- 标题
- 摘要
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- 实验方案
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Tunable p- and n-type Nb:TiO<sub>2</sub> and performance optimizing of self-powered Nb:TiO<sub>2</sub>/CdS photodetectors
摘要： For the first time, Niobium-doped titanium dioxide (Nb:TiO2, NTO) and cadmium sulfide (CdS) are selected for building self-powered photodetectors for optimizing the performance. The p- or n-type NTO and the band structures of the heterojunctions can be controlled by doping Nb and tuning the sputtering power. A low sputtering power tends to produce pure anatase crystals and a high power induces additional rutile phase aligned in the (200) orientation. NTO films deposited at a sputtering power of 120 W show p-type behavior attributed to the compensation of oxygen vacancies. NTO films deposited at 180 W contain mixed anatase and rutile phases with lattice imperfections and show n-type semiconductor property after annealing. By measuring the energy band structure of n-n-type anatase-TiO2/CdS, p-n-type anatase-NTO/CdS, and n-n-type mix-NTO/CdS heterojunctions, we identify the interface carrier motion characteristics and tune the energy band structure to optimize the performance of the photodetectors. Without any external power supply, the responsivities reaches at least 0.125A/W in the mix-NTO/CdS (light source: 550 nm) and the response speed is lower than 10ms, which can be used for building a self-powered photodetector.
关键词： TiO2,self-powered,photodetector
更新于2025-09-19 17:13:59
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Giant detectivity of ZnO-based self-powered UV photodetector by inserting an engineered back gold layer using RF sputtering
摘要： The realization of high-responsivity, self-powered and low-cost ultraviolet (UV) photodetector (PD) based on eco-friendly and earth-abundant compounds, remains far from satisfactory for future optoelectronic applications. In this paper, we demonstrated a new high-performance UV-PD based on planar ZnO thin-film, efficiently operating without any power supply. The proposed device was elaborated by evaporating an engineered back metallic layer onto the glass substrate and then depositing ZnO thin layer through RF sputtering technique. The sensor structural and optical properties were systematically analyzed by the techniques of X-ray diffraction (XRD) and UV–Vis absorbance spectrometry. The resulted ZnO UV-PD showcased a clear and distinctive photovoltaic behavior. Interestingly, it also demonstrated a high responsivity of 0.38A/W and a giant detectivity exceeding 1014 Jones at zero bias, which is much higher than other reported self-powered UV-PD despite the use of an All-ZnO structure. The device photodetecting mechanism in self-driven mode was discussed using the energy band diagram, where the key role of the engineered back metallic layer in modulating the electric field distribution within the ZnO active region to effectively achieve an asymmetric behavior is emphasized. Therefore, the presented work offers a novel pathway to design high-responsivity self-powered UV-PDs based on a simple All-ZnO structure.
关键词： detectivity,ZnO,Self-powered,low cost,UV photodetectors,RF sputtering
更新于2025-09-16 10:30:52
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MgO/ZnO microsphere bilayer structure towards enhancing the stability of the self-powered MAPbI3 perovskite photodetectors with high detectivity
摘要： In recent years, organic-inorganic hybrid perovskite photodetectors (PDs) have been regarded as promising next-generation PDs. However, the commercialization of the perovskite PDs still faces signi?cant challenges, one of which is the poor stability. Herein, we demonstrate MgO/ZnO microsphere (MS) bilayer structure for improving the device stability with high detectivity. In this MgO/ZnO MS bilayer, ZnO MS array sca?old can facilitate the penetration of perovskite into nano-arrays and bene?ts the light harvest e?ciency due to the special micro-sphere array structure, which behaves a big gap between aligned nanostructures. MgO passivates the interface between ZnO and perovskite, enhancing the device stability and promoting the carrier transport. Finally, our PDs with the bilayer structure exhibit high performance with the on/o? ratio of up to more than 7.0 × 104, the linear dynamic range of 87.7 dB, and the detectivity of 1.5 × 1012 Jones, all of which are better than those of the device without MgO. More importantly, the device with the bilayer structure shows better stability compared with the device without MgO. Under illumination with the optical power of 314 mW/cm2, the photocurrent of the device with MgO shows almost no attenuation after continuous illumination for 30 min. In addition, after storing in air for 15 days, the performance of the device with MgO exhibits slight attenuation and the on/o? ratio is still as high as 2.3 × 104, indicating that the device has good storage stability.
