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Kumar D, Li H, Kumbhar DD, Rajbhar MK, Das UK, Syed AM, Melinte G, El-Atab N. Highly Efficient Back-End-of-Line Compatible Flexible Si-Based Optical Memristive Crossbar Array for Edge Neuromorphic Physiological Signal Processing and Bionic Machine Vision. NANO-MICRO LETTERS 2024; 16:238. [PMID: 38976105 PMCID: PMC11231128 DOI: 10.1007/s40820-024-01456-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 06/11/2024] [Indexed: 07/09/2024]
Abstract
The emergence of the Internet-of-Things is anticipated to create a vast market for what are known as smart edge devices, opening numerous opportunities across countless domains, including personalized healthcare and advanced robotics. Leveraging 3D integration, edge devices can achieve unprecedented miniaturization while simultaneously boosting processing power and minimizing energy consumption. Here, we demonstrate a back-end-of-line compatible optoelectronic synapse with a transfer learning method on health care applications, including electroencephalogram (EEG)-based seizure prediction, electromyography (EMG)-based gesture recognition, and electrocardiogram (ECG)-based arrhythmia detection. With experiments on three biomedical datasets, we observe the classification accuracy improvement for the pretrained model with 2.93% on EEG, 4.90% on ECG, and 7.92% on EMG, respectively. The optical programming property of the device enables an ultra-low power (2.8 × 10-13 J) fine-tuning process and offers solutions for patient-specific issues in edge computing scenarios. Moreover, the device exhibits impressive light-sensitive characteristics that enable a range of light-triggered synaptic functions, making it promising for neuromorphic vision application. To display the benefits of these intricate synaptic properties, a 5 × 5 optoelectronic synapse array is developed, effectively simulating human visual perception and memory functions. The proposed flexible optoelectronic synapse holds immense potential for advancing the fields of neuromorphic physiological signal processing and artificial visual systems in wearable applications.
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Affiliation(s)
- Dayanand Kumar
- Smart, Advanced Memory Devices and Applications (SAMA) Laboratory, Electrical and Computer Engineering, Computer Electrical Mathematical Science and Engineering, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia
| | - Hanrui Li
- Smart, Advanced Memory Devices and Applications (SAMA) Laboratory, Electrical and Computer Engineering, Computer Electrical Mathematical Science and Engineering, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia
| | - Dhananjay D Kumbhar
- Smart, Advanced Memory Devices and Applications (SAMA) Laboratory, Electrical and Computer Engineering, Computer Electrical Mathematical Science and Engineering, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia
| | - Manoj Kumar Rajbhar
- Smart, Advanced Memory Devices and Applications (SAMA) Laboratory, Electrical and Computer Engineering, Computer Electrical Mathematical Science and Engineering, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia
| | - Uttam Kumar Das
- Smart, Advanced Memory Devices and Applications (SAMA) Laboratory, Electrical and Computer Engineering, Computer Electrical Mathematical Science and Engineering, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia
| | - Abdul Momin Syed
- Smart, Advanced Memory Devices and Applications (SAMA) Laboratory, Electrical and Computer Engineering, Computer Electrical Mathematical Science and Engineering, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia
| | - Georgian Melinte
- Smart, Advanced Memory Devices and Applications (SAMA) Laboratory, Electrical and Computer Engineering, Computer Electrical Mathematical Science and Engineering, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia
| | - Nazek El-Atab
- Smart, Advanced Memory Devices and Applications (SAMA) Laboratory, Electrical and Computer Engineering, Computer Electrical Mathematical Science and Engineering, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia.
