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Sa Cai, Xiaojie Xu, Wei Yang, Jiaxin Chen, Xiaosheng Fang
Photodetectors (PDs), as an indispensable component in electronics, are highly desired to be flexible to meet the trend of next-generation wearable electronics. Unfortunately, no in-depth reviews on the design strategies, material exploration, and potential applications of wearable photodetectors are found in literature to date. Thus, this progress report first summarizes the fundamental design principles of turning "hard" photodetectors "soft," including 2D (polymer and paper substrate-based devices) and 1D PDs (fiber shaped devices)...
February 20, 2019: Advanced Materials
Yayu Zhai, Ping Song, Xiaoxiao Chen
The photonic mixer device (PMD) solid-state array lidar, as a three-dimensional imaging technology, has attracted research attention in recent years because of its low cost, high frame rate, and high reliability. To address the disadvantages of traditional PMD solid-state array lidar calibration methods, including low calibration efficiency and accuracy, and serious human error factors, this paper first proposes a calibration method for an array complementary metal⁻oxide⁻semiconductor photodetector using a black-box calibration device and an electrical analog delay method; it then proposes a modular lens distortion correction method based on checkerboard calibration and pixel point adaptive interpolation optimization...
February 17, 2019: Sensors
Thi Tuyen Ngo, Ivan Mora-Seró
Colloidal Quantum Dots (QDs) have received an extensive attention during the last few decades due to their amazing properties emerging from the quantum confinement. In parallel, halide perovskites have attracted attention by the demonstration of very high performances especially in solar cell and LEDs, and other optoelectronic devices. Both families of materials can be prepared in a relatively simple way, facilitating their integration. There are several examples of their interaction enhancing the properties of the final nanocomposite...
February 19, 2019: Journal of Physical Chemistry Letters
Junze Li, Jun Wang, Jiaqi Ma, Hongzhi Shen, Lu Li, Xiangfeng Duan, Dehui Li
Filterless narrowband photodetectors can realize color discrimination without filter or bulk spectrometer, thus greatly reducing the system volume and cost for many imaging applications. Charge collection narrowing has been demonstrated to be a successful approach to achieve filterless narrowband photodetections; nevertheless, it sacrifices the sensitivity of the photodetectors. Here we show a highly tunable narrowband photodetector based on two-dimensional perovskite single crystals with high external quantum efficiency (200%), ultralow dark current (10-12  A), and high on-off ratio (103 )...
February 18, 2019: Nature Communications
Haowei Lin, Kai Chen, Mingke Li, Beibei Ji, Yaohui Jia, Xinyu Liu, Jinling Li, Weiqiang Song, Chunlong Guan
We demonstrate that a novel photodetector is constructed by CdS/PPV (poly(p-phenylene vinylene)) homogeneous hybrid nanowire arrays via a simple template-assisted electrochemical co-deposition approach. Owing to the well-matched energy levels between CdS and PPV, the recombination of photogenerated electrons and holes in CdS/PPV hybrid nanowire arrays is greatly inhibited. It is found that the homogeneous hybrid nanowire arrays exhibit remarkably enhanced photoelectric response and the ON/OFF ratio by 17 times compared to individual CdS component...
February 19, 2019: ACS Applied Materials & Interfaces
Guigen Liu, Ming Han
We propose and demonstrate the use of laser intensity modulation for the multiplexing and demultiplexing of fiber Bragg grating-based ultrasound sensors. The method utilizes an intensity modulator to modulate the output power of the laser with a frequency much higher than that of the ultrasounds. The high-frequency-modulated optical signal serves as a carrier signal. Ultrasonic signals impinged onto the sensor appear as the envelope of the carrier signal. In the frequency domain, the carrier signal and the sidebands encoded with the ultrasonic signal are separated from those of other channels and, thus, can be isolated using an electronic bandpass filter for crosstalk-free ultrasound detection...
February 15, 2019: Optics Letters
Min Cao, Cong Zhang, Zhi Cai, Chengcheng Xiao, Xiaosong Chen, Kongyang Yi, Yingguo Yang, Yunhao Lu, Dacheng Wei
Owing to strong light-matter interaction, two-dimensional (2D) organic crystal is regarded as promising materials for ultrasensitive photodetectors, however it still received limited success due to degraded photoelectrical response and problems in controllable growth. Here, we find the growth of 2D organic crystal obeys Gibbs-Curie-Wulff law, and develop a seed-epitaxial drop-casting method to grow millimeter-sized 1,4-bis(4-methylstyryl)benzene 2D crystals on SiO2 /Si in a thermodynamically controlled process...
