7 research outputs found
Noninvasive and Direct Patterning of High-Resolution Full-Color Quantum Dot Arrays by Programmed Microwetting
Although the commercialization of electroluminescent
quantum-dot
(QD) displays essentially demands multicolor patterning of QDs with
sufficient scalability and uniformity, the implementation of QD patterning
in a light-emitting diode device is highly challenging, mainly due
to the innate vulnerability of QDs and charge-transport layers. Here,
we introduce a noninvasive surface-wetting approach for patterning
full-color QD arrays on a photoprogrammed hole-transport layer (HTL).
To achieve noninvasiveness of QD patterning, surface-specific modification
of HTLs was performed without degrading their performance. Moreover,
engineering the solvent evaporation kinetics allows area-selective
wetting of QD patterns with a uniform thickness profile. Finally,
multicolor QD patterning was enabled by preventing cross-contamination
between different QD colloids via partial fluoro-encapsulation of
earlier-patterned QDs. Throughout the overall QD patterning process,
the optoelectronic properties of QDs and hole-transport layers are
well preserved, and prototype electroluminescent quantum dot light-emitting
diode arrays with high current efficiency and brightness were realized
Multimodal Characterization of Cardiac Organoids Using Integrations of Pressure-Sensitive Transistor Arrays with Three-Dimensional Liquid Metal Electrodes
Herein, we present an unconventional method for multimodal
characterization
of three-dimensional cardiac organoids. This method can monitor and
control the mechanophysiological parameters of organoids within a
single device. In this method, local pressure distributions of human-induced
pluripotent stem-cell-derived cardiac organoids are visualized spatiotemporally
by an active-matrix array of pressure-sensitive transistors. This
array is integrated with three-dimensional electrodes formed by the
high-resolution printing of liquid metal. These liquid-metal electrodes
are inserted inside an organoid to form the intraorganoid interface
for simultaneous electrophysiological recording and stimulation. The
low mechanical modulus and low impedance of the liquid-metal electrodes
are compatible with organoids’ soft biological tissue, which
enables stable electric pacing at low thresholds. In contrast to conventional
electrophysiological methods, this measurement of a cardiac organoid’s
beating pressures enabled simultaneous treatment of electrical therapeutics
using a single device without any interference between the pressure
signals and electrical pulses from pacing electrodes, even in wet
organoid conditions
Multimodal Characterization of Cardiac Organoids Using Integrations of Pressure-Sensitive Transistor Arrays with Three-Dimensional Liquid Metal Electrodes
Herein, we present an unconventional method for multimodal
characterization
of three-dimensional cardiac organoids. This method can monitor and
control the mechanophysiological parameters of organoids within a
single device. In this method, local pressure distributions of human-induced
pluripotent stem-cell-derived cardiac organoids are visualized spatiotemporally
by an active-matrix array of pressure-sensitive transistors. This
array is integrated with three-dimensional electrodes formed by the
high-resolution printing of liquid metal. These liquid-metal electrodes
are inserted inside an organoid to form the intraorganoid interface
for simultaneous electrophysiological recording and stimulation. The
low mechanical modulus and low impedance of the liquid-metal electrodes
are compatible with organoids’ soft biological tissue, which
enables stable electric pacing at low thresholds. In contrast to conventional
electrophysiological methods, this measurement of a cardiac organoid’s
beating pressures enabled simultaneous treatment of electrical therapeutics
using a single device without any interference between the pressure
signals and electrical pulses from pacing electrodes, even in wet
organoid conditions
Multimodal Characterization of Cardiac Organoids Using Integrations of Pressure-Sensitive Transistor Arrays with Three-Dimensional Liquid Metal Electrodes
Herein, we present an unconventional method for multimodal
characterization
of three-dimensional cardiac organoids. This method can monitor and
control the mechanophysiological parameters of organoids within a
single device. In this method, local pressure distributions of human-induced
pluripotent stem-cell-derived cardiac organoids are visualized spatiotemporally
by an active-matrix array of pressure-sensitive transistors. This
array is integrated with three-dimensional electrodes formed by the
high-resolution printing of liquid metal. These liquid-metal electrodes
are inserted inside an organoid to form the intraorganoid interface
for simultaneous electrophysiological recording and stimulation. The
low mechanical modulus and low impedance of the liquid-metal electrodes
