The challenges involved in realizing
next-generation applications,
like robotics, artificial electronic skin, noninvasive healthcare
monitoring, motion detection, and so forth, enabled with wireless
human-machine interfaces, present a growing need for high-performance
flexible and wearable multifunctional electromechanical sensors. In
this regard, emerging classes of two-dimensional nanomaterials and
their hybrids show excellent promise as active sensing materials,
given their high flexibility and remarkable sensitivity to external
pressure and strain. This report is the first demonstration of SnS/Ti3C2T
x
nanohybrid-based
electromechanical sensors for use in applications like sign-to-text
translation and sitting posture analysis. The as-fabricated piezoresistive
sensor exhibits a high gauge factor and sensitivity value, that is,
7.41 and 7.49 kPa–1, respectively. Furthermore,
the nanohybrid-based sensor displayed a negligible change in performance
over ∼3500 and ∼2500 cycles for both pressure and strain
characterizations, indicating high robustness and exceptional stability.
The underlying intrinsic piezoresistive mechanism in layered nanomaterials
and the Ohmic contact formed at the SnS/Ti3C2T
x
heterojunction are explained in detail
with the help of energy band diagrams wherein the work function and
the E
homo values are extracted experimentally
by ultraviolet photoelectron spectroscopy for both SnS and Ti3C2T
x
. The successful
demonstration of sign-to-text translation and e-cushion applications
using SnS/Ti3C2T
x
nanohybrid-based piezoresistive sensors will further expand the
scope of flexible and wearable electronics research.
One-dimensional (1D) nanostructures
have received widespread attention
in optoelectronics due to their fascinating physical and chemical
properties that arise from quantum effects at the nanoscale. Furthermore,
there is scope to explore metal oxide-based 1D nanostructures and
their composites for developing high-performance optoelectronic devices.
This report is the first demonstration of a SnO2/MXene
1D nanofiber composite-based visible light photodetector on a rigid
p-type Si substrate. The SnO2 + MXene/Si(p) photodetector
was fabricated using a simple and economical electrospinning technique.
The responsivity (R) of the as-fabricated Si(p)/SnO2 + MXene photodetector displayed an enhanced value, i.e.,
∼64 AW–1, in comparison to that of the Si(p)/pristine
SnO2 photodetector (∼12 AW–1)
under a visible light illumination of 0.25 mW cm–2 and 554 nm wavelength, which suggests that MXene as a transport
layer vastly enhances the performance of the device. In addition,
the 1D nanofiber composite photodetector exhibited high-speed switching
characteristics with a response and recovery time of ∼123 and
∼60 ms, respectively. The excellent performance of the as-fabricated
photodetector can be attributed to three reasons mainly: (1) The MXene
acts as an electron acceptor, and charge transfer occurs across the
SnO2/MXene Schottky heterojunction, with photogenerated
electrons rapidly migrating to the MXene surface, where they get transported
and collected quickly (owing to the high mobility of charge carriers
in MXene) at the electrodes. (2) A high density of deep-level surface
states is present at the SnO2/MXene interface where minority
carriers (holes) get trapped and are unavailable for recombination,
thereby increasing the concentration of majority carriers (electrons).
(3) A built-in electric field at the main heterojunction between the
p-type Si and the 1D nanofiber composite assists the charge separation
of photogenerated carriers under an applied reverse bias. The successful
fabrication of such high-performance photodetectors is a significant
step in developing next-generation optoelectronic devices based on
novel composite nanomaterials with immense potential in diverse applications
across science and engineering domains.
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