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A facile method for direct bonding of single-crystalline SiC to Si, SiO2, and glass using VUV irradiation
摘要： Single-crystalline silicon carbide is an attractive material for power electronics. However, it is difficult to achieve the direct bonding of SiC to conventional Si-based materials (e.g., Si, SiO2, and glass) due to the large mismatch in coefficients of thermal expansion and lattice constants. To solve the bottleneck, we present a facile direct bonding method using vacuum ultraviolet (VUV) surface irradiation for a robust combination of SiC to Si, SiO2, and glass at low temperatures (≤ 200 oC). The mechanisms behind the VUV-irradiated bonding of SiC to Si-based materials were also investigated. According to surface characterizations, VUV irradiation can lead to smooth and hydrophilic surfaces, which are beneficial for direct bonding in humid air. The tight and defect-free SiC/Si, SiC/SiO2 and SiC/glass bonding interfaces were confirmed by transmission electron microscopy. In particular, the enriched carbon transition layers were formed on the side of silicon carbide because of the oxidation and sputtering of Si atoms during VUV irradiation. This will possibly improve the bonding interfaces and contribute to the enhanced bonding strengths. Moreover, the SiC/glass bonded pair exhibited relatively high optical transparency in the UV-Vis range. Therefore, the direct bonding of single-crystalline SiC and heterostructure Si-based materials offers great potentials for high-performance power electronics, as well as micro/nanofluidic devices.
关键词： direct bonding,vacuum ultraviolet,interface,silicon carbide
更新于2025-09-23 15:21:21
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2 <i>H</i> -Naphthopyran-Based Three-State Systems: From Solution Studies to Photoresponsive Organic/Inorganic Hybrid Materials
摘要： Densely packed self-assembled monolayers with photoresponsive naphthopyrans attached to COOH headgroups on Si(111) were studied at the solid/inert-gas interface. We demonstrate that 2H-naphtho[1,2-b]pyrans are suitable three-state photochromic systems for solution and surface studies. Switching between three states on the surface was realized using UV light, thermal relaxation and visible light as trigger and release elements as analyzed by ATR-FTIR. Compared to solution studies, surface polarity and environmental effects, especially steric hindrance, contribute to state formation by stabilization of photoisomers, acceleration and deceleration of photochemical processes, and slowed down of thermal fading.
关键词： naphthopyrans,IR spectroscopy,solid-gas interface,monolayers,photochromism
更新于2025-09-23 15:21:21
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Unraveling the impact of hole transport materials on photostability of perovskite films and p-i-n solar cells
摘要： We investigated the impact of a series of hole transport layer materials (HTLs) such as PEDOT:PSS, NiOx, PTAA, and PTA on photostability of thin films and solar cells based on MAPbI3, Cs0.15FA0.85PbI3, Cs0.1MA0.15FA0.75PbI3, Cs0.1MA0.15FA0.75Pb(Br0.15I0.85)3, and Cs0.15FA0.85Pb(Br0.15I0.85)3 complex lead halides. Mixed halide perovskites showed reduced photostability in comparison with similar iodide-only compositions. In particular, we observed light-induced recrystallization of all perovskite films except MAPbI3 with the strongest effects revealed for Br-containing systems. Moreover, halide and β FAPbI3 phase segregations were also observed mostly in mixed-halide systems. Interestingly, coating perovskite films with PCBM layer spectacularly suppressed light-induced growth of crystalline domains as well as segregation of Br-rich and I-rich phases or β FAPbI3. We strongly believe that all three effects are promoted by the light-induced formation of surface defects, which are healed by adjacent PCBM coating. While comparing different hole-transport materials, we found that NiOx and PEDOT:PSS are the least suitable HTLs due to their interfacial (photo)chemical interactions with perovskite absorbers. On the contrary, polyarylamine-type HTLs PTA and PTAA form rather stable interfaces, which makes them the best candidates for durable p-i-n perovskite solar cells. Indeed, multilayered ITO/PTA(A)/MAPbI3/PCBM stacks revealed no aging effects within 1000 h of continuous light soaking and delivered stable and high power conversion efficiencies in solar cells. The obtained results suggest that using polyarylamine-type HTLs and simple single-phase perovskite compositions paves a way for designing stable and efficient perovskite solar cells.
