Artificial
synapses/neurons based on electronic/ionic hybrid devices
have attracted wide attention for brain-inspired neuromorphic systems
since it is possible to overcome the von Neumann bottleneck of the
neuromorphic computing paradigm. Here, we report a novel photoneuromorphic
device based on printed photogating single-walled carbon nanotube
(SWCNT) thin film transistors (TFTs) using lightly n-doped Si as the
gate electrode. The drain currents of the printed SWCNT TFTs can gradually
increase to over 3000 times of their starting value after being pulsed
with light stimulation, and the electrical signals can maintain for
over 10 min. These characteristics are similar to the learning and
memory functions of brain-inspired neuromorphic systems. The working
mechanism of the light-stimulated neuromorphic devices is investigated
and described here in detail. Important synaptic characteristics,
such as low-pass filtering characteristics and nonvolatile memory
ability, are successfully emulated in the printed light-stimulated
artificial synapses. It demonstrates that the printed SWCNT TFT photoneuromorphic
devices can act as the nonvolatile memory units and perform photoneuromorphic
computing, which exhibits potential for future neuromorphic system
applications.
High quality p–n junctions based on 2D layered materials (2DLMs) are urgent to exploit, because of their unique properties such as flexibility, high absorption, and high tunability which may be utilized in next‐generation photovoltaic devices. Based on transfer technology, large amounts of vertical heterojunctions based on 2DLMs are investigated. However, the complicated fabrication process and the inevitable defects at the interfaces greatly limit their application prospects. Here, an in‐plane intramolecular WSe2 p–n junction is realized, in which the n‐type region and p‐type region are chemically doped by polyethyleneimine and electrically doped by the back‐gate, respectively. An ideal factor of 1.66 is achieved, proving the high quality of the p–n junction realized by this method. As a photovoltaic detector, the device possesses a responsivity of 80 mA W−1 (≈20% external quantum efficiency), a specific detectivity of over 1011 Jones and fast response features (200 µs rising time and 16 µs falling time) at zero bias, simultaneously. Moreover, a large open‐circuit voltage of 0.38 V and an external power conversion efficiency of ≈1.4% realized by the device also promises its potential in microcell applications.
Recently,
two-dimensional (2D) materials, especially transition-metal
dichalcogenides (TMDCs), have attracted extensive interest owing to
their potential applications in optoelectronics. Here, we demonstrate
a hybrid 2D–zero-dimensional (0D) photodetector, which consists
of a single-layer or few-layer molybdenum disulfide (MoS2) thin film and a thin layer of core/shell zinc cadmium selenide/zinc
sulfide (ZnCdSe/ZnS) colloidal quantum dots (QDs). It is worth mentioning
that the photoresponsivity of the hybrid 2D–0D photodetector
is 3 orders of magnitude larger than the TMDC photodetector (from
10 to 104 A W–1). The detectivity of
the hybrid structure detector is up to 1012 Jones, and
the gain is up to 105. Due to an effective energy transfer
from the photoexcited QD sensitizing layer to MoS2 films,
light absorption is enhanced and more excitons are generated. Thus,
this hybrid 2D–0D photodetector takes advantage of high charge
mobility in the MoS2 layer and efficient photon absorption/exciton
generation in the QDs, which suggests their promising applications
in the development of TMDC-based optoelectronic devices.
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