- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Afterglow Effects as a Tool to Screen Emissive Non-Geminate Charge Recombination Processes in Organic Photovoltaic Composites
摘要： Disentangling temporally-overlapping charge carrier recombination events in organic bulk heterojunctions by optical spectroscopy is challenging. Here, a new methodology for employing delayed luminescence spectroscopy is presented. The proposed method is capable of distinguishing between recombination of spatially-separated charge carriers and trap-assisted charge recombination simply by monitoring the delayed luminescence (afterglow) of bulk heterojunctions with a quasi time-integrated detection scheme. Applied on the model composite of the donor poly(6,12-dihydro-6,6,12,12-tetraoctyl-indeno[1,2-b]fluorene-alt-benzothiadiazole) (PIF8BT) polymer and the acceptor ethyl-propyl perylene diimide (PDI) derivative, i.e. PIF8BT:PDI, the luminescence of charge-transfer (CT) states created by non-geminate charge recombination on the ns – μs time scale is observed. Fluence-dependent, quasi time-integrated detection of the CT luminescence monitors exclusively emissive charge recombination events, while rejecting the contribution of other early-time emissive processes. Trap-assisted and bimolecular charge recombination channels are identified based on their distinct dependence on fluence. The importance of the two recombination channels is correlated with the layer’s order and electrical properties of the corresponding devices. Four different microstructures of the PIF8BT:PDI composite obtained by thermal annealing are investigated. Thermal annealing of PIF8BT:PDI shrinks the PDI domains in parallel with the growth of the PIF8BT domains in the blend. Common to all states studied, the delayed CT luminescence signal is dominated by trap-assisted recombination. Yet, the minor fraction of fully-separated charge recombination in the overall CT emission increases as the difference in the size of the donor and acceptor domains in the PIF8BT:PDI blend becomes larger. Electric field-induced quenching measurements on complete PIF8BT:PDI devices confirm quantitatively the dominance of emissive trap-limited charge recombination and demonstrate that only 40% of the PIF8BT/PDI CT luminescence comes from the recombination of fully-separated charges, taking place within 200 ns after photoexcitation. The method is applicable to other non-fullerene acceptor blends beyond the system discussed here, if their CT state luminescence can be monitored.
关键词： multiple-diode equivalent circuit,fill factor,solar cell,charge trapping,perylene diimides,non-fullerene acceptors,delayed luminescence,photodetector
更新于2025-09-12 10:27:22
-
Silicon photodetector for integrated lithium niobate photonics
摘要： We demonstrate the integration of an amorphous silicon photodetector with a thin film lithium niobate photonic platform operating in the visible wavelength range. We present the details of the design, fabrication, integration, and experimental characterization of this metal-semiconductor-metal photodetector that features a responsivity of 22 mA/W to 37 mA/W over the wide optical bandwidth spanning in the 635 nm–850 nm wavelength range.
关键词： lithium niobate,visible wavelength range,integration,photonics,silicon photodetector
更新于2025-09-12 10:27:22
-
UV-blue photodetectors based on n-SnOx/p-diamond
摘要： High-performance self-powered UV-blue photodetector was fabricated based on n-SnOx/p-diamond heterojunction. The SnOx film was deposited on the high temperature and high pressure synthetic boron doped diamond wafer by RF magnetron sputtering. This heterojunction device exhibits a good rectification behavior with a rectification ratio of 3.15×104 at ± 3 V. At zero bias, the device responds in the wavelength ranging from 250nm to 500nm with a peak response at 350nm. The photoresponse rise time and decay time of the device are both less than 2 s under UV-blue illumination with different wavelengths. These results demonstrate that the n-SnOx/p-diamond heterojunction device has potential applications in the field of UV-blue detection.
关键词： Photodetector,RF sputtering,Self-powered,Thin films,Heterojunction,XPS
更新于2025-09-12 10:27:22
-
High-Performance Photodetector Based on Graphene Quantum Dot/CH3NH3PbI3 Perovskite Hybrid
摘要： Organometallic perovskites have great potential for their utilization in photodetector. However, the photoresponsivity of the perovskite film is limited by the low light absorption and charge transport capability. The preparation of good quality film with higher light–harvesting capability on the substrate has been a challenging job till now. In this work, we have developed high–quality white fluorescence graphene quantum dots and CH3NH3PbI3 hybrid film by one–step solvent–induced fast deposition–crystallization technique for the photodetector applications. Various amount of graphene quantum dots is added in composites to optimize the device performance and the hybrid film results in smooth and compactly distributed crystalline grains. The hybrid film device has exhibited 2 times higher photocurrent–to–dark current ratio, three–fold improved responsivity of 12 A W-1, detectivity enhancement upto 6.5 × 1011 Jones and a faster response speed compare to that of the neat MAPbI3 at -3 V bias voltage. The graphene quantum dots addition induces efficient charge transfer and enhances the photocurrent by more than 2 times compare to the neat film. High light absorption and fast charge transport capability of the film are the primary responsible for the high performance of the photodetector.
