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Growth of CdSe/MoS2 vertical heterostructures for fast visible-wavelength photodetectors
摘要： Heterostructures composed of different semiconducting materials have aroused wide attentions due to their fascinating properties originated from the interfaces. Particularly, the recent two dimensional layered materials (2DLM) have provided novel platforms to flexibly design the heterostructures for diverse electronic and optoelectronic applications. In this work, we have reported the growth of CdSe nanoplates/MoS2 monolayer vertical heterostructures with efficient and fast visible-wavelength photodetections. Highly dense CdSe nanoplates were vertically assembled on monolayer MoS2 through a two-step chemical vapor deposition (CVD) process. The interfacial photoinduced charge behaviors were investigated in detail via the time resolution photoluminescence (TRPL) measurements, revealing the efficient charge transfer across the heterointerface. Benefiting from the large CdSe coverage and efficient charge transfer, superior photodetection performances of the CdSe/MoS2 heterostructures can be obtained with an enhanced photoresponsivity of 1.63 A/W, which can be further improved to be 12 A/W via applying the gate voltage. Besides, the heterostructure detectors also exhibit a very fast photoresponse speed of 370 μs, much faster than previous photodetectors based on CVD-grown 2D heterostructures. The as-synthesized CdSe/MoS2 heterostructures may find important applications in integrated optoelectronic systems.
关键词： Responsivity,Chemical vapor deposition,Photodetectors,Vertical heterostructures,CdSe/MoS2
更新于2025-09-12 10:27:22
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Sponge-templated production of ultra-thin ZnO nanosheets for printed ultraviolet photodetectors
摘要： This paper describes a simple and convenient approach to synthesize large amounts of ZnO nanosheets, which are suitable for producing a key component, i.e., colloidal nanoink, of printed ultraviolet photodetectors. ZnO nanosheets are produced by atomic layer deposition, where a three-dimensional polymer sponge with a large specific surface area is used as the template. Systematic studies including scanning electron microscopy, X-ray diffraction, and transmission electron microscopy reveal that the synthesized ZnO nanosheets have a good crystalline quality and mechanical flexibility. After dispersing ZnO nanosheets in a solvent to form a stable and colloidal nanoink, an ultraviolet photodetector is demonstrated through the printing method. Such a printed ultraviolet photodetector that utilizes ZnO nanosheets as the functional materials exhibits a high responsivity of (cid:2)148 A/W and a response time of 19 s. Our present study may provide a practical method to produce large amounts of functional nanosheets for printing electronics, which paves the way for developing high-performance, low-cost, large-area printed, and flexible electronics.
关键词： atomic layer deposition,printing electronics,ultraviolet photodetectors,ZnO nanosheets
更新于2025-09-12 10:27:22
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Graphene Quantum Dots Promoted the Synthesis of Heavily n-Type Graphene for Near-Infrared Photodetectors
摘要： The application of graphene in the field of microelectronics is becoming more and more urgent with the emergence of bottlenecks in semi-technical development, in which controllable graphene doping technology, therefore, strongly demanded to tune the electronic or optoelectronic properties for the fabrication of high-performance devices. We herein report a simple and convenient approach to synthesize heavily nitrogen (N) and phosphorus (P) co-doped graphene (n-type graphene) by chemical vapor deposition (CVD), which is realized by utilizing N and P co-doped graphene quantum dots (n-type GQDs) as a nucleation centers, methane (CH4) as the gaseous carbon reservoir, and copper (Cu) foils as the catalyst substrate. By the monitoring of the growth mechanism of the graphene, and an investigation revealed that co-doped GQDs could serve as the nucleation sites for producing doped-graphene films through two-dimensional epitaxial growth. Finally, the photodetector built on the heavily n-type graphene film is confirmed to perform satisfactorily, accompanying high detectivity (~1.3×1010 cmHz1/2W-1) and responsivity (58 mAW-1), at a wavelength of 1550 nm. A simple and environmentally friendly graphene doping technology has been developed, which promotes the application of doped graphene in the field of microelectronics.
关键词： quantum dots,photodetectors,chemical vapor deposition,n-type doping,graphene
更新于2025-09-12 10:27:22
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A High‐Performance Solution‐Processed Organic Photodetector for Near‐Infrared Sensing
摘要： Sensitive detection of near-infrared (NIR) light enables many important applications in both research and industry. Current organic photodetectors suffer from low NIR sensitivity typically due to early absorption cutoff, low responsivity, and/or large dark/noise current under bias. Herein, organic photodetectors based on a novel ultranarrow-bandgap nonfullerene acceptor, CO1-4Cl, are presented, showcasing a remarkable responsivity over 0.5 A W?1 in the NIR spectral region (920–960 nm), which is the highest among organic photodiodes. By effectively delaying the onset of the space charge limited current and suppressing the shunt leakage current, the optimized devices show a large specific detectivity around 1012 Jones for NIR spectral region up to 1010 nm, close to that of a commercial Si photodiode. The presented photodetectors can also be integrated in photoplethysmography for real-time heart-rate monitoring, suggesting its potential for practical applications.
