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Organic Multi-Channel Optoelectronic Sensors for Wearable Health Monitoring
摘要： Recent progress in printed optoelectronics and their integration in wearable sensors have created new avenues for research in reflectance photoplethysmography (PPG) and oximetry. The reflection-mode sensor, which consists of light emitters and detectors, is a vital component of reflectance oximeters. Here, we report a systematic study of the reflectance oximeter sensor design in terms of component geometry, light emitter and detector spacing, and the use of an optical barrier between the emitter and the detector to maximize sensor performance. Printed red and near-infrared (NIR) organic light-emitting diodes (OLEDs) and organic photodiodes (OPDs) are used to design three sensor geometries: (1) Rectangular geometry, where square OLEDs are placed at each side of the OPD; (2) Bracket geometry, where the OLEDs are shaped as brackets and placed around the square OPD; (3) Circular geometry, where the OLEDs are shaped as block arcs and placed around the circular OPD. Utilizing the bracket geometry, we observe 39.7% and 18.2% improvement in PPG signal magnitude in the red and NIR channels compared to the rectangular geometry, respectively. Using the circular geometry, we observe 48.6% and 9.2% improvements in the red and NIR channels compared to the rectangular geometry. Furthermore, a wearable two-channel PPG sensor is utilized to add redundancy to the measurement. Finally, inverse-variance weighting and template matching algorithms are implemented to improve the detection of heart rate from the multi-channel PPG signals.
关键词： flexible electronics,printed electronics,pulse oximetry,organic optoelectronics,Reflection photoplethysmography sensor,wearable sensors
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || Simultaneous Nanoplasmonic Sensing and Transmission Electron Microscopy Characterization
摘要： The research focuses on the development of a novel optoelectronic device for sensing applications, utilizing advanced materials and fabrication techniques to achieve high sensitivity and specificity. The study demonstrates the device's potential in real-world applications through a series of experimental validations.
关键词： sensing,high sensitivity,advanced materials,optoelectronics,fabrication techniques
更新于2025-09-11 14:15:04
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Dipolar and Quadrupolar Luminophores Based on 1,8‐Dimethylcarbazole?Triazine Conjugates for High‐Efficiency Blue Thermally Activated Delayed Fluorescence OLEDs
摘要： Highly efficient blue thermally activated delayed fluorescence emitters combining 1,8-dimethylcarbazoles as a donor (D) unit with a triazine acceptor (A) core are designed and synthesized. A D-A-D-type emitter exhibits superior photo- and electroluminescence (EL) properties compared to a D-A-type counterpart and displays a brilliant blue EL emission with a maximum external EL quantum efficiency as high as 21.2 %.
关键词： organic light-emitting diodes,optoelectronics,donor-acceptor systems,electroluminescence,delayed fluorescence
更新于2025-09-11 14:15:04
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Organic and hybrid organic-inorganic flexible optoelectronics: Recent advances and perspectives
摘要： Extensive research in flexible optoelectronics, based on organic and organic-inorganic materials, has proven a leading topic because of their superior advantages in solution process-ability, large-area and cost-efficient fabrication. What matters most in the fabrication quality of optoelectronic devices are the materials, optimization of device structures, and manufacturing processe. The materials exhibit great merits, such as power conversion efficiencies (PCEs) for photovoltaic technology or charge mobilities for field effect transistors. Herein, we summarized the recent literature pertaining to materials in the application area of large-scale roll-to-roll (R2R) processable, 3D printed flexible electronics and optoelectronics.
关键词： Large area,Flexible optoelectronics,3D printed,Solution process-ability,Roll-to-roll
更新于2025-09-11 14:15:04
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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - An Antenna-integrated UTC-PD based Photonic Emitter Array
摘要： In this paper we present a photonics-based wideband emitter module, using two uni-travelling carrier photodiodes coupled to a pair of high gain planar antennas, reporting a two-element array operating in the 50 to 120 GHz frequency range. This antenna array provides a maximum gain of 15.9 dBi with side-lobes less than -15 dB. The measurements show a record 3-dB bandwidth of 45 GHz, covering three waveguide bands (V, E and F). Moreover, a combined peak radiated power of -6.4 dBm (214 (cid:2)W) at 75 GHz is also achieved. The scalable design presented allows for realization of photonic phased antenna array.
关键词： UTC-PD,radio frequency photonics,optoelectronics,antenna array
更新于2025-09-11 14:15:04
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InAs/GaAs Quantum Dot Dual-Mode Distributed Feedback Laser Towards Large Tuning Range Continuous-Wave Terahertz Application
摘要： In this paper, a laterally coupled distributed feedback (LC-DFB) laser based on modulation p-doped multiple InAs/GaAs quantum dot (QD) structures has been fabricated. The device exhibits a high side-mode suppression ratio (SMSR) of > 47 dB and a high thermal stability of dλ/dT = 0.092 nm/K under continuous-wave (CW) operation, which is mainly attributed to the high material gain prepared by modulation p-doping and rapid thermal annealing (RTA) process, and the significantly reduced waveguide losses by shallow-etched gratings and its close proximity to the laser ridge feature in the LC-DFB laser. With this superior performance of the DFB laser, the wide tunable dual-wavelength lasing operation has been obtained by delicately defining different periods for the grating structures on the two sides of the laser ridge or combining the reduced laser cavity length. The wavelength spacing between the two lasing modes can be flexibly tuned in a very wide range from 0.5 to 73.4 nm, corresponding to the frequency difference from 0.10 to 14 THz, which is the largest tuning range by the utilization of single device and hence providing a new opportunity towards the generation of CW THz radiation.