February 14, 2019: Nature Communications
Wenjun Chen, Joshua Castro, Seungbae Ahn, Xiaochen Li, Oscar Vazquez-Mena
Charge collection is critical in any photodetector or photovoltaic device. Novel materials such as quantum dots (QDs) have extraordinary light absorption properties, but their poor mobility and short diffusion length limit efficient charge collection using conventional top/bottom contacts. In this work, a novel architecture based on multiple intercalated chemical vapor deposition graphene monolayers distributed in an orderly manner inside a QD film is studied. The intercalated graphene layers ensure that at any point in the absorbing material, photocarriers will be efficiently collected and transported...
February 13, 2019: Advanced Materials
Muhammad Ahsan Iqbal, Cui Menghua, Adeel Liaqat, Rakba Faiz, Mongur Hossain, Xinsheng Wang, Sabir Hussain, Dang Chunhe, Liu Haining, Wen Wen, Wu Juanxia, Liming Xie
Photodetectors have widespread applications in telecommunication, thermal imaging, bio-medical imaging and so on. Photogating effect, arising from charge trapping at defects and/or interfaces, can have extremely high photoelectric gain, which can benefit to high-sensitivity room temperature photodetection. Here, we introduce thin layered organic CPXs integrated on graphene transistors for the development of hybrid phototransistors with ultra-high photoresponsivity of ~106 A/W in near infrared (NIR) region at room temperature...
February 11, 2019: Nanotechnology
Guofeng Yang, Yan Gu, Pengfei Yan, Jin Wang, Junjun Xue, Xiumei Zhang, Naiyan Lu, Guoqing Chen
Vertically oriented multi-layered MoS2 nanosheets were successfully grown on p-GaN nanorod substrate using chemical vapor deposition (CVD) method. The p-GaN nanorod substrate was fabricated by dry etching employing self-assembled nickel (Ni) nanopartical as mask. Photoluminescence (PL) and Raman characterizations demonstrate the multi-layered structure of MoS2 nanosheet growth on p-GaN nanorods as compared with the referential monolayer MoS2 on GaN wafer substrate under the same growth procedure. The growth model of vertical MoS2 nanosheet formed on GaN nanorods is evidently proposed according to the first-principle calculations...
February 11, 2019: ACS Applied Materials & Interfaces
Seong Heon Kim, Jooho Lee, Eunae Cho, Junho Lee, Dong-Jin Yun, Dongwook Lee, Yongsung Kim, Takkyun Ro, Chul-Joon Heo, Gae Hwang Lee, Yong Wan Jin, Sunghan Kim, Kyung-Bae Park, Sung Heo
Controlling defect states in a buffer layer for organic photo devices is one of the vital factors which have great influence on the device performance. Defect states in silicon oxynitride (SiOx Ny ) buffer layer for organic photo devices can be controlled by introducing appropriate dopant materials. We performed ab initio simulations to identify the effect on doping SiOx Ny with carbon (C), boron (B), and phosphorous (P) atoms. The results unveil that hole defects in the SiOx Ny layer diminish with the phosphorous doping...
February 11, 2019: Scientific Reports
Jung Han Kim, Tae-Jun Ko, Emmanuel Okogbue, Sang Sub Han, Mashiyat Sumaiya Shawkat, Md Golam Kaium, Kyu Hwan Oh, Hee-Suk Chung, Yeonwoong Jung
Two-dimensional (2D) transition metal dichalcogenide (2D TMD) layers present an unusually ideal combination of excellent opto-electrical properties and mechanical tolerance projecting high promise for a wide range of emerging applications, particularly in flexible and stretchable devices. The prerequisite for realizing such opportunities is to reliably integrate large-area 2D TMDs of well-defined dimensions on mechanically pliable materials with targeted functionalities by transferring them from rigid growth substrates...
February 7, 2019: Scientific Reports
Seyed Ehsan Jamali Mahabadi, Shaokang Wang, Thomas F Carruthers, Curtis R Menyuk, Franklyn J Quinlan, Meredith N Hutchinson, Jason D McKinney, Keith J Williams
We describe a procedure to calculate the impulse response and phase noise of high-current photodetectors using the drift-diffusion equations while avoiding computationally expensive Monte Carlo simulations. We apply this procedure to a modified uni-traveling-carrier (MUTC) photodetector. In our approach, we first use the full drift-diffusion equations to calculate the steady-state photodetector parameters. We then perturb the generation rate as a function of time to calculate the impulse response. We next calculate the fundamental shot noise limit and cut-off frequency of the device...
February 4, 2019: Optics Express
Fei Hu, Xi-Yuan Dai, Zhi-Quan Zhou, Xiang-Yang Kong, Shu-Lin Sun, Rong-Jun Zhang, Song-You Wang, Ming Lu, Jian Sun
Sub-bandgap near-infrared silicon (Si) photodetectors are key elements in integrated Si photonics. We demonstrate such a Si photodetector based on a black Si (b-Si)/Ag nanoparticles (Ag-NPs) Schottky junction. This photodetector synergistically employs the mechanisms of inner photoemission, light-trapping, and surface-plasmon-enhanced absorption to efficiently absorb the sub-bandgap light and generate a photocurrent. The b-Si/Ag-NPs sample was prepared by means of wet chemical etching. Compared to those of a planar-Si/Ag thin-film Schottky photodetector, the responsivities of the b-Si/Ag-NPs photodetector were greatly enhanced, being 0...
