively in printed
electronics. It therefore presents itself as a good candidate for integration
with other additive manufacturing techniques to enable the creation of parts
with embedded electronics in a timely and cost effective manner. This review
introduces some of the fundamental principles of inkjet printing; such as
droplet generation, deposition, phase change and post-deposition processing.
Particular focus is given to materials most relevant to incorporating
structural electronics and how post-processing of these materials has been
able to maintain compatibility with temperature sensitive substrates.
Specific obstacles likely to be encountered in such an integration and
potential strategies to address them will also be discussed.
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البحث (4):
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عنوان البحث:
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A
water-gated organic thin film transistor as a sensor for water-borne amines
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here
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تاريخ النشر:
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01/06/2016
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موجز عن البحث:
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The
p-type semiconducting
polymer Poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT)
displays innate sensitivity to water-borne amines. We demonstrate this with
the help of water-gated PBTTT thin film transistors (TFTs). When octylamine
is added to the gating water, TFTs respond with a significantly reduced
saturated drain current. Underlying TFT drift is minimised by initial
conditioning, and remaining drift can be accounted for by normalising current
response to the current level under purge immediately before exposure.
Normalised current response vs. amine concentration is reproducible
between different transistors, and can be modelled by a Langmuir surface
adsorption isotherm, which suggests physisorption of analyte at the PBTTT
surface, rather than bulk penetration. Same PBTTT transistors do not respond
to 1- octanol, confirming the specific affinity between amines and thiophene-
based organic semiconductors.
Graphical
abstract
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البحث (5):
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عنوان البحث:
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A
membrane-free cation selective water-gated transistor
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رابط إلى البحث:
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here
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تاريخ النشر:
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19/07/2016
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موجز عن البحث:
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Sensors
for the detection of waterborne cations are of great practical interest, and
chemistry has synthesised a formidable catalogue of cation selective
complexation agents (‘ionophores’) as selective sensitisers. Current
ionophore-based sensors separate the complexation of the cation by the
ionophore, and the transduction of complexation into an electrical signal,
into separate components. We here unite both functions into a single,
sensitised semiconducting layer of a water-gated organic thin film transistor
(OTFT). The resulting OTFT transduces waterborne cations into an electrical
signal with same selectivity, sensitivity, and limit of detection as
established sensors at much simplified preparation and operation. This opens
a new route to apply the ‘ionophore’ family of functional organic materials
in practical cation sensors.
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البحث (6):
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عنوان البحث:
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A New
Precursor Route to Semiconducting Zinc Oxide
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تاريخ النشر:
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26/08/2016
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موجز عن البحث:
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We demonstrate a new precursor route toward
solution-processed films of the II-VI semiconductor zinc oxide (ZnO). Spray pyrolysis
of aqueous solutions of the zinc salt zinc chloride (ZnCl2) onto a substrate
heated to at least 250 °C gives films that are insoluble in water, display an
absorption edge at 365 nm, and when electrically gated display thin film
transistor characteristics similar to ZnO films derived via the established
zinc acetate (ZnAc) precursor route; we, therefore, identify it as ZnO.
Control experiments attempting spray pyrolysis of aqueous zinc sulfate
solutions, and delayed pyrolysis of cold-sprayed and dried ZnCl2 films, do
not lead to semiconducting films. Formation of ZnO from an aqueous Zinc salt
requires the simultaneous presence of zinc ions, chloride ions, and water, at
the time of pyrolysis. We, therefore, suggest that the actual ZnO precursor
is the ZnClxH2O(4-x) species that forms when ZnCl2 dissolves in water [The
Journal of Chemical Physics 39, 3436 (1963)]. The reported process is easy to
upscale for large area ZnO coatings, e.g., on window panes for therm
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البحث (7):
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عنوان البحث:
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Innate cation
sensitivity in a semiconducting polymer
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here
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تاريخ النشر:
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01/09/2016
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موجز عن البحث:
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Water-gated
organic thin film transistors (OTFTs) using the hole transporting
semiconducting polymer,
poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT), show
an innate response of their threshold voltage to the addition of divalent metal
cations to the gating water, without deliberately introducing an
ion-sensitive component. A similar threshold response is shown for several
divalent cations, but is absent for monovalent cations. Response is absent
for transistors using the inorganic semiconductor ZnO, or the similar organic
semiconductor poly(3-hexylthiophene) (rrP3HT), instead of PBTTT. We assign
innate cation sensitivity to residues of the organometallic Pd(0) complex
used as catalyst in PBTTT synthesis which bears strong resemblance to typical
metal chelating agents. Organometallic Pd(0) residues are absent from ZnO,
and also from rrP3HT which is polymerised with a different type of catalyst.
However, when Pd(0) complex is deliberately added to rrP3HT casting
solutions, resulting OTFTs also display threshold response to a divalent
cation.
Graphical
abstract
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المؤتمرات العلمية:
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المؤتمر (1):
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عنوان المؤتمر:
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UK
Semiconductors 2014 Conference
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تاريخ الإنعقاد:
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09/07/2014
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مكان
الإنعقاد:
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Sheffield,
UK
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طبيعة المشاركة:
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Poster
presentation
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عنوان المشاركة:
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An ionic
liquid- gated polymer thin film transistor with exceptionally low ‘on’
resistance
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ملخص المشاركة:
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We
present the first ionic liquid (IL) gating of a high mobility solution
processed semiconducting polymer, poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-
b]thiophene) (PBTTT). IL gating relies on the poor solubility of PBTTT, which
resists dissolution even in IL. Resulting organic thin film transistors
(OTFTs) display low threshold, very high carrier mobility (>3cm2/Vs), and
deliver high currents (in the order of 1mA) at low voltages.
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