关键词： high responsivity,bulk heterojunctions,photodetectors,organic photodiodes,near-infrared
更新于2025-09-12 10:27:22
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Novel approach to passivation of InAs/GaSb type II superlattice photodetectors
摘要： The innovative two-step passivation by octadecanethiol (ODT) self-assembled monolayers (SAMs) and the following silicon dioxide (SiO2) deposition was used for the type-II InAs/GaSb superlattice photodetector. To understand the mechanism of passivation, the (100) GaSb surface covered with the ODT and, for comparison, with the biphenyl thiol (BPT), was characterized by the atomic force microscopy, Raman spectroscopy and contact angle analysis. The results of the study indicated the presence of the homogeneous both the ODT and the BPT monolayers; however, the ODT SAMs were more stable. Therefore, the ODT-based wet treatment was used in the two-step passivation resulting in a reduction of the dark current by one order of magnitude for passivated detector compared with an unpassivated device.
关键词： ODT,SiO2,InAs/GaSb superlattice,BPT,photodetectors,passivation
更新于2025-09-12 10:27:22
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All-solution-processed UV-IR broadband trilayer photodetectors with CsPbBr3 colloidal nanocrystals as carriers-extracting layer
摘要： Colloidal quantum dots (CQDs) are very promising nanomaterials for optoelectronics due to their tunable bandgap and quantum confinement effect. Especially, all-inorganic CsPbX3 (X=Br, Cl and I) perovskite nanocrystals (NCs) have attracted enormous interests owing to their promising and exciting applications in photovoltaic devices. In this paper, all-solution-processed broadband photodetectors ITO/ZnO/CsPbBr3/PbS/Au with high-performance were presented. The role of CsPbBr3 QDs layer as the carriers-extracting layer in the trilayer devices was discussed. As compared with bilayer device ITO/ZnO/PbS/Au, both the dark currents and photocurrents under illumination from UV-IR broadband trilayer photodetector ITO/ZnO(80nm)/PbS(150nm)/CsPbBr3(50nm)/Au are enhanced, but the trilayer photodetector ITO/ZnO(80nm)/CsPbBr3(50nm)/PbS(150nm)/Au showed a maximum specific detectivity (D*) of 1.73×1012 Jones with a responsivity (R) of 5.31 A/W under 6.8 mW/cm2 405 nm illumination. However, another trilayer photodetector ITO/ZnO(80nm)/PbS(150nm)/CsPbBr3(50nm)/Au showed a maximum D* of 8.3×1012 Jones with a R of 35 A/W under 1.6 mW/cm2 980 nm illumination. Further, the underlying mechanism for the enhanced performance of trilayer photodetectors was discussed. Thus, this strategy of all-solution-processed heterojunction configuration paves a facile way for broadband photodetectors with high-performance.
关键词： broadband photodetectors,all-solution-processed heterojunction,Colloidal quantum dots (CQDs),CsPbBr3 perovskite nanocrystals,carrier-extraction layer
更新于2025-09-12 10:27:22
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Stable Colloidal Quantum Dot Inks Enable Inkjet-Printed High-Sensitivity Infrared Photodetectors
摘要： Colloidal Quantum Dots (CQDs) have recently gained attention as materials for manufacturing optoelectronic devices in view of their tunable light absorption and emission properties and compatibility with low-temperature thin-film manufacture. The realization of CQD inkjet-printed infrared photodetectors has thus far been hindered by incompatibility between the chemical processes that produce state-of-art CQD solution-exchanged inks; and the requirements of ink formulations for inkjet materials processing. To achieve inkjet-printed CQD solids with a high degree of reproducibility, as well as with the needed morphological and optoelectronic characteristics, we sought to overcome the mismatch among these processing conditions. In this study, we design CQD inks by simultaneous evaluation of requirements regarding ink colloidal stability, jetting conditions and film morphology for different dots and solvents. The new inks remain colloidally stable, achieved through a design that suppresses the reductant properties of amines on the dots’ surface. After drop ejection from the nozzle, the quantum dot material is immobilized on the substrate surface due to the rapid evaporation of the low boiling point amine-based compound. Concurrently, the high boiling point solvent allows for the formation of a thin film of high uniformity, as is required for the fabrication of high-performance IR photodetectors. We fabricate inkjet-printed photodetectors exhibiting the highest specific detectivities reported to date (above 1012 Jones across the IR) in an inkjet-printed quantum dot film. As a patternable CMOS-compatible process, the work offers routes to integrated sensing devices and systems.