February 4, 2019: Optics Express
Han Liu, Xiangfeng Wei, Zhixiang Zhang, Xunyong Lei, Wenchao Xu, Linbao Luo, Hualing Zeng, Ruifeng Lu, Jiehua Liu
We report a new suspension method to obtain the cubic MAPbBr3 single crystal with a concave surface for the first time. The cubic MAPbBr3 crystal with micro-concavity possesses the good crystallinity and carrier lifetime. The excellent photoelectric performance was provided by the concave based MAPbBr3 photodetectors due to the good light trapping and shortened carrier pathway. As a result, the concave-based photodetector exhibits the superior responsivity of 62.9 A W-1 and 5.43 A W-1 and EQE of 1.50×104% and 1...
February 6, 2019: Journal of Physical Chemistry Letters
Jinwu Park, Geonwook Yoo, Junseok Heo
Notable progress achieved in studying MoS2 based phototransistors reveals the great potential to be applicable in various field of photodetectors, and to further expand it, a durability study of MoS2 phototransistors in harsh environments is highly required. Here, we investigate effects of gamma rays on the characteristics of MoS2 phototransistors and improve its radiation hardness by incorporating CdSe/ZnS quantum dots as an encapsulation layer. A 73.83% decrease in the photoresponsivity was observed after gamma ray irradiation of 400 Gy, and using a CYTOP and CdSe/ZnS quantum dot layer, the photoresponsivity was successfully retained at 75...
February 5, 2019: Scientific Reports
Sohail Abbas, Mohit Kumar, Dong-Wook Kim, Joondong Kim
ZnO is a potential candidate for photodetection utilizing the pyroelectric effect. Here, a self-biased and translucent photodetector with the configuration of Cu4 O3 /ZnO/FTO/Glass is designed and fabricated. In addition, the pyroelectric effect is effectively harvested using indium tin oxide (ITO), silver nanowires (AgNWs), and a blend of AgNWs-coated ITO as the transparent selective contact electrode. The improved rise times are observed from 1400 µs (bare condition; without the selective electrode) to 69, 60, 7 µs, and fall times from 720 µs (bare condition) to 80, 70, 10 µs for corresponding ITO, AgNWs, and AgNWs-coated ITO contact electrodes, respectively...
February 5, 2019: Small
Tao Zhu, Luyao Zheng, Xiang Yao, Lei Liu, Fei Huang, Yong Cao, Xiong Gong
Broadband photodetectors have important applications in both scientific and industrial sectors. In this study, we report room-temperature operated solution-processed photodetectors by PbSe quantum dots (QDs) with spectral response from 350 nm to 2500 nm. In order to boost both external quantum efficiency (EQE) and projected detectivity (D*), the hole-trap assisted photomultiplication effect through EDT-PbSe QDs/TABI PbSe QDs double-thin-layer thin film, where EDT-PbSe QDs is 1, 2-ethanedithiol (EDT) capped PbSe QDs and TABI-PbSe QDs is tetrabutylammonium (TABI) capped PbSe QDs, is applied...
February 5, 2019: ACS Applied Materials & Interfaces
Liyang Xiang, Antoine Harel, HongYing Gao, Anthony E Pickering, Susan J Sara, Sidney I Wiener
The nucleusLocus Coeruleus (LC) is the major source of forebrain norepinephrine. LC is implicated in arousal, response to novelty, and cognitive functions, including decision-making and behavioral flexibility. One hypothesis is that LC activation promotes rapid shifts in cortical attentional networks following changes in environmental contingencies. Recent recordings further suggest LC is critical for mobilizing resources to deal with challenging situations. In the present study optogenetically identified LC neuronal activity was recorded in rats in a self-paced T-maze...
February 4, 2019: Scientific Reports
Dong Jin Lee, G Mohan Kumar, P Ilanchezhiyan, Fu Xiao, Sh U Yuldashev, Yong Deuk Woo, Deuk Young Kim, Tae Won Kang
In this paper, a photodetector based on arrayed CdTe microdots was fabricated on Bi coated transparent conducting indium tin oxide (ITO)/glass substrates. Current-voltage characteristics of these photodetectors revealed an ultrahigh sensitivity under stress (in the form of force through press) while compared to normal condition. The devices exhibited excellent photosensing properties with photoinduced current increasing from 20 to 76 μA cm-2 under stress. Furthermore, the photoresponsivity of the devices also increased under stress from 3...
February 1, 2019: Nanomaterials
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