关键词： stable HTL/perovskite interface,interface-induced degradation,light-induced perovskite crystallization,photo-induced degradation,p-i-n perovskite solar cells
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Aqueous Solution Processed Copper Iodide as Hole Transport Material For Planar Inverted Perovskite Solar Cells
摘要： The inorganic carrier transport layers are robust and stable to the environment compared to the organic hole transport layer (HTL). Here, we report on the fabrication of the halide perovskite devices employing CuI as HTL and explored material properties and optoelectronic characterizations. The CuI device demonstrated the device efficiency of 14.1%. The film morphology of CuI is found to have the influence on the perovskite film growth and hence affected on the device parameters. The interface activation energy (EA) ~Eg suggests the recombination activities in the perovskite bulk is dominant. The capacitance analysis revealed the two trap centers of 0.527 eV and 0.332 eV in the perovskite bulk.
关键词： capacitance spectra,interface recombination,defect,copper iodide,halide perovskite
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering, Information and Communication Technologies (CHILECON) - Valparaiso, Chile (2019.11.13-2019.11.27)] 2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering, Information and Communication Technologies (CHILECON) - Explosive detection system based on Leddar sensor and Self-Organizing Maps in controled environments
摘要： Mobile fronthaul is an important network segment that bridges wireless baseband units and remote radio units to support cloud radio access network. We review recent progresses on the use of frequency-division multiplexing to achieve highly bandwidth-efficient mobile fronthaul with low latency. We present digital signal processing (DSP) techniques for channel aggregation and deaggregation, frequency-domain windowing, adjacent channel leak age ratio reduction, and synchronous transmission of both the I/Q waveforms of wireless signals and the control words (CWs) used for control and management purposes. In a proof-of-concept experiment, we demonstrate the transmission of 48 20-MHz LTE signals with a common public radio interface (CPRI) equivalent data rate of 59 Gb/s, achieving a low round-trip DSP latency of <2 μs and a low mean error-vector magnitude (EVM) of ～2.5% after fiber transmission. In a follow-up experiment, we further demonstrate the transmission of 32 20-MHz LTE signals together with CPRI-compliant CWs, corresponding to a CPRI-equivalent data rate of 39.32 Gb/s, in single optical wavelength channel that requires an RF bandwidth of only ～1.6 GHz. After transmission over 5-km standard single-mode fiber, the CWs are recovered without error, while the LTE signals are recovered with an EVM of lower than 3%. Applying this technique to future 5G wireless networks with massive multiple-input multiple-output is also discussed. This efficient mobile fronthaul technique may find promising applications in future integrated fiber/wireless access networks to provide ultrabroadband access services.
关键词： fifth-generation (5G),frequency-division multiplexing (FDM),common public radio interface (CPRI),Cloud radio access network (C-RAN),optical fiber transmission,mobile fronthaul
更新于2025-09-23 15:21:01
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Oxoammonium enabled secondary doping of hole transporting material PEDOT:PSS for high-performance organic solar cells
摘要： Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is one of the most widely used hole transporting materials in organic solar cells (OSCs). Multiple strategies have been adopted to improve the conductivity of PEDOT:PSS, however, effective strategy that can optimize the conductivity, work function, and surface energy simultaneously to reach a better energy alignment and interface contact is rare. Here, we demonstrate that oxoammonium salts (TEMPO+X?) with different counterions can act as facile and novel dopants to realize secondary doping of PEDOT:PSS. The effective charge transfer process achieved between TEMPO+X? and PEDOT:PSS results in enhanced carrier density and improved conductivity of PEDOT:PSS. Moreover, different counterions of TEMPO+X? can tune the work function and surface energy of PEDOT:PSS, enabling improved device performances. The resulting device with PM6:Y6 as the active layer shows a high power conversion efficiency (PCE) over 16%. Moreover, this doping strategy can also be applied to other conjugated polymers such as poly(3-hexylthiophene). This work provides a promising strategy to tune the properties of conjugated polymers through doping, thus effectively boosting the performance of organic solar cells.
关键词： interface modification,multi-functional secondary doping,organic solar cells,oxoammonium,PEDOT:PSS
更新于2025-09-23 15:21:01
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Interface and Strength of Laser Impact Welding of Fe-Based Nanocrystalline Alloys to Aluminum
摘要： Fe-based nanocrystalline alloys have the characteristics of low power consumption, corrosion resistance and good magnetic stability, while pure Al is characterized by good electrical conductivity, high reflectivity and non-magnetism. To combine the respective performance advantages of the two materials, the welding of Fe-based nanocrystalline alloy foil and Al foil was realized by laser impact spot welding. In addition, the microstructure and mechanical properties of welded joints with different standoff distance were observed and tested. The results show that with the increase in standoff distance, the plastic deformation of the flyer surface will be more serious. When the standoff distance increases gradually (0.1 mm–0.2 mm–0.3 mm), the welding interface will transit from straight interface to wavy interface and finally to wavy interface with local melting zone. The maximum tensile force of the welded sample will increase with the increase in the thickness of the flyer.
