3 research outputs found
Modulating Cationic Ratios for High-Performance Transparent Solution-Processed Electronics
Amorphous oxide semiconductors such
as indium zinc tin oxide (IZTO) are considered favorites to serve
as channel materials for thin film transistors (TFTs) because they
combine high charge carrier mobility with high optical transmittance,
allowing for the development of transparent electronics. Although
the influence of relative cationic concentrations in determining the
electronic properties have been studied in sputtered and PLD films,
the development of printed transparent electronics hinges on such
dependencies being explored for solution-processed systems. Here,
we study solution-processed indium zinc tin oxide thin film transistors
(TFTs) to investigate variation in their electrical properties with
change in cationic composition. Charge transport mobility ranging
from 0.3 to 20.3 cm<sup>2</sup>/(V s), subthreshold swing ranging
from 1.2 to 8.4 V/dec, threshold voltage ranging from â50 to
5 V, and drain current onâoff ratio ranging from 3 to 6 orders
of magnitude were obtained by examining different compositions of
the semiconductor films. Mobility was found to increase with the incorporation
of large cations such as In<sup>3+</sup> and Sn<sup>4+</sup> due to
the vast s-orbital overlap they can achieve when compared to the intercationic
distance. Subthreshold swing decreased with an increase in Zn<sup>2+</sup> concentration due to reduced interfacial state formation
between the semiconductor and dielectric. The optimized transistor
obtained at a compositional ratio of In/Zn/Sn = 1:1:1, exhibited a
high field-effect mobility of 8.62 cm<sup>2</sup>/(V s), subthreshold
swing of 1.75 V/dec, and current onâoff ratio of 10<sup>6</sup>. Such impressive performances reaffirm the promise of amorphous
metal oxide semiconductors for printed electronics
Transparent Flexible Multifunctional Nanostructured Architectures for Non-optical Readout, Proximity, and Pressure Sensing
Electronic skins need to be versatile
and able to detect multiple inputs beyond simple pressure and touch
while having attributes of transparency and facile manufacturability.
Herein, we demonstrate a versatile nanostructured transparent sensor
capable of detecting wide range of pressures and proximity as well
as novel nonoptical detection of printed patterns. The architecture
and fabrication processes are straightforward and show robustness
to repeated cycling and testing. The sensor displays good sensitivity
and stability from 30 Pa to 5 kPa without the use of microstructuration
and is conformal and sensitive to be utilized as a wrist-based heart-rate
monitor. Highly sensitive proximity detection is shown from a distance
of 9 cm. Finally, a unique nonoptical pattern recognition dependent
on the difference in the dielectric constant between ink and paper
is also demonstrated, indicating the multifunctionality of this simple
architecture
Strongly Confined CsPbBr<sub>3</sub> Quantum Dots as Quantum Emitters and Building Blocks for Rhombic Superlattices
The success of the colloidal semiconductor quantum dots
(QDs) field
is rooted in the precise synthetic control of QD size, shape, and
composition, enabling electronically well-defined functional nanomaterials
that foster fundamental science and motivate diverse fields of applications.
While the exploitation of the strong confinement regime has been driving
commercial and scientific interest in InP or CdSe QDs, such a regime
has still not been thoroughly explored and exploited for lead-halide
perovskite QDs, mainly due to a so far insufficient chemical stability
and size monodispersity of perovskite QDs smaller than about 7 nm.
Here, we demonstrate chemically stable strongly confined 5 nm CsPbBr3 colloidal QDs via a postsynthetic treatment employing didodecyldimethylammonium
bromide ligands. The achieved high size monodispersity (7.5% ±
2.0%) and shape-uniformity enables the self-assembly of QD superlattices
with exceptional long-range order, uniform thickness, an unusual rhombic
packing with an obtuse angle of 104°, and narrow-band cyan emission.
The enhanced chemical stability indicates the promise of strongly
confined perovskite QDs for solution-processed single-photon sources,
with single QDs showcasing a high single-photon purity of 73% and
minimal blinking (78% âonâ fraction), both at room temperature