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Liu M, Jiang M, Zhao Q, Tang K, Sha S, Li B, Kan C, Shi DN. Ultraviolet Exciton-Polariton Light-Emitting Diode in a ZnO Microwire Homojunction. ACS APPLIED MATERIALS & INTERFACES 2023; 15:13258-13269. [PMID: 36866718 DOI: 10.1021/acsami.2c19806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Low-dimensional ZnO, possessing well-defined side facets and optical gain properties, has emerged as a promising material to develop ultraviolet coherent light sources. However, the realization of electrically driven ZnO homojunction luminescence and laser devices is still a challenge due to the absence of a reliable p-type ZnO. Herein, the sample of p-type ZnO microwires doped by Sb (ZnO:Sb MWs) was synthesized individually. Subsequently, the p-type conductivity was examined using a single-MW field-effect transistor. Upon optical pumping, a ZnO:Sb MW showing a regular hexagonal cross-section and smooth sidewall facets can feature as an optical microcavity, which is evidenced by the achievement of whispering-gallery-mode lasing. By combining an n-type ZnO layer, a single ZnO:Sb MW homojunction light-emitting diode (LED), which exhibited a typical ultraviolet emission at a wavelength of 379.0 nm and a line-width of approximately 23.5 nm, was constructed. We further illustrated that strong exciton-photon coupling can occur in the as-constructed p-ZnO:Sb MW/n-ZnO homojunction LED by researching spatially resolved electroluminescence spectra, contributing to the exciton-polariton effect. Particularly, varying the cross-sectional dimensions of ZnO:Sb wires can further modulate the exciton-photon coupling strengths. We anticipate that the results can provide an effective exemplification to realize reliable p-type ZnO and tremendously promote the development of low-dimensional ZnO homojunction optoelectronic devices.
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Affiliation(s)
- Maosheng Liu
- College of Physics, MIIT Key Laboratory of Aerospace Information Materials and Physics, Key Laboratory for Intelligent Nano Materials and Devices, Nanjing University of Aeronautics and Astronautics, No. 29 Jiangjun Road, Nanjing 211106, China
| | - Mingming Jiang
- College of Physics, MIIT Key Laboratory of Aerospace Information Materials and Physics, Key Laboratory for Intelligent Nano Materials and Devices, Nanjing University of Aeronautics and Astronautics, No. 29 Jiangjun Road, Nanjing 211106, China
| | - Qinzhi Zhao
- College of Physics, MIIT Key Laboratory of Aerospace Information Materials and Physics, Key Laboratory for Intelligent Nano Materials and Devices, Nanjing University of Aeronautics and Astronautics, No. 29 Jiangjun Road, Nanjing 211106, China
| | - Kai Tang
- College of Physics, MIIT Key Laboratory of Aerospace Information Materials and Physics, Key Laboratory for Intelligent Nano Materials and Devices, Nanjing University of Aeronautics and Astronautics, No. 29 Jiangjun Road, Nanjing 211106, China
| | - Shulin Sha
- College of Physics, MIIT Key Laboratory of Aerospace Information Materials and Physics, Key Laboratory for Intelligent Nano Materials and Devices, Nanjing University of Aeronautics and Astronautics, No. 29 Jiangjun Road, Nanjing 211106, China
| | - Binghui Li
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
| | - Caixia Kan
- College of Physics, MIIT Key Laboratory of Aerospace Information Materials and Physics, Key Laboratory for Intelligent Nano Materials and Devices, Nanjing University of Aeronautics and Astronautics, No. 29 Jiangjun Road, Nanjing 211106, China
| | - Da Ning Shi
- College of Physics, MIIT Key Laboratory of Aerospace Information Materials and Physics, Key Laboratory for Intelligent Nano Materials and Devices, Nanjing University of Aeronautics and Astronautics, No. 29 Jiangjun Road, Nanjing 211106, China
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Ahmad M, Ahmad MK, Mamat MH, Mohamed A, Suriani AB, Ismail NMAN, Soon CF, Nafarizal N. Effects of Group-I Elements on Output Voltage Generation of ZnO Nanowires Based Nanogenerator; Degradation of Screening Effects by Oxidation of Nanowires. MICROMACHINES 2022; 13:1450. [PMID: 36144073 PMCID: PMC9503292 DOI: 10.3390/mi13091450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 07/11/2022] [Accepted: 07/20/2022] [Indexed: 06/16/2023]
Abstract
Here, we report the successful incorporation of group I elements (K, Na, Li) to ZnO nanowires. Three distinct (2, 4, and 6 wt.%) doping concentrations of group I elements have been used to generate high piezoelectric voltage by employing a vertically integrated nanowire generator (VING) structure. X-ray photoelectron spectra (XPS) indicated the seepage of dopants in ZnO nanowires by substitution of Zn. Shallow acceptor levels (LiZn, NaZn, KZn) worked as electron trapping centers for intrinsically n-type ZnO nanowires. Free moving electrons caused a leakage current through the nanowires and depleted their piezoelectric potential. Reverse leakage current is a negative factor for piezoelectric nanogenerators. A reduction in reverse leakage current signifies the rise in output voltage. A gradual rise in output voltage has been witnessed which was in accordance with various doping concentrations. K-doped ZnO nanowires have generated voltages of 0.85 V, 1.48 V, and 1.95 V. For Na-doped ZnO nanowires, the voltages were 1.23 V, 1.73 V, and 2.34 V and the voltages yeilded for Li-doped ZnO nanowires were 1.87 V, 2.63 V, and 3.54 V, respectively. Maximum voltage range has been further enhanced by the surface enrichment (oxidized with O2 molecules) of ZnO nanowires. Technique has been opted to mitigate the screening effect during an external stress. After 5 h of oxidation in a sealed chamber at 100 ppm, maximum voltage peaks were pronounced to 2.48 V, 3.19 V, and 4.57 V for K, Na, and Li, respectively. A low-cost, high performance mechanical transducer is proposed for self-powered devices.