关键词： CQD,infrared,printing,ink-jet,inkjet,colloidal quantum dots,photodetectors
更新于2025-09-12 10:27:22
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Spectral responsivity and photoconductive gain in thin film black phosphorus photodetectors
摘要： We have fabricated black phosphorus photodetectors and characterized their full spectral responsivity. These devices, which are effectively in the bulk thin film limit, show broadband responsivity ranging from <400 nm to the ~3.8 μm bandgap. In the visible, an intrinsic responsivity >6 A/W can be obtained due to internal gain mechanisms. By examining the full spectral response, we identify a sharp contrast between the visible and infrared behavior. In particular, the visible responsivity shows a large photoconductive gain and gate-voltge dependence, while the infrared responsivity is nearly independent of gate voltage and incident light intensity under most conditions. This is attributed to a contribution from the surface oxide. In addition, we find that the polarization anisotropy in responsivity along armchair and zigzag directions can be as large as 103 and extends from the band edge to 500 nm. The devices were fabricated in an inert atmosphere and encapsulated by Al2O3 providing stable operation for more than 6 months.
关键词： Two-dimensional materials,Mid-infrared,Photodetectors,Black phosphorus,Photoconductive gain
更新于2025-09-12 10:27:22
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Light Detection in Open‐Circuit Voltage Mode of Organic Photodetectors
摘要： Organic photodetectors (OPDs) are promising candidates for next-generation light sensors as they combine unique material properties with high-level performance in converting photons into electrical signals. However, low-level light detection with OPD is often limited by device dark current. Here, the open-circuit voltage (Voc) regime of OPDs is shown to be efficient for detecting low light signals (<100 μW cm?2). It is established that the light-dependence of Voc exhibits two distinct regimes as function of irradiance: linear and logarithmic. Whereas the observed logarithmic regime is well understood in organic photovoltaic cells (OPVs), it is shown experimentally and theoretically that the linear regime is due to the non-infinite shunt resistance of the OPD device. Overall, OPDs composed of rubrene and fullerene show photovoltage light sensitivity across nine orders of magnitude with a detection limit as low as 400 pW cm?2. A photovoltage responsivity of 1.75 V m2 W?1 demonstrates highly efficient performance without the necessity to supress high dark current. This approach opens up new possibilities for resolving low light signals and provides simplified design rules for OPDs.
关键词： photovoltage,open-circuit voltage,organic photodetectors,shunt resistance
更新于2025-09-12 10:27:22
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Structural Engineering of Dispersed Graphene Flakes into ZnO Nanotubes on Discontinues Ultra‐Nanocrystalline Diamond Substrates for High‐Performance Photodetector with Excellent UV Light to Dark Current Ratios
摘要： In this work, ultraviolet (UV) photodetectors based on ultra-nanocrystalline diamond (UNCD) and dispersed graphene flakes (GrF) with ZnO nanotubes (ZnTs) heterostructures are investigated. Unique hybrid nanostructure of dispersed GrF into ZnTs on discontinuous UNCD substrates using scalable techniques is presented. It is revealed from microstructural analysis that the addition of GrF into highly uniform ZnTs grown on UNCD substrates results outstanding UV photodetection properties. Thus, the GrF-ZnTs/UNCD nanostructure reveals superior UV diode performance, with an ultrahigh UV switching ratio of 19 708 at 5 V, which is excellently better than those of ZnO nanostructures. It is perceived that the perfect distribution of GrF into ZnTs on UNCD substrates results in ultrafast electron–hole recombination. The distribution of GrF and UNCD interlayer enables the new energy levels on the conduction band, which reduces the barrier height to allow fast charge carrier transportation during the UV illumination. It is believed that the addition of GrFs and UNCD layer increase the UV adsorptivity and sufficient amount of conducting path within ZnTs. Therefore, the present GrF-ZnTs/UNCD photodetector can be used as an efficient UV photodetection device with high performance and opening up new opportunities for future optoelectronic devices.
关键词： discontinuous UNCD film,ZnTs-UNCD,ZnTs UV photodetectors,graphene-UNCD,dispersed graphene flakes
更新于2025-09-12 10:27:22