关键词： MgO passivation,Perovskite photodetector,Self-powered,ZnO microsphere
更新于2025-09-16 10:30:52
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A wearable helical organic–inorganic photodetector with thermoelectric generators as the power source
摘要： A self-powering feature is particularly appealing for wearable electronic devices when facing the challenges of energy and environmental crises. Photodetectors (PDs), as promising candidates for health and environment monitoring, are urgently desired to meet the requirements of being wearable and powerless. Unlike conventional photovoltaic-type PDs, we have come up with a novel approach to make a self-powered wearable PD, which involves connecting PDs with thermoelectric generators (TEGs) in series on the surface of a three-dimensional helical polymer substrate. The wearable system is light-weight, flexible and breathable. More importantly, compared with photovoltaic-type self-powered PDs, wearable PDs powered by TEGs will work as a system whose output signal can be greatly amplified by the temperature difference between the human body and the environment in winter when UV intensity is relatively low.
关键词： UV intensity,thermoelectric generators,self-powered,wearable electronic devices,photodetectors
更新于2025-09-16 10:30:52
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Enhanced photoresponse in ZnO nanorod array/p-GaN self-powered ultraviolet photodetectors via coupling with CuO nanostructures
摘要： ZnO nanorod arrays (ZnO NRAs) coupled with coral-like CuO nanostructures (CuO CLNs) were prepared by low-temperature hydrothermal method. Self-powered ultraviolet (UV) photodetectors (PDs) based on ZnO NRAs/CuO CLNs/p-GaN heterostructure were fabricated via a direct-contact method. Under UV illumination (1.46 mW cm?2), the ratios of photocurrent to dark current (Iphoto/Idark), photo-responsivity and speci?c detectivity for the ZnO NRAs/CuO CLNs/p-GaN heterojunction self-powered PD were estimated to be 1143, 1.44 mA W?1 and 5.9×1010 cm Hz1/2/W at 0 V, which were about ～187, ～104 and ～153 times greater than those of the ZnO NRAs/p-GaN self-powered PD, respectively. Moreover, the PD displayed faster response time, excellent stability and repeatability by coupling with CuO CLNs. The mechanism of the enhanced photoresponse performance was discussed through the energy band diagram.
关键词： self-powered,CuO nanostructures,ultraviolet photodetector,ZnO nanorods
更新于2025-09-16 10:30:52
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Analysis of Photovoltaic String Failure and Health Monitoring with Module Fault Identification
摘要： In this paper, photovoltaic (PV) string failure analysis and health monitoring of PV modules based on a low-cost self-powered wireless sensor network (WSN) are presented. Simple and effective fault detection and diagnosis method based on the real-time operating voltage of PV modules is proposed. The proposed method is verified using the developed health monitoring system which is installed in a grid-connected PV system. Each of the PV modules is monitored via WSN to detect any individual faulty module. The analysis of PV string failure includes several electrical fault scenarios and their impact on the PV string characteristics. The results show that a degraded or faulty module exhibits low operating voltage as compared to the normal module. The developed health monitoring system also includes a graphical user interface (GUI) program which graphically displays the real-time operating voltage of each module with colors and thus helping users to identify the faulty modules easily. The faulty modules identification approach is further validated using the PV module electroluminescence (EL) imaging system.
关键词： photovoltaic module fault detection,health monitoring,Internet of Things,photovoltaic string,graphical user interface,self-powered wireless sensor network
更新于2025-09-16 10:30:52
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - A High-Performance Self-Powered UV Photodetector Based on Self-Doping TIO <sub/>2</sub> Nanotube Arrays
摘要： In this paper, we present a high-performance self-powered ultraviolet (UV) photodetector using electrochemical micro-porous-channel arrays based on a cost-effective and environment-friendly black TiO2 nanotube arrays (BTNAs) and polysulfide (S2-/Sx2-) electrolyte. By self-doping TiO2 the concentration and lifetime of UV photo-generated carriers are increased due to increasing oxygen vacancies and Ti3+ defects in BTNAs, effectively enhancing the carrier transport and multiple exciton effect of carriers, and thus the self-powered UV photodetector based on electrochemical micro-porous-channel arrays demonstrates a high photoresponsivity of ~22 mA/W and high-speed photoresponse of ~4 ms in rise and decay time.