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Affiliation(s)
- Mansoor Ahmad
- Microelectronic and Nanotechnology—Shamsuddin Research Centre (MiNT-SRC), Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), Parit Raja 86400, Malaysia
| | - M. K. Ahmad
- Microelectronic and Nanotechnology—Shamsuddin Research Centre (MiNT-SRC), Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), Parit Raja 86400, Malaysia
| | - M. H. Mamat
- NANO-ElecTronic Centre (NET), School of Electrical Engineering, College of Engineering, Universiti Teknologi MARA, Shah Alam 40450, Malaysia
| | - A. Mohamed
- Nanotechnology Research Centre, Department of Physic, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim 35900, Malaysia
| | - A. B. Suriani
- Nanotechnology Research Centre, Department of Physic, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim 35900, Malaysia
| | - N. M. A. N. Ismail
- Microelectronic and Nanotechnology—Shamsuddin Research Centre (MiNT-SRC), Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), Parit Raja 86400, Malaysia
| | - C. F. Soon
- Microelectronic and Nanotechnology—Shamsuddin Research Centre (MiNT-SRC), Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), Parit Raja 86400, Malaysia
| | - N. Nafarizal
- Microelectronic and Nanotechnology—Shamsuddin Research Centre (MiNT-SRC), Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), Parit Raja 86400, Malaysia
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Baek SD, Kwon DK, Kim YC, Myoung JM. Violet Light-Emitting Diodes Based on p-CuI Thin Film/n-MgZnO Quantum Dot Heterojunction. ACS APPLIED MATERIALS & INTERFACES 2020; 12:6037-6047. [PMID: 31985209 DOI: 10.1021/acsami.9b18507] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
As the lighting technology evolves, the need for violet light-emitting diodes (LEDs) is growing for high color rendering index lighting. The present technology for violet LEDs is based on the high-cost GaN materials and metal-organic chemical vapor deposition process; therefore, there have recently been intensive studies on developing low-cost alternative materials and processes. In this study, for the first time, we demonstrated violet LEDs based on low-cost materials and processes using a p-CuI thin film/n-MgZnO quantum dot (QD) heterojunction. The p-CuI thin film layer was prepared by an iodination process of Cu films, and the n-MgZnO layer was deposited by spin-coating presynthesized n-MgZnO QDs. To maximize the performance of the violet LED, an optimizing process was performed for each layer of p- and n-type materials. The optimized LED with 1 × 1 mm2-area pixel fabricated using the p-CuI thin film at the iodination temperature of 15 °C and the n-MgZnO QDs at the Mg alloying concentration of 2.7 at. % exhibited the strongest violet emissions at 6 V.