关键词： Photodetector,Graphene quantum dot,High–quality film,Fast deposition crystallization,CH3NH3PbI3 perovskite
更新于2025-09-12 10:27:22
-
Nanoplasmonic 1D Diamond UV Photodetectors with High Performance
摘要： Diamond nanowires have recently drawn substantial attention due to their unique physical and chemical properties for electrochemical sensors, optoelectronics, and nanophotonics applications. However, diamond nanowire based ultraviolet photodetectors have not been reported because of the challenges involved in synthesizing crystalline diamond nanowires with controllable morphologies and, more fundamentally, the material’s high carrier concentration with low mobilities that limits the obtainable photoresponsivity. The synergetic integration of ultrananocrystalline diamond (UNCD) nanowires with nanoplasmonic enhancement by noble metal nanoparticles is a very promising approach to overcome these shortcomings. Here we report the fabrication of boron doped ultrananocrystalline diamond nanowires functionalized with the platinum nanoparticles to form self-powered ultraviolet photodetectors that exhibit an ultrahigh photoresponsivity of 388 Amp/Watt at 300 nm wavelength, a fast response time around 20 ms, and a good UV/visible rejection ratio of about five orders of magnitude under zero-bias condition.
关键词： ultraviolet photodetector,nanowire,metal nanoparticle,ultrananocrystalline diamond,nanoplasmonics
更新于2025-09-12 10:27:22
-
High signal-to-noise ratio for high-impedance-loaded nano-photodetector toward attojoule optical reception
摘要： We demonstrate a high signal-to-noise ratio (SNR) for a photonic-crystal nanophotodetector (PD). The ultralow-capacitance nano-PD can be terminated with a load resistor with a resistance as high as 59 kX for ef?cient light-to-voltage conversion, and its strong thermal-noise suppression leads to an SNR that is 30 dB higher than that of the conventional p-i-n PD terminated with a 50-X load. The noise equivalent power is only 500 fW/(cid:2)Hz, while a gigahertz-level bandwidth can be maintained when considering that the PD capacitance is only 1 fF. Theoretically, this allows optical reception at less than 100 aJ to obtain a bit error rate of 10–9. The resistor-loaded nano-PD requires a small electrical biasing energy comparable to the optical energy, which is remarkably energy saving compared with avalanche PDs or other PDs integrated with ampli?ers. Such a receiver promises a dense optical interface with CMOS electronics in photonic networking and processing chips.
关键词： high signal-to-noise ratio,attojoule optical reception,thermal-noise suppression,nano-photodetector,photonic-crystal
更新于2025-09-12 10:27:22
-
Three-dimensional ZnO nanorods growth on ZnO nanorods seed layer for high responsivity UV photodetector
摘要： Three-dimensional ZnO nanorods (NRs) were synthesized by hydrothermal method on ZnO seed layer including horizontal ZnO NRs. The ZnO seed layers consist of different values of NRs were synthesized by spin-coating. The different seed layers and ZnO nanorods arrays were characterized using field emission scanning electron microscopy, X-ray diffraction. Horizontally dispersed NRs on the substrate formed an overlapping junction structure into seed layer as ZnO NRs network. NRs grown on the seed layer including horizontal NRs were oriented in different directions to form three-dimensional ZnO NRs in flower shape. The electrical resistance of sensors based NRs array decreased dramatically with increasing NRs added to ZnO seed layer. Results show that ultraviolet photocurrent increased from 1.7 to 23 μA which is suitable for fabrication of practical photodevices.