关键词： TiO2 nanotube arrays,self-powered sensors,electrochemical sensors,ultraviolet photodetector
更新于2025-09-16 10:30:52
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Highly sensitive, ultra-low dark current, self-powered solar-blind ultraviolet photodetector based on ZnO thin-film with an engineered rear metallic layer
摘要： In this paper, novel self-powered, solar-blind UV photodetector (PD) designs based on a ZnO thin-film with engineered back metal layer (BML) were fabricated by RF magnetron sputtering and e-beam evaporation techniques. An exhaustive study concerning the impact of dissimilar BML (Au and Ni) on the device structural, optical and electrical properties was carried out. The measured I–V curves illustrated an asymmetrical behavior, enabling a clear and distinctive photovoltaic mode. Superb sensitivity of 107, high ION/IOFF ratio of 149dB, ultralow dark-noise current less than 11pA and responsivity exceeding 0.27A/W were reached for the prepared ZnO-based UV-PDs in self-powered mode. The role of the engineered BML in promoting effective separation and transfer of the photo-induced carriers was discussed using the band-diagram theory. The influence of the annealing process on the UV-sensor performance was also investigated. The annealed device at 500°C demonstrated a lower dark current of a few picoamperes and a high rejection ratio of 2.2×103, emphasizing its exciting visible blindness characteristics. Therefore, the use of an engineered BML with optimized annealing conditions open up new perspectives to realizing high-performance, self-powered solar-blind UV-PDs based on simple thin-film-ZnO structure strongly desirable for various optoelectronic applications.
关键词： Self-powered,ZnO,Annealing,Solar-blind,UV photodetectors,RF sputtering
更新于2025-09-16 10:30:52
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Quantum Transmission Line Modelling and Experimental Investigation of the Output Characteristics of a Terahertz Quantum Cascade Laser
摘要： Magnetorheological (MR) fluid is a widely used smart material due to its outstanding properties. This paper presents the design, development, modeling, and prototype testing of a self-energizing and self-powered MR brake-by-wire system, whose aforementioned capabilities are enabled by brake energy harvesting. The system is composed mainly of a typical T-shaped drum-type MR brake and a wedge mechanism for self-energizing purpose. Into the system, we also install a generator that harvests regenerative energy during braking, thereby creating a self-power capability that cannot be found in common vehicular brake-by-wire systems. Brake torque analysis is conducted, and the braking process is simulated in a MATLAB/Simulink environment. Finite element analysis of the magnetic field, temperature field, and mechanical strength of critical components is carried out. The simulation results are used to optimize design parameters and material selection. Finally, prototypes and a corresponding test rig are established. The experimental results show that only about 30 W of power is required to generate a 315 N·m brake torque and that the regenerative power produced by the generator can be used for braking, thus fulfilling the self-power requirement. The investigation of different wedge angles indicates that considerable self-energizing occurs under a small wedge angle. The findings demonstrate that the brake actuator, which has a relatively small volume, can significantly enlarge brake torque while harvesting brake energy. This feature enables the promising application of MR fluids in automotive brake systems.
关键词： wedge mechanism,energy harvesting,magnetorheological (MR),Brake-by-wire system,self-powered capability
更新于2025-09-16 10:30:52
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Self-powered perovskite/CdS heterostructure photodetectors
摘要： Methylammonium lead halide perovskites have gained a lot of attention because of their remarkable physical properties and potential for numerous (opto)electronic applications. Here, high-performance photodetectors based on CH3NH3PbI3 (MAPbI3)/CdS heterostructures, are demonstrated. The resulting self-powered MAPbI3/CdS photodetectors show excellent operating characteristics including a maximum detectivity of 2.3×1011 Jones with responsivity of 0.43 A/W measured at 730 nm. A temporal response time of less than 14 ms was achieved. The mechanisms of charge separation and transport at the interface of the MAPbI3/CdS junction were investigated via conductive atomic force microscopy (C-AFM) and photoconductive atomic force microscopy (PC-AFM). Obtained results show that grain boundaries exhibit higher photocurrent than flat regions of the top perovskite layer, which indicates that excitons preferentially separate at the grain boundaries of the perovskite thin film, i.e. at the edges of the MAPbI3 crystals. The study of the photoelectric mechanism at the nanoscale suggests the device performance could potentially be fine-tuned through grain boundary engineering, which provides essential insights for the fabrication of high-performance photodetector. The demonstrated self-powered photodetector is promising for numerous applications in low-energy consumption optoelectronic devices.
关键词： perovskite,photodetector,heterojunction,photovoltaic,self-powered photodetectors,photoconductive atomic force microscopy
更新于2025-09-16 10:30:52