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Affiliation(s)
- Sung-Doo Baek
- Department of Materials Science and Engineering , Yonsei University , 50 Yonsei-ro , Seodaemun-gu, Seoul 03722 , Republic of Korea
| | - Do-Kyun Kwon
- Department of Materials Science and Engineering , Yonsei University , 50 Yonsei-ro , Seodaemun-gu, Seoul 03722 , Republic of Korea
| | - Yun Cheol Kim
- Department of Materials Science and Engineering , Yonsei University , 50 Yonsei-ro , Seodaemun-gu, Seoul 03722 , Republic of Korea
| | - Jae-Min Myoung
- Department of Materials Science and Engineering , Yonsei University , 50 Yonsei-ro , Seodaemun-gu, Seoul 03722 , Republic of Korea
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Su M, Zhang T, Su J, Wang Z, Hu Y, Gao Y, Gu H, Zhang X. Homogeneous ZnO nanowire arrays p-n junction for blue light-emitting diode applications. OPTICS EXPRESS 2019; 27:A1207-A1215. [PMID: 31510509 DOI: 10.1364/oe.27.0a1207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 07/03/2019] [Indexed: 06/10/2023]
Abstract
ZnO is a promising short-wavelength light-emitting materials for its wide bandgap (3.37 eV) and large exciton binding energy (∼60 meV), however, practical p-type doped ZnO is the main challenge in this field. Here, Blue light-emitting diodes (LEDs) based on the homogeneous junctions of Sb doped ZnO nanowire arrays grown on Ga doped ZnO single crystal substrate are fabricated. Element analysis, FET and Hall-effect measurements demonstrate that the Sb atom has been successfully doped into ZnO nanowires to from p-type conductivity. On the benefit of high quality of nano-size homojunction, the fabricated LED shows low turn-on voltage turn-on voltage as low as 3.4 V and strong blue emission peak located at 425 nm at room temperature, which originate from interfacial recombination of ZnO nanowire p-n homojunctions. The present blue LED based on ZnO material may have potential applications in short-wavelength optoelectronic devices.
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Shi L, Du L, Xu Y, Jin L, Zhang H, Li Y, Ma X, Zou Y, Zhao D. Morphology and electrical characteristics of p-type ZnO microwires with zigzag rough surfaces induced by Sb doping. RSC Adv 2018; 8:35023-35030. [PMID: 35547043 PMCID: PMC9087441 DOI: 10.1039/c8ra07135g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 10/03/2018] [Indexed: 11/21/2022] Open
Abstract
Sb-doped p-type ZnO microwires with zigzag rough surfaces were synthesized by two zone chemical vapor deposition. The zigzag morphology characteristics analyzed by high resolution scanning electron microscopy and transmission electron microscopy show the existence of surface defects caused by Sb doping. The incorporation of Sb into a ZnO lattice induces lattice imperfection, which is the origin of the zigzag rough surface. Photoluminescence and electrical properties of the obtained Sb-doped ZnO microwires were determined. The crossed structure microwire-based p-n homojunction device was fabricated by applying as-synthesized Sb-doped p-type ZnO microwires and undoped n-type ZnO microwires. The doped microwires demonstrate reproducible p-type conduction and enhanced rectifying behavior with increasing Sb doping concentration. The results demonstrated that the optimizable optical and electrical characteristics, controlled by increasing the doping concentration, are reflected in the surface morphology changes which would be helpful for characterizing the doping effects in micro/nanoscale materials.
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Affiliation(s)
- Linlin Shi
- State Key Laboratory of High Power Semiconductor Laser, Changchun University of Science and Technology No. 7186 Wei-Xing Road Changchun 130022 People's Republic of China +86-85583395 +86-85583395
| | - Luchao Du
- Institute of Atomic and Molecular Physics, Jilin University No. 2699 Qian-Jin Road Changchun 130012 People's Republic of China
| | - Yingtian Xu
- State Key Laboratory of High Power Semiconductor Laser, Changchun University of Science and Technology No. 7186 Wei-Xing Road Changchun 130022 People's Republic of China +86-85583395 +86-85583395
| | - Liang Jin
- State Key Laboratory of High Power Semiconductor Laser, Changchun University of Science and Technology No. 7186 Wei-Xing Road Changchun 130022 People's Republic of China +86-85583395 +86-85583395
| | - He Zhang
- State Key Laboratory of High Power Semiconductor Laser, Changchun University of Science and Technology No. 7186 Wei-Xing Road Changchun 130022 People's Republic of China +86-85583395 +86-85583395