关键词： UV photodetector,ZnO nanorods,seed layer,photocurrent,hydrothermal method
更新于2025-09-12 10:27:22
-
Simulations of Nanoscale Room-Temperature Waveguide-Coupled Single-Photon Avalanche Detectors for Silicon-Photonic Sensing and Quantum Applications
摘要： Photonic qubits can represent an ideal choice in quantum-information science since photons travel at the speed of light and interact weakly with the environment over long distances. In this context, technological platforms allowing the development and implementation of chip-scale integrated-photonics represent a possible solution towards scalable quantum networking schemes. However, at present, most examples of integrated quantum photonics still require the coupling of light to external photodetectors operating at very low temperatures. In this paper, we demonstrate that the GeSn/Si-in-SOI technological platform can be a good candidate to realize integrated single-photon avalanche detectors (SPADs), operating at room temperature. Thus, we report the design and simulation of waveguide-based SPADs for operation at 1550 nm and 2000 nm wavelengths. We calculate the breakdown voltage, the dark count rate (DCR), the single photon detection efficiency (SPDE), the noise equivalent power (NEP), the dark count and the afterpulsing probabilities by simulating the avalanche process and the statistical features in a self-consistent way. The PIPIN SPAD performance parameters are estimated as a function of the GeSn’s threading dislocation density and of the temperature. We also demonstrate that for operation at 1550 nm and 2000 nm wavelengths with the 220-nm GeSn separate-absorber film centered in the 250-nm-high Si waveguide end, it is possible cover a number of applications at room or near room temperature, ranging from ultra-sensitive LIDAR to quantum communications, metrology, sensing and key distribution.
关键词： Optoelectronic and Photonic device,Photonic integrated circuits,Silicon Photonics,Photodetector,Avalanche photodiode
更新于2025-09-12 10:27:22
-
Controlled Plasma Thinning of Bulk MoS <sub/>2</sub> Flakes for Photodetector Fabrication
摘要： The electronic properties of layered materials are directly determined based on their thicknesses. Remarkable progress has been carried out on synthesis of wafer-scale atomically molybdenum disulfide (MoS2) layers as a two-dimensional material in the past few years in order to transform them into commercial products. Although chemical/mechanical exfoliation techniques are used to obtain a high-quality monolayer of MoS2, the lack of suitable control in the thickness and the lateral size of the flakes restrict their benefits. As a result, a straightforward, effective, and reliable approach is widely demanded to achieve a flake with control in its thickness for optoelectronic applications. In this study, thick MoS2 flakes are obtained by a short-time bath sonication in dimethylformamide solvent, which are thinned with the aid of a sequential plasma etching process using H2, O2, and SF6 plasma. A comprehensive study has been carried out on MoS2 flakes based on scanning electron microscopy, atomic force microscopy, Raman, transmission electron microscopy, and X-ray photoelectron microscopy measurements, which ultimately leads to a two-cycle plasma thinning method. In this approach, H2 is used in the passivation step in the first subcycle, and O2/SF6 plasma acts as an etching step for removing the MoS2 layers in the second subcycle. Finally, we show that this technique can be enthusiastically used to fabricate MoS2-based photodetectors with a considerable photoresponsivity of 1.39 A/W and a response time of 0.45 s under laser excitation of 532 nm.
关键词： photodetector,MoS2,optoelectronic applications,plasma thinning,two-dimensional materials
更新于2025-09-12 10:27:22
-
High performance graphene-like thinly layered graphite based visible light photodetector
摘要： In this work, the drop casting method is utilized to obtain a thin graphene-like graphite layer as a photodetection layer on a SiO2/Si substrate, and its performance is characterized to determine its potential use in commercial applications. The thin layer is formed by first synthesizing graphite soot from a butane flame before being turned into a liquid solution and drop-casted onto the substrate to form a thin graphene-like graphite film. Field emission scanning electron microscope and Raman vibrational mode analyses indicate that the fabricated graphene-like graphite layer has characteristics similar to the graphene. The graphene-like graphite photodetector demonstrates a narrow photoresponse from 530 to 680 nm, covering visible sources from green to red. The responsivity and external quantum efficiency of the device under the illumination of red laser 660 nm is found to be around 148 mA W?1 and 27.8% respectively and is faster than that reported for similar systems using graphene and reduced graphene oxide previously. A fast response time of 83.7 and 28 μs at a modulation frequency of 1.0 and 10000 Hz respectively from the graphene-like thinly layered graphite photodetector shows potential application for the development of low-cost carbon-based photodetectors in near future.
关键词： Responsivity,Butane flame,Graphite,Frequency modulation,Photodetector
更新于2025-09-12 10:27:22