关键词： Semiconductor lasers,Lasers,Distributed feedback,Optoelectronics,Terahertz imaging,Quantum well, wire, and dot devices
更新于2025-09-11 14:15:04
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Oxidation Induced Polymerization of InP Surface and Implications for Optoelectronic Applications
摘要： InP is among the most studied materials for energy-conversion applications including optoelectronics and photoelectrochemical devices. One of the longstanding challenges with this material—and III-V semiconductors more generally—is to understand and control surface oxide formation, which critically impacts device functionality, performance and durability. We integrate advanced in situ ambient pressure X-ray photoelectron spectroscopy (APXPS) and ab initio simulations to reveal the mechanism of the oxidation process on InP(001) surface. By interpreting the APXPS results through direct ab initio spectroscopic calculations of surface models, and by comparing calculated and measured work functions, we provide an unbiased picture of the chemical evolution of the thermal oxide. At low temperatures (< 573 K), O2 exposure leads to predominant formation of crosslinked POx units dispersed with submonolayer thickness, which grow into an amorphous 2D film that is kinetically limited to the surface layer. Increased temperature (> 573 K) leads to the polymerization of POx units and the formation of a complex, inhomogeneous 3D network of surface oxide that is progressively indium rich and phosphorus poor towards the surface. Finally, accelerated phosphorus loss via a hitherto unreported coupled charge-transfer isomer transformation mechanism leads to the formation of a thick, amorphous In2O3-like oxide at 773 K with very different optoelectronic and hot carrier transportation properties. In addition to unraveling complex mechanisms of surface oxidation, our results suggest the possibility of deliberately tuning oxide composition by leveraging competition between thermodynamic and kinetic factors.
关键词： InP,APXPS,surface oxidation,ab initio simulations,photoelectrochemical devices,optoelectronics
更新于2025-09-11 14:15:04
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Self-Healing of Photocurrent Degradation in Perovskite Solar Cells: The Role of Defect-Trapped Excitons
摘要： Solution-processed lead halide perovskites have emerged as one of the most promising materials in optoelectronic applications. However, the perovskites are not stable over prolonged solar illumination. A recent experimental study has revealed light-activated photocurrent degradation and self-healing in the lead halide perovskites, which has important implications in tackling the photostability problems of the perovskites. Unfortunately, the physical origin of the experimental observations is unclear. In this work, we propose a first-principles theory which can elucidate all key experimental observations. By focusing on defect-trapped excitons, the theory can rationalize both fast and slow timescales of self-healing, contrasting dynamics of the photocurrent degradation and its recovery, and steep temperature dependence of the two competing processes. We further predict that the same phenomenon of self-healing could also be observed in other lead halide perovskites with even faster timescales of recovery. The work provides a general framework to elucidate defect-controlled excitation dynamics in perovskites.
关键词： Energy Conversion and Storage,Plasmonics and Optoelectronics
更新于2025-09-11 14:15:04
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Kinetic Monte Carlo Study of the Role of the Energetic Disorder on the Open-circuit Voltage in Polymer:Fullerene Solar Cells
摘要： One major factors limiting the e?ciency in organic solar cells (OSCs) is the low open-circuit voltage (Voc). Existing theoretical studies link the Voc with the charge transfer (CT) state and non-radiative recombination. However, also morphology and energetic disorder can have a strong impact on the Voc within realistic bulk-heterojunction OSCs. In this work, we present a kinetic Monte Carlo study on the role of the energetic disorder on the maximum Voc. We compute the quasi-Fermi level splitting for di?erent energetic disorder and analyze the impact of the energetic disorder at the donor-acceptor interface as well as correlations in the site energies on the Voc. Our results show that the interface strongly controls the maximum Voc. For a higher interface disorder, charge densities and non-geminate recombination increases, and the Voc is reduced. Furthermore, the correlated morphologies show an increase in the maximum Voc and a reduced impact of the energetic disorder.
关键词： Open-circuit Voltage,Kinetic Monte Carlo,Energy Conversion and Storage,Plasmonics and Optoelectronics,Polymer:Fullerene Solar Cells
更新于2025-09-11 14:15:04
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Handbook of Graphene || Hybrid Graphene–Silicon Photonic and Optoelectronic Integrated Devices
摘要： Graphene, a monolayer of carbon atoms arranged in a honeycomb pattern, has many intriguing optical and electrical properties, providing us numerous applications in optoelectronics, nonlinear optics, and biochemical sensing. However, due to the atomic thickness of the material, light–matter interactions in graphene are intrinsically weak, which greatly limit its practical applications. To overcome this challenge, graphene-on-silicon photonic integrated circuits (PICs) have been proposed and demonstrated in recent years. In such PICs, the propagating light in silicon waveguides can strongly interact with the top-layer graphene through in-plane evanescent–field coupling. On the other hand, with unique properties in photonics and optoelectronics, graphene is expected to open a new avenue for the development of revolutionized on-chip applications, which cannot be precedent based on traditional silicon photonic technology. Therefore, this emerging area has attracted a great deal of attention. In this Chapter, we comprehensively introduce theoretical principles, fabrication processes, and applications of graphene-on-silicon PICs, and review recent research progress in this topic.
关键词： silicon photonics,optoelectronics,photonic integrated circuits,optical interconnects,biochemical sensing,Graphene,mid-infrared photonics,nonlinear optics
更新于2025-09-11 14:15:04