| | - Yan Li
- State Key Laboratory of High Power Semiconductor Laser, Changchun University of Science and Technology No. 7186 Wei-Xing Road Changchun 130022 People's Republic of China +86-85583395 +86-85583395
| | - Xiaohui Ma
- State Key Laboratory of High Power Semiconductor Laser, Changchun University of Science and Technology No. 7186 Wei-Xing Road Changchun 130022 People's Republic of China +86-85583395 +86-85583395
| | - Yonggang Zou
- State Key Laboratory of High Power Semiconductor Laser, Changchun University of Science and Technology No. 7186 Wei-Xing Road Changchun 130022 People's Republic of China +86-85583395 +86-85583395
| | - Dongxu Zhao
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences No. 3888 Dongnanhu Road Changchun 130033 People's Republic of China
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Kwon DK, Porte Y, Ko KY, Kim H, Myoung JM. High-Performance Flexible ZnO Nanorod UV/Gas Dual Sensors Using Ag Nanoparticle Templates. ACS APPLIED MATERIALS & INTERFACES 2018; 10:31505-31514. [PMID: 30133251 DOI: 10.1021/acsami.8b13046] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Flexible zinc oxide (ZnO) nanorod (NR) ultraviolet (UV)/gas dual sensors using silver (Ag) nanoparticle (NP) templates were successfully fabricated on a polyimide substrate with nickel electrodes. Arrays of Ag NPs were used as a template for the growth of ZnO NRs, which could enhance the flexibility and the sensing properties of the devices through the localized surface plasmon resonance (LSPR) effect. The Ag NPs were fabricated by the rapid thermal annealing process of Ag thin films, and ZnO NRs were grown on Ag NPs to maximize the surface area and form networks with rod-to-rod contacts. Because of the LSPR effect by Ag NPs, the UV photoresponse of the ZnO NRs was amplified and the depletion region of ZnO NRs was formed quickly because of the Schottky contact with the Ag NPs. As a consequence, ZnO NR UV/gas dual sensors grown on the Ag NP template with a diameter of 28 nm exhibited the outstanding UV-sensing characteristics with a UV on-off ratio of 3628 and a rising time ( tr) and a decay time ( td) of 3.52 and 0.33 s upon UV exposure, along with excellent NO2-sensing characteristics with a stable gas on-off ratio of 288.5 and a tr and td of 38 and 62 s upon NO2 exposure. Furthermore, the sensors grown on the Ag NP template exhibited good mechanical flexibility and stable sensing properties without significant degradation even after the bending test up to 10 000 cycles at the bending radius of 5 mm.
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Pang X, Cui C, Su M, Wang Y, Wei Q, Tan W. Construction of self-powered cytosensing device based on ZnO nanodisks@g-C 3N 4 quantum dots and application in the detection of CCRF-CEM cells. NANO ENERGY 2018; 46:101-109. [PMID: 30271703 PMCID: PMC6157620 DOI: 10.1016/j.nanoen.2018.01.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We herein report a self-powered and renewable cytosensing device based on ZnO nanodisks(NDs)@g-C3N4 quantum dots. The device features enhanced photoelectrochemical (PEC) activity compared to ZnO NDs or g-C3N4 QDs alone. The enhanced PEC ability is attributed to the synergistic effect of the high visible light sensitivity of g-C3N4 QDs and the staggered band alignment heterojunction structure with suitable band offset, which affords higher photoelectron transfer and separation efficiency. In addition, the hybridization of g-C3N4 QDs further accelerates interfacial electron transfer and blocks recombination between electron donors and photo-generated holes. The device was applied to the detection of CCRF-CEM cells. By conjugation to Sgc8c aptamer, which preferentially interacts with membrane-bound PTK7 on CCRF-CEM membranes, capture of target CCRF-CEM cells resulted in a decrease in apparent power output, which was then exploited for the ultrasensitive detection of the target cells. This decrease in power output can be recovered by simply increasing the temperature to release the cells, thus recycling the cytosensing performance. The device displayed a linear relationship between the change of power output and the logarithm of the cell concentration from 20 to 20,000 cell/mL (R2 = 0.9837) and a detection limit down to 20 cell/mL, as well as excellent selectivity and reproducibility. Thus, this ZnO NDs@g-C3N4 QDs-based device exhibits high potential for the detection of CCRF-CEM cells.
