MoS2 quantum dots (QDs)‐based white‐light‐emitting diodes (QD‐WLEDs) are designed, fabricated, and demonstrated. The highly luminescent, histidine‐doped MoS2 QDs synthesized by microwave induced ...fragmentation of 2D MoS2 nanoflakes possess a wide distribution of available electronic states as inferred from the pronounced excitation‐wavelength‐dependent emission properties. Notably, the histidine‐doped MoS2 QDs show a very strong emission intensity, which exceeds seven times of magnitude larger than that of pristine MoS2 QDs. The strongly enhanced emission is mainly attributed to nitrogen acceptor bound excitons and passivation of defects by histidine‐doping, which can enhance the radiative recombination drastically. The enabled electroluminescence (EL) spectra of the QD‐WLEDs with the main peak around 500 nm are found to be consistent with the photoluminescence spectra of the histidine‐doped MoS2 QDs. The enhanced intensity of EL spectra with the current increase shows the stability of histidine‐doped MoS2 based QD‐WLEDs. The typical EL spectrum of the novel QD‐WLEDs has a Commission Internationale de l'Eclairage chromaticity coordinate of (0.30, 0.36) exhibiting an intrinsic broadband white‐light emission. The unprecedented and low‐toxicity QD‐WLEDs based on a single light‐emitting material can serve as an excellent alternative for using transition metal dichalcogenides QDs as next generation optoelectronic devices.
A “single light‐emitting material,” “low‐toxicity,” and “economical fabrication process” white‐light‐emitting diode based on histidine‐doped MoS2 quantum dots is successfully designed, fabricated, and demonstrated. This work overcomes the low‐luminescence problem for traditional 2D transition metal dichalcogenides and achieves high performance white‐light‐emitting diodes with an intrinsic broadband white‐light electroluminescence and a Commission Internationale de l'Eclairage chromaticity coordinate of (0.30, 0.36).
Nonvolatile memory is an indispensable component of electronic devices. However, the current technology makes it difficult to satisfy the emerging big data demand. To circumvent the existing ...problems, herein, a first attempt is made to achieve multifunctional nonvolatile memory based on all 2D heterostructures, consisting of histidine‐doped molybdenum disulfide quantum disks mixed with graphene oxide and a graphene macroscopic heterojunction. The designed device possesses intriguing hybrid electrically and optically controllable nonvolatile memory functionalities. By harnessing the unique properties of these materials, memory devices demonstrate long‐term stability and nonvolatile characteristics under both optical and electrical control signals. These devices possess outstanding features, such as multiple read‐write cycles, multi levels, and fast switching speeds, overcoming the limitations of traditional components. To explore the underlying physical mechanism, the Fermi level of graphene is measured and it is confirmed that the charge transfer and trapping across the heterojunctions are the major factors responsible for the observed behavior. This study demonstrates that 2D heterostructures for hybrid optically and electrically controllable nonvolatile memory pave an alternative route for the next‐generation information technology.
2D heterostructures for hybrid optically and electrically controllable nonvolatile memory are demonstrated that have excellent capability for applications in the next‐generation information technology.
The development of two‐dimensional (2D) materials has brought the breakthrough for scientific discoveries and widespread applications in many emerging devices. However, the related study on lasers is ...rather limited. In this study, a stretchable and broadband cavity‐free laser device based on all 2D metamaterials consisting of molybdenum disulfide (MoS2)/graphene nanocomposites is designed and demonstrated. When the pumping power density of the device is more than 200 W cm−2, multiple pronounced narrow peaks with linewidth <0.5 nm superimpose on the spectra, providing the signature for laser actions. The optical properties of MoS2/graphene meta‐nanocomposites for MoS2 quantum dots (QDs) with different concentration of l‐histidine doping are also examined. It is emphasized that under optimized doping concentration of MoS2 QDs, the laser action of the device can be effectively enhanced. Furthermore, it is shown that the laser action of the devices is controllable by applying an external strain. It is demonstrated that after stretching for more than 200 times, the performance still remains the same with negligible change, indicating the robustness of the device. The presented stretchable laser devices based on all 2D meta‐nanocomposites therefore can open new possibilities for future developments of not‐yet realized optoelectronic devices.
