14 research outputs found
Biaxially Extended Conjugated Polymers with Thieno[3,2‑<i>b</i>]thiophene Building Block for High Performance Field-Effect Transistor Applications
Biaxially
thiophene side chain extended thienoÂ[3,2-<i>b</i>]Âthiophene
(TT2T)-based polymers, PTTT2T, P2TTT2T, PTTTT2T, and PTVTTT2T, were
synthesized by Stille coupling polymerization with different conjugated
moieties of thiophene (T), bithiophene (2T), thienoÂ[3,2-<i>b</i>]Âthiophene (TT), and thiophene–vinylene–thiophene (TVT),
respectively. The electronic properties of the prepared polymers could
be effectively tuned because the variant π-conjugated building
block affected the backbone conformation and the resulted morphology.
The morphology of the thin films characterized by atomic force microscopy
and grazing incidence X-ray diffraction showed that P2TTT2T and PTVTTT2T
thin films possessed a better molecular packing with a nanofiber structure
owing to their coplanar backbone. The average field-effect mobilities
of PTTT2T, P2TTT2T, PTTTT2T, and PTVTTT2T were 6.7 × 10<sup>–6</sup>, 0.36, 2.2 × 10<sup>–3</sup>, and 0.64 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> (maximum 0.71), respectively,
attributed to the coplanarity of polymer skeleton. In addition, the
fabricated FET devices showed a high on/off ratio over 10<sup>7</sup> under ambient for over 3 months, suggesting the excellent environmental
stability. The above results demonstrated that the biaxially extended
fused thiophene based conjugated polymers could serve as a potential
candidate for organic electronic device applications
Soft Poly(butyl acrylate) Side Chains toward Intrinsically Stretchable Polymeric Semiconductors for Field-Effect Transistor Applications
PolyÂ(butyl acrylate)
(PBA) side chain equipped isoindigo-bithiophene
(II2T) conjugated polymers have been designed and synthesized for
stretchable electronic applications. The PBA segment possesses low
glass transition temperature and high softness, offering a great opportunity
to improve the mechanical property of semiconducting polymer thin
films that typically contain lots of rigid conjugated rings. Polymers
with 0, 5, 10, 20 and 100% of PBA side chains, named <b>PII2T</b>, <b>PII2T-PBA5</b>, <b>PII2T-PBA10</b>, <b>PII2T-PBA20</b>, and <b>PII2T-PBA100</b>, were explored, and their polymer
properties, surface morphology, electrical characteristics, and strain-dependent
performance were investigated systematically. The series polymers
showed a charge carrier mobility of 0.06–0.8 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> with an on/off current
ratio over 10<sup>5</sup> dependent on different amounts of PBA chains
as probed using a top-contact transistor device. Moreover, we can
still achieve a mobility higher than 0.2 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> even if 10% of PBA side chains were added
(i.e., <b>PII2T-PBA10</b>). Such <b>PII2T-PBA</b> polymers,
more attractive, exhibited superior thin film ductility with a low
tensile modulus down to 0.12 GPa (<b>PII2T-PBA20</b>) due to
the soft PBA side chain. The more PBA segment was incroporated, the
lower modulus was reached. The mobility performance, at the same time,
remained approximately 0.08 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> based on <b>PII2T-PBA10</b> films even under
a 60% strain and could be simultaneously operated over 400 stretching/releasing
cycles without significant electrical degradations. The above results
suggest that the rational design of soft PBA side chains provides
a great potential for next-generation soft and wearable electronic
applications
Isoindigo-Based Semiconducting Polymers Using Carbosilane Side Chains for High Performance Stretchable Field-Effect Transistors
Isoindigo-based conjugated polymers,
PII2T-C6 and PII2T-C8, with carbosilane side chains have been designed
and synthesized for stretchable electronic applications. The carbosilane
side chains offerred a simple synthetic pathway to evaluate long and
branched side chains in high yields and were prepared with a six or
eight linear spacer plus two hexyl or octyl chains after branching.
The studied polymers showed a high charge carrier mobility of 8.06
cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> with an
on/off current ratio of 10<sup>6</sup> as probed using a top-contact
transistor device with organized solid state molecular packing structures,
as investigated through grazing-incidance X-ray diffreaction (GIXD)
and atomic force microscopy (AFM) technique systematically. The studied
polymers, more attractive, exhibited superior thin film ductility
with a low tensile modulus in a range of 0.27–0.43 GPa owing
to the branched carbosilane side chain, and their mobility was remained
higher than 1 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> even under a 60% strain along parallel or perpendicular direction
to the tensile strain. Such polymer films, in addition, can be simultaneously
operated over 400 stretching/releasing cycles and maintained stable
electrical properties, suggesting the newly designed materials possessed
great potential for next-generation skin-inspired wearable electronic
application with high charge carrier mobility, low tensile modulus,
and stable device characteristics during stretching
Stretchable Conjugated Rod–Coil Poly(3-hexylthiophene)-<i>block</i>-poly(butyl acrylate) Thin Films for Field Effect Transistor Applications
We
report the synthesis, morphology, and properties of polyÂ(3-hexylthiophene)-<i>block</i>-polyÂ(butyl acrylate) (P3HT-<i>b</i>-PBA)
for stretchable electronics applications, which are consisted of semiconducting
P3HT and low glass transistion temperature (<i>T</i><sub>g</sub>) PBA blocks. The P3HT-<i>b</i>-PBA thin films self-assembled
into fibrillar-like nanostructures and maintained the edge-on oreientation
even at a low P3HT composition, based on the results from atomic force
microscopy (AFM) and grazing incidence X-ray diffraction (GIXD). By
varying the P3HT/PBA ratio, the tensile modulus decreased as the block
length of PBA increased, from 0.93 GPa for P3HT to 0.19 GPa for P3HT-<i>b</i>-PBA<sub>12k</sub>. The field effect transistor (FET) using
P3HT-<i>b</i>-PBA as the active layer exhibited a high p-type
mobility over 10<sup>–2</sup> cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>, indicating its good charge transporting ability.