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Affiliation(s)
- Xuehui Pang
- Key Laboratory of Interfacial Reaction & Sensing Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan, Shandong 250022, People’s Republic of China
- Center for Research at the Bio/nano Interface, Department of Chemistry and Department of Physiology and Functional Genomics, UF Genetics Institute and McKnight Brain Institute, Shands Cancer Center, University of Florida, Gainesville, FL 32611-7200, United States
| | - Cheng Cui
- Center for Research at the Bio/nano Interface, Department of Chemistry and Department of Physiology and Functional Genomics, UF Genetics Institute and McKnight Brain Institute, Shands Cancer Center, University of Florida, Gainesville, FL 32611-7200, United States
| | - Minhui Su
- Key Laboratory of Interfacial Reaction & Sensing Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan, Shandong 250022, People’s Republic of China
| | - Yaoguang Wang
- Key Laboratory of Interfacial Reaction & Sensing Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan, Shandong 250022, People’s Republic of China
| | - Qin Wei
- Key Laboratory of Interfacial Reaction & Sensing Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan, Shandong 250022, People’s Republic of China
| | - Weihong Tan
- Center for Research at the Bio/nano Interface, Department of Chemistry and Department of Physiology and Functional Genomics, UF Genetics Institute and McKnight Brain Institute, Shands Cancer Center, University of Florida, Gainesville, FL 32611-7200, United States
- Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, People’s Republic of China
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Cho SR, Porte Y, Kim YC, Myoung JM. Effect of Nonionic Surfactant Additive in PEDOT:PSS on PFO Emission Layer in Organic-Inorganic Hybrid Light-Emitting Diode. ACS APPLIED MATERIALS & INTERFACES 2018; 10:9612-9619. [PMID: 29480008 DOI: 10.1021/acsami.7b19267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Poly(9,9-dioctylfluorene) (PFO) has attracted significant interests owing to its versatility in electronic devices. However, changes in its optical properties caused by its various phases and the formation of oxidation defects limit the application of PFO in light-emitting diodes (LEDs). We investigated the effects of the addition of Triton X-100 (hereinafter shortened as TX) in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to induce interlayer diffusion between PEDOT:PSS and PFO to enhance the stability of the PFO phase and suppress its oxidation. Photoluminescence (PL) measurement on PFO/TX-mixed PEDOT:PSS layers revealed that, upon increasing the concentration of TX in the PEDOT:PSS layer, the β phase of PFO could be suppressed in favor of the glassy phase and the wide PL emission centered at 535 nm caused by ketone defects formed by oxidation was decreased considerably. LEDs were then fabricated using PFO as an emission layer, TX-mixed PEDOT:PSS as hole-transport layer, and zinc oxide (ZnO) nanorods as electron-transport layer. As the TX concentration reached 3 wt %, the devices exhibited dramatic increases in current densities, which were attributed to the enhanced hole injection due to TX addition, along with a shift in the dominant emission wavelength from a green electroluminescence (EL) emission centered at 518 nm to a blue EL emission centered at 448 nm. The addition of TX in PEDOT:PSS induced a better hole injection in the PFO layer, and through interlayer diffusion, stabilized the glassy phase of PFO and limited the formation of oxidation defects.
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Affiliation(s)
- Seong Rae Cho
- Department of Materials Science and Engineering , Yonsei University , 50 Yonsei-ro , Seodaemun-gu, Seoul 03722 , Republic of Korea
| | - Yoann Porte
- Department of Materials Science and Engineering , Yonsei University , 50 Yonsei-ro , Seodaemun-gu, Seoul 03722 , Republic of Korea
| | - Yun Cheol Kim
- Department of Materials Science and Engineering , Yonsei University , 50 Yonsei-ro , Seodaemun-gu, Seoul 03722 , Republic of Korea
| | - Jae-Min Myoung
- Department of Materials Science and Engineering , Yonsei University , 50 Yonsei-ro , Seodaemun-gu, Seoul 03722 , Republic of Korea
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You D, Xu C, Qin F, Zhu Z, Manohari AG, Xu W, Zhao J, Liu W. Interface control for pure ultraviolet electroluminescence from nano-ZnO-based heterojunction devices. Sci Bull (Beijing) 2018; 63:38-45. [PMID: 36658916 DOI: 10.1016/j.scib.2017.12.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 11/14/2017] [Accepted: 11/28/2017] [Indexed: 01/21/2023]
Abstract
Realization of pure and stable ultraviolet electroluminescence (UV EL) of ZnO light-emitting diode (LED) is still a challenging issue, due to complicated defects of intrinsic ZnO and the corresponding device interfaces. In this paper, we demonstrated a simple & feasible method to fabricate n-ZnO/AlN/p-GaN heterojunctions light-emitting devices. First, the vertically aligned ZnO nanorods (NRs) have been prepared as high quality active layer, and the nanostructured heterojunction LED arrays were constructed by directly bonding ZnO NRs onto AlN-coated p-GaN wafer. By optimizing the AlN layer thickness to be 20 nm, a strong and pure ultraviolet emission located at 387 nm can be observed. The energy band alignment of n-ZnO/AlN (20 nm)/p-GaN heterojunction LED has been studied by using X-ray photoelectron spectroscopy (XPS), the valence band offset between AlN and GaN was calculated to be 0.34 eV. On the other side, the conduction band offset (as large as 3.28 eV) between AlN and ZnO can block the flow of electrons from ZnO to p-GaN. Thus, electron-hole recombination takes place in the ZnO layer, and a pure UV EL could be observed. Our results provide a significant approach toward future of pure ultraviolet optoelectronic LEDs.