This is the first attempt to demonstrate a stretchable and broadband cavity‐free laser device based on all 2D metamaterials consisting of MoS2/graphene nanocomposites. Under the optimized doping concentration of MoS2 quantum dots, laser actions of the device can be effectively enhanced. Furthermore, it is shown that laser actions of the device are controllable by applying an external strain.
Random lasers exhibit many exotic properties, including chaotic behavior, light localization, broad angular emission, and cost-effective fabrication, which enable them to attract both scientific and ...industrial interests. However, before the realization of their potential applications, several challenges still remain including the underlying mechanism and controllability due to their inherent multidirectional and chaotic fluctuations. Through more than two decades of collaborative efforts, the discovery of Anderson localization in random lasers provides a plausible route to resolve the difficulties, which enables one to tailor the number of lasing modes and stabilize the emission spectra. However, the related studies are rather rare and only restricted to limited wavelengths. In this study, based on enhanced Anderson localization assisted by surface plasmon resonance, spectrally stable deep-ultraviolet lasing action in AlGaN multiple quantum wells (MQWs) is demonstrated. Our work serves as firm evidence to demonstrate the underlying mechanism of stabilized deep-ultraviolet random laser action that multiple scattering of a light beam in a disordered medium can induce Anderson localization similar to electron behavior. This feature covers the whole spectral range, and it is a universal phenomenon of an electromagnetic wave. Notably, stabilized deep-ultraviolet random laser action has not been demonstrated in all previous studies, even though it has great academic interest and potential application in many areas from environmental protection to biomedical engineering.
An integrated random laser based on green materials with dissolubility and recyclability is created and demonstrated. The dissolvable and recyclable random laser (DRRL) can be dissolved in water, ...accompanying the decay of emission intensity and the increment in lasing threshold. Furthermore, the DRRL can be reused after the process of deionized treatment, exhibiting excellent reproducibility with several recycling processes.
The spectral specificity of deep-ultraviolet (UV) photodetectors makes them useful in many fields, spanning from disinfection of various surfaces and water purification to optical communication. As ...silicon-based devices show obvious disadvantages as UV devices because of their low band gap, semiconductor materials with a wide band gap exceeding 4 eV serve as excellent alternatives. In this paper, by the integration of the unique properties of each constituent material, we design a nanolayered graphene/insulator/semiconductor (graphene/hBN/n-AlGaN) deep-UV photodetector with high performance. The wide-band gap AlGaN semiconductor enables the detection of deep-UV signals without the requirement of a UV-pass filter and thus acts as a true solar-blind photodetector. In addition, the several nanolayered graphene–hBN heterostructure is utilized to enhance the performance of photodetectors, which successfully solves the strain issue between graphene and the conventional bulk insulators. Besides, the high transparency of graphene can enable incident light to directly excite the active layer with negligible optical loss, and the two-dimensional hBN insulator is beneficial to reduce dark current and assist the quantum tunneling of photogenerated carriers. Interestingly, the photodetectors demonstrated in this work show the highest responsivity and detectivity compared with previously reported AlGaN-based deep-UV photodetectors.