are compatible with organoids’ soft biological tissue, which
enables stable electric pacing at low thresholds. In contrast to conventional
electrophysiological methods, this measurement of a cardiac organoid’s
beating pressures enabled simultaneous treatment of electrical therapeutics
using a single device without any interference between the pressure
signals and electrical pulses from pacing electrodes, even in wet
organoid conditions
Multimodal Characterization of Cardiac Organoids Using Integrations of Pressure-Sensitive Transistor Arrays with Three-Dimensional Liquid Metal Electrodes
Herein, we present an unconventional method for multimodal
characterization
of three-dimensional cardiac organoids. This method can monitor and
control the mechanophysiological parameters of organoids within a
single device. In this method, local pressure distributions of human-induced
pluripotent stem-cell-derived cardiac organoids are visualized spatiotemporally
by an active-matrix array of pressure-sensitive transistors. This
array is integrated with three-dimensional electrodes formed by the
high-resolution printing of liquid metal. These liquid-metal electrodes
are inserted inside an organoid to form the intraorganoid interface
for simultaneous electrophysiological recording and stimulation. The
low mechanical modulus and low impedance of the liquid-metal electrodes
are compatible with organoids’ soft biological tissue, which
enables stable electric pacing at low thresholds. In contrast to conventional
electrophysiological methods, this measurement of a cardiac organoid’s
beating pressures enabled simultaneous treatment of electrical therapeutics
using a single device without any interference between the pressure
signals and electrical pulses from pacing electrodes, even in wet
organoid conditions
In Situ Doping System To Improve the Electric-Field-Induced Fluorescence Properties of CdZnS/ZnS Quantum Rods for Light-Emitting Devices
One-dimensional quantum
rods (QRs) have the properties of the electron
and hole are separated under the electric field, the overlap of the
wave function decreases, and photoluminescence quenching occurs. Because
of these properties, QRs can be used in optical switching and future
display applications. The CdZnS/ZnS QR is a material capable of emitting
blue light. CdZnS/ZnS can easily separate carriers because the difference
between the valence band of the core and the shell is small. However,
CdS and ZnS have very low hole conductivity and cannot easily be separated.
To solve this problem, we developed an in situ doping system and demonstrated
nitrogen doping. The in situ doping system not only coats ZnS onto
CdZnS QRÂ but also proceeds with nitrogen doping. Previously studied
doping methods additionally doped the synthesized nanomaterials and
had no effect of doping because the dopant was not dispersed without
subsequent heat treatment. However, the in situ doping system grows
the ZnS shell and uniformly dopes the nitrogen. This means that no
additional heat treatment is required. The effect of doping gradually
increases in proportion to the amount of dopant and the PL quenching
increases, even though the aspect ratio is decreased
Conductivity Enhancement of Nickel Oxide by Copper Cation Codoping for Hybrid Organic-Inorganic Light-Emitting Diodes
We
demonstrate a CuÂ(I) and CuÂ(II) codoped nickelÂ(II) oxide (NiO<sub><i>x</i></sub>) hole injection layer (HIL) for solution-processed
hybrid organic-inorganic light-emitting diodes (HyLEDs). Codoped NiO<sub><i>x</i></sub> films show no degradation on optical properties
in the visible range (400–700 nm) but have enhanced electrical
properties compared to those of conventional CuÂ(II)-only doped NiO<sub><i>x</i></sub> film. Codoped NiO<sub><i>x</i></sub> film shows an over four times increased vertical current in
comparison with that of NiO<sub><i>x</i></sub> in conductive
atomic force microscopy (c-AFM) configuration. Moreover, the hole
injection ability of codoped NiO<sub><i>x</i></sub> is also
improved, which has ionization energy of 5.45 eV, 0.14 eV higher than
the value of NiO<sub><i>x</i></sub> film. These improvements
are a consequence of surface chemical composition change in NiO<sub><i>x</i></sub> due to Cu cation codoping. More off-stoichiometric
NiO<sub><i>x</i></sub> formed by codoping includes a large
amount of Ni vacancies, which lead to better electrical properties.
Density functional theory calculations also show that Cu doped NiO
model structure with Ni vacancy contains diverse oxidation states
of Ni based on both density of states and partial atomic charge analysis.
Finally, HyLEDs of Cu codoped NiO<sub><i>x</i></sub> HIL
have higher performance comparing with those of pristine NiO<sub><i>x</i></sub>. The current efficiency of devices with NiO<sub><i>x</i></sub> and codoped NiO<sub><i>x</i></sub> HIL are 11.2 and 15.4 cd/A, respectively. Therefore, codoped NiO<sub><i>x</i></sub> is applicable to various optoelectronic
devices due to simple sol–gel process and enhanced doping efficiency