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Affiliation(s)
- Daotong You
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Chunxiang Xu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China.
| | - Feifei Qin
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Zhu Zhu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - A Gowri Manohari
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Wei Xu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Jie Zhao
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Wei Liu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
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Kim JW, Porte Y, Ko KY, Kim H, Myoung JM. Micropatternable Double-Faced ZnO Nanoflowers for Flexible Gas Sensor. ACS APPLIED MATERIALS & INTERFACES 2017; 9:32876-32886. [PMID: 28882036 DOI: 10.1021/acsami.7b09251] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Micropatternable double-faced (DF) zinc oxide (ZnO) nanoflowers (NFs) for flexible gas sensors have been successfully fabricated on a polyimide (PI) substrate with single-walled carbon nanotubes (SWCNTs) as electrode. The fabricated sensor comprises ZnO nanoshells laid out on a PI substrate at regular intervals, on which ZnO nanorods (NRs) were grown in- and outside the shells to maximize the surface area and form a connected network. This three-dimensional network structure possesses multiple gas diffusion channels and the micropatterned island structure allows the stability of the flexible devices to be enhanced by dispersing the strain into the empty spaces of the substrate. Moreover, the micropatterning technique on a flexible substrate enables highly integrated nanodevices to be fabricated. The SWCNTs were chosen as the electrode for their flexibility and the Schottky barrier they form with ZnO, improving the sensing performance. The devices exhibited high selectivity toward NO2 as well as outstanding sensing characteristics with a stable response of 218.1, fast rising and decay times of 25.0 and 14.1 s, respectively, and percent recovery greater than 98% upon NO2 exposure. The superior sensing properties arose from a combination of high surface area, numerous active junction points, donor point defects in the ZnO NRs, and the use of the SWCNT electrode. Furthermore, the DF-ZnO NF gas sensor showed sustainable mechanical stability. Despite the physical degradation observed, the devices still demonstrated outstanding sensing characteristics after 10 000 bending cycles at a curvature radius of 5 mm.
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Affiliation(s)
- Jong-Woo Kim
- Department of Materials Science and Engineering and ‡School of Electrical and Electronic Engineering, Yonsei University , 50 Yonsei-ro, Soedaemun-gu, Seoul 03722, Republic of Korea
| | - Yoann Porte
- Department of Materials Science and Engineering and ‡School of Electrical and Electronic Engineering, Yonsei University , 50 Yonsei-ro, Soedaemun-gu, Seoul 03722, Republic of Korea
| | - Kyung Yong Ko
- Department of Materials Science and Engineering and ‡School of Electrical and Electronic Engineering, Yonsei University , 50 Yonsei-ro, Soedaemun-gu, Seoul 03722, Republic of Korea
| | - Hyungjun Kim
- Department of Materials Science and Engineering and ‡School of Electrical and Electronic Engineering, Yonsei University , 50 Yonsei-ro, Soedaemun-gu, Seoul 03722, Republic of Korea
| | - Jae-Min Myoung
- Department of Materials Science and Engineering and ‡School of Electrical and Electronic Engineering, Yonsei University , 50 Yonsei-ro, Soedaemun-gu, Seoul 03722, Republic of Korea
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