关键词： Tensile force,Laser impact spot welding,Wave interface,Fe-based nanocrystalline alloys
更新于2025-09-23 15:21:01
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Interface Engineering of CsPbBr <sub/>3</sub> Nanocrystal Light-Emitting Diodes via Atomic Layer Deposition
摘要： Perovskite nanocrystal (PNC) suffers from solution corrosion and water/oxygen oxidation when used in light-emitting diodes (LEDs). Atomic layer deposition (ALD) is applied to introduce Al2O3 infilling and interface engineering for the CsPbBr3 nanocrystal emission layers, and the inorganic electron transport layer-based CsPbBr3–ZnMgO LED device is fabricated. The introduction of Al2O3 ALD layers significantly improves the tolerance of CsPbBr3 PNC thin films to polar solvents ethanol of ZnMgO during spin coating. The operation lifetime of ALD-treated CsPbBr3 PNC–ZnMgO LED is prolonged to about two orders of magnitude greater than that of the CsPbBr3 PNC-TPBi LED device with a largely improved external quantum efficiency (EQE) value. Moreover, the infilling of Al2O3 into the CsPbBr3 layer boosts the carrier mobility for more than 40 times inside the light-emission layer. However, the interfacial carrier transport between different functional layers is hindered by the insulated Al2O3 layer, which provides an effective barrier for excess electron transport. Such a favorable band alignment facilitates the carrier balance of the device and contributes to the improved electroluminescent performance of the device with ALD Al2O3 interface engineering, which is further supported by theoretical device modeling. Herein, a facile method is provided to fabricate PNC-LED devices with both high efficiency and long-term lifetime.
关键词： light emitting diodes,working stability,interface engineering,atomic layer deposition,CsPbBr3 perovskite nanocrystals
更新于2025-09-23 15:21:01
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Efficiency Enhancement of Cu(In,Ga)(S,Se)2 Solar Cells by Indium-doped CdS Buffer Layer
摘要： Improving power conversion efficiency of photovoltaic devices has been widely investigated, however, most of researches mainly focus on the modification of the absorber layer. Here, we present an approach to enhance the efficiency of Cu(In,Ga)(S,Se)2 (CIGSSe) thin-film solar cells simply by tuning the CdS buffer layer. The CdS buffer layer was deposited by chemical bath deposition. Indium doping was done during the growth process by adding InCl3 into the growing aqueous solution. We show that the solar cell efficiency is increased by properly Indium doping. Based on the characteristics of the single CdS (with or without In-doping) layer and of the CIGSSe/CdS interface, we conclude that the efficiency enhancement is attributed to the interface-defect passivation of heterojunction, which significantly improves both open circuit voltage and fill factor. The results were supported by SCAPS simulations, which suggest that our approach can also be applied to other buffer systems.
关键词： CdS buffer layer,interface passivation,SCAPS simulations,Indium doping,CIGSSe-based solar cell
更新于2025-09-23 15:21:01
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Performance enhancement of inverted perovskite solar cells through interface engineering by TPD based bidentate self-assembled monolayers
摘要： Perovskite solar cells (PSCs) have recently appeared as a promising photovoltaic technology and attracted great interest in both photovoltaic industry and academic community. Numerous active researches related to the material processing and operational aspects of device fabrication are under progress since PSCs have a great potential for attaining higher performance compared to that of other solar cell technologies. In particular, interfacial engineering is a crucial issue for obtaining high efficiency in solar cells where perovskite absorber layer is deposited between hole and electron transport layers. In inverted type architecture, PEDOT:PSS is used as both hole transport layer and surface modifier; but unfortunately, this material bears instability due to its acidic nature. Thus, self-assembled monolayers (SAMs) not only are considered as suitable alternative, but also their application is regarded as an efficient and cost effective method to modify electrode surface since it provides a robust and stable surface coverage. In this context, we have employed two novel N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD) based SAM molecules to customize indium tin oxide (ITO) surface in inverted type PSCs. Furthermore, fine-tuning of spacer groups enables us to study device performance depending on molecular structure. This study proposes promising materials for anode interface engineering and provides a feasible approach for production of organic semiconductor based SAMs to achieve high performance PSCs.
关键词： Interface,ITO,TPD,Bidentate,Self-assembled monolayer,Perovskite solar cell
更新于2025-09-23 15:21:01