Furthermore, the P3HT-<i>b</i>-PBA<sub>6k</sub> based FET
under 100% strain had a high mobility of 2.5 × 10<sup>–2</sup> cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> with
an on/off ratio of 7.2 × 10<sup>6</sup>, and it maintained over
10<sup>–2</sup> cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> for 1000 cycles, suggesting the promising stability
and reproducbility. The result demonstrated that the newly designed
conjugated rod–coil block copolymers could have potential applications
in stretchable electronic devices
A Rapid and Facile Soft Contact Lamination Method: Evaluation of Polymer Semiconductors for Stretchable Transistors
Organic stretchable electronics have
attracted extensive scientific
and industrial interest because they can be stretched, twisted, or
compressed, enabling the next-generation of organic electronics for
human/machine interfaces. These electronic devices have already been
described for applications such as field-effect transistors, photovoltaics,
light-emitting diodes, and sensors. High-performance stretchable electronics,
however, currently still involve complicated processing steps to integrate
the substrates, semiconductors, and electrodes for effective performance.
Herein, we describe a facile method to efficiently identify suitable
semiconducting polymers for organic stretchable transistors using
soft contact lamination. In our method, the various polymers investigated
are first transferred on an elastomeric polyÂ(dimethylsiloxane) (PDMS)
slab and subsequently stretched (up to 100%) along with the PDMS.
The polymer/PDMS matrix is then laminated on source/drain electrode-deposited
Si substrates equipped with a PDMS dielectric layer. Using this device
configuration, the polymer semiconductors can be repeatedly interrogated
with laminate/delaminate cycles under different amounts of tensile
strain. From our obtained electrical characteristics, e.g., mobility,
drain current, and on/off ratio, the strain limitation of semiconductors
can be derived. With a facile soft contact lamination testing approach,
we can thus rapidly identify potential candidates of semiconducting
polymers for stretchable electronics
Nonhalogenated Solvent Processable and Printable High-Performance Polymer Semiconductor Enabled by Isomeric Nonconjugated Flexible Linkers
One
major advantage of organic electronics is their superior processability
relative to traditional silicon-based materials. However, most high-performing
polymer semiconductors exhibit poor solubility and require toxic chlorinated
solvents coupled with inefficient coating methods such as spin-coating
for device fabrication. Therefore, developing polymer semiconductors
that are processable in environmentally benign solvents and compatible
with effective printing techniques while maintaining good charge transport
properties is crucial for the industrialization of low-cost and lightweight
plastic electronics. In this study, alkyl flexible linkers with branched
tertiary carbon atoms are inserted to a high-mobility diketopyrrolopyrrole-based
polymer backbone to suppress polymer aggregation in solution, decrease
crystallinity, and increase free volume. The polymer readily dissolves
in industrial solvents and shows a 70-fold increase in solubility
compared to its fully conjugated counterpart. Furthermore, due to
its high solubility, the polymer can be inkjet-printed and solution-sheared
at high concentrations using eco-friendly solvents such as <i>p</i>-xylene and 2-methyltetraÂhydrofuran with a maximum
hole mobility of 2.76 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> and on–off ratio above 10<sup>5</sup> in organic field-effect
transistors
Quadruple H‑Bonding Cross-Linked Supramolecular Polymeric Materials as Substrates for Stretchable, Antitearing, and Self-Healable Thin Film Electrodes
Herein,
we report a de novo chemical design of supramolecular polymer materials
(SPMs-<b>1</b>–<b>3</b>) by condensation polymerization,
consisting of (i) soft polymeric chains (polytetramethylene glycol
and tetraethylene glycol) and (ii) strong and reversible quadruple
H-bonding cross-linkers (from 0 to 30 mol %). The former contributes
to the formation of the soft domain of the SPMs, and the latter furnishes
the SPMs with desirable mechanical properties, thereby producing soft,
stretchable, yet tough elastomers. The resulting SPM-<b>2</b> was observed to be highly stretchable (up to 17 000% strain),
tough (fracture energy ∼30 000 J/m<sup>2</sup>), and
self-healing, which are highly desirable properties and are superior
to previously reported elastomers and tough hydrogels. Furthermore,
a gold, thin film electrode deposited on this SPM substrate retains
its conductivity and combines high stretchability (∼400%),
fracture/notch insensitivity, self-healing, and good interfacial adhesion
with the gold film. Again, these properties are all highly complementary
to commonly used polydimethylsiloxane-based thin film metal electrodes.