MoS
quantum dots (QDs)-based white-light-emitting diodes (QD-WLEDs) are designed, fabricated, and demonstrated. The highly luminescent, histidine-doped MoS
QDs synthesized by microwave induced ...fragmentation of 2D MoS
nanoflakes possess a wide distribution of available electronic states as inferred from the pronounced excitation-wavelength-dependent emission properties. Notably, the histidine-doped MoS
QDs show a very strong emission intensity, which exceeds seven times of magnitude larger than that of pristine MoS
QDs. The strongly enhanced emission is mainly attributed to nitrogen acceptor bound excitons and passivation of defects by histidine-doping, which can enhance the radiative recombination drastically. The enabled electroluminescence (EL) spectra of the QD-WLEDs with the main peak around 500 nm are found to be consistent with the photoluminescence spectra of the histidine-doped MoS
QDs. The enhanced intensity of EL spectra with the current increase shows the stability of histidine-doped MoS
based QD-WLEDs. The typical EL spectrum of the novel QD-WLEDs has a Commission Internationale de l'Eclairage chromaticity coordinate of (0.30, 0.36) exhibiting an intrinsic broadband white-light emission. The unprecedented and low-toxicity QD-WLEDs based on a single light-emitting material can serve as an excellent alternative for using transition metal dichalcogenides QDs as next generation optoelectronic devices.
Light emitting diodes (LEDs) are ubiquitous in our daily life nowadays. Among them, ultraviolet LEDs are unique because of their wide range of potential applications, spanning from biomedicine, ...environmental protection to public health. However, fabricating highly efficient and cost-effective ultraviolet LEDs still remains as a great challenge. In this work, a graphene–insulator–semiconductor (GIS) ultraviolet LED based on the mechanism of quantum tunneling has been designed, fabricated, and demonstrated, which possesses state-of-the-art multi-purposes, including electroluminescence, outstanding detection performance, and economical fabrication processes. The GIS ultraviolet device consists of an AlGaN thin film, a SiO2 insulating layer, and a graphene transparent electrode. Under a forward bias, the electroluminescence can be induced by the recombination of hole tunneling from graphene into the valence band edge of n-AlGaN and electrons in the conduction band with a high emission efficiency exceeding 10%. In addition, our GIS ultraviolet LEDs show an excellent ultraviolet-detecting capability and dual-side light emission, which can be used in optical communications and for the development of multifunctional optoelectronic devices. Notably, unlike the conventional LEDs, which requires both p-type and n-type doping of a semiconductor, the developed approach shown here only needs one type of doping. This approach can be applied to many other semiconductors with the inherent difficulty of both type of doping.
Deep learning and analysis of heavy metal concentration are very crucial to our life, for it plays an essential role in both environmental and human health. In this paper, we developed a new Cu (II) ...ions sensor made by all organic material with bending and stretching properties. The new sensor consists of chlorophyll-a extracted from fresh leaves of Common Garcinia, plant fiber and with the use of PDMS as a substrate. Fluorescence spectra study shows that chlorophyll-a is significantly much more sensitive to Cu (II) ions than any other heavy metal ions and the device sensitivity outperforms all the Cu (II) ions sensors ever reported. The result fully shows the selectivity of chlorophyll-a toward Cu (II) ions. Bending and stretching tests show that the sensor has an outstanding durability, which can be used to develop accompanying applications, such as real-time sampling and the analysis of Cu (II) concentration specified in athlete’s sweat or patients with brain death and Parkinson’s disease.
碩士
國立交通大學
電信研究所
85
This paper investigates the application of multi-code SS-CDMA
techniquesto three-dimensional stereoscopic video transmission
over wireless ATM networks. 3D visual communications, ...made
through the use of stereoscopic images, are able toachieve total
display realism. Such services allow users to share the virtual
reality (VR)world without any geographical restrictions. In
order to create a 3D system with two images (left and right)
that should be transmitted over a bandlimited mobile
channelsimultaneously, a cost-effective MPEG-based wavelet
multiresolution coding with an joint motion- and disparity-
compensation is developed to reduce a large amount of
information contained in the images in order to the meet the low
transmission rate limitationof mobile channels. However, the
rapidly variable bit rate (VBR) characteristics of the MPEG-
based 3D videos seems a weakness to the transmission of such
videos via a constantbit-rate (CBR) mobile channel.The ATM
technique is especially wellsuited for
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