Last, we proceed to demonstrate the practical utility of our fabricated
electrode via both in vivo and in vitro measurements of electromyography
signals. This fundamental understanding obtained from the investigation
of these SPMs will facilitate the progress of intelligent soft materials
and flexible electronics
Quadruple H‑Bonding Cross-Linked Supramolecular Polymeric Materials as Substrates for Stretchable, Antitearing, and Self-Healable Thin Film Electrodes
Herein,
we report a de novo chemical design of supramolecular polymer materials
(SPMs-<b>1</b>–<b>3</b>) by condensation polymerization,
consisting of (i) soft polymeric chains (polytetramethylene glycol
and tetraethylene glycol) and (ii) strong and reversible quadruple
H-bonding cross-linkers (from 0 to 30 mol %). The former contributes
to the formation of the soft domain of the SPMs, and the latter furnishes
the SPMs with desirable mechanical properties, thereby producing soft,
stretchable, yet tough elastomers. The resulting SPM-<b>2</b> was observed to be highly stretchable (up to 17 000% strain),
tough (fracture energy ∼30 000 J/m<sup>2</sup>), and
self-healing, which are highly desirable properties and are superior
to previously reported elastomers and tough hydrogels. Furthermore,
a gold, thin film electrode deposited on this SPM substrate retains
its conductivity and combines high stretchability (∼400%),
fracture/notch insensitivity, self-healing, and good interfacial adhesion
with the gold film. Again, these properties are all highly complementary
to commonly used polydimethylsiloxane-based thin film metal electrodes.
Last, we proceed to demonstrate the practical utility of our fabricated
electrode via both in vivo and in vitro measurements of electromyography
signals. This fundamental understanding obtained from the investigation
of these SPMs will facilitate the progress of intelligent soft materials
and flexible electronics
Quadruple H‑Bonding Cross-Linked Supramolecular Polymeric Materials as Substrates for Stretchable, Antitearing, and Self-Healable Thin Film Electrodes
Herein,
we report a de novo chemical design of supramolecular polymer materials
(SPMs-<b>1</b>–<b>3</b>) by condensation polymerization,
consisting of (i) soft polymeric chains (polytetramethylene glycol
and tetraethylene glycol) and (ii) strong and reversible quadruple
H-bonding cross-linkers (from 0 to 30 mol %). The former contributes
to the formation of the soft domain of the SPMs, and the latter furnishes
the SPMs with desirable mechanical properties, thereby producing soft,
stretchable, yet tough elastomers. The resulting SPM-<b>2</b> was observed to be highly stretchable (up to 17 000% strain),
tough (fracture energy ∼30 000 J/m<sup>2</sup>), and
self-healing, which are highly desirable properties and are superior
to previously reported elastomers and tough hydrogels. Furthermore,
a gold, thin film electrode deposited on this SPM substrate retains
its conductivity and combines high stretchability (∼400%),
fracture/notch insensitivity, self-healing, and good interfacial adhesion
with the gold film. Again, these properties are all highly complementary
to commonly used polydimethylsiloxane-based thin film metal electrodes.
Last, we proceed to demonstrate the practical utility of our fabricated
electrode via both in vivo and in vitro measurements of electromyography
signals. This fundamental understanding obtained from the investigation
of these SPMs will facilitate the progress of intelligent soft materials
and flexible electronics
Quadruple H‑Bonding Cross-Linked Supramolecular Polymeric Materials as Substrates for Stretchable, Antitearing, and Self-Healable Thin Film Electrodes
Herein,
we report a de novo chemical design of supramolecular polymer materials
(SPMs-<b>1</b>–<b>3</b>) by condensation polymerization,
consisting of (i) soft polymeric chains (polytetramethylene glycol
and tetraethylene glycol) and (ii) strong and reversible quadruple
H-bonding cross-linkers (from 0 to 30 mol %). The former contributes
to the formation of the soft domain of the SPMs, and the latter furnishes
the SPMs with desirable mechanical properties, thereby producing soft,
stretchable, yet tough elastomers. The resulting SPM-<b>2</b> was observed to be highly stretchable (up to 17 000% strain),
tough (fracture energy ∼30 000 J/m<sup>2</sup>), and
self-healing, which are highly desirable properties and are superior
to previously reported elastomers and tough hydrogels. Furthermore,
a gold, thin film electrode deposited on this SPM substrate retains
its conductivity and combines high stretchability (∼400%),
fracture/notch insensitivity, self-healing, and good interfacial adhesion
with the gold film. Again, these properties are all highly complementary
to commonly used polydimethylsiloxane-based thin film metal electrodes.
Last, we proceed to demonstrate the practical utility of our fabricated
electrode via both in vivo and in vitro measurements of electromyography
signals. This fundamental understanding obtained from the investigation
of these SPMs will facilitate the progress of intelligent soft materials
and flexible electronics