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Potassium Doping Effect on the Photovoltaic Performance of Perovskite Solar Cells
摘要： We have fabricated a series of potassium-doped (K-doped) perovskite solar cells (PSCs). Structural investigations of the developed PSCs have shown that alkai doping affects the perovskite layer structure and morphology with the increase of the crystallite size and surface uniformity. K-doped samples exhibite higher photovoltaic (PV) performance and improved operational stability compared to the control series of undoped PSCs, due to retarded recombination processes.
关键词： solar cell,perovskite,doping
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 2nd International Conference on Knowledge Innovation and Invention (ICKII) - Seoul, Korea (South) (2019.7.12-2019.7.15)] 2019 IEEE 2nd International Conference on Knowledge Innovation and Invention (ICKII) - A Physical Threshold Voltage Model of Nanoscale Ultra-thin Body Ultra-thin Box SOI MOSFETs with a Gaussian Doping Profile
摘要： An insightful study of the virtual cathode is performed for the nanoscale ultra-thin body ultra-thin box SOI MOSFETs with a vertical Gaussian doping. And the physical, compact threshold voltage model is derived based on an analytical solution of two-dimensional Poisson equation with the evanescent-mode analysis. The accuracy of the model has been verified by 2D numerical device simulations using Sentaurus Technology Computer-Aided Design (TCAD) from Synopsys. Applying the newly developed model, the threshold voltage sensitivities to channel length, silicon-film thickness, buried-oxide thickness, and the channel doping concentration have been comprehensively investigated. Good agreements are achieved. Model predictions indicate that the individual UTBB-SOI MOSFET with a non-uniform doping profile is feasible at 10 nm scale. This work has both theoretical and practical significance and provide aids in promoting theoretical modeling research and applications of new UTBB-SOI based devices.
关键词： UTBB-SOI MOSFET,Analytical model,Gaussian doping,Virtual cathode
更新于2025-09-23 15:21:01
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Regulatory Preparation of N/S Doped Carbon Quantum Dots and Their Applications as Fe(III) Ion Sensors
摘要： The nitrogen-sulfur co-doped fluorescent carbon quantum dots (N/S-CQDs) were synthesized from sulfanilic acid. The fluorescence emission was independent of the excitation wavelength. In this experiment, the carbonization degree of the precursors was adjusted by solvent-thermal method to affect the sp2 conjugated dimension of CQDs, thus affecting the fluorescence performance of CQDs. They are well dispersed in water and ethanol, and have high selectivity for Fe3 +. The detection range is 0.025 ～ 0.4 mmol/L, and the detection limit is about 2.549 μmol/L. The CQDs prepared in this experiment emit light indirectly through the surface defect state. When CQDs is illuminated by light, the carriers generated by photons will emit light at a very fast speed due to the surface defect state, so the excited electrons in CQDs can be easily transferred to Fe3 +, making the surface of CQDs more complete, thus leading to the quenching of CQDs fluorescence.
关键词： Fe3 + sensor,Nitrogen and sulfur co-doping,carbon quantum dots,Fluorescence
更新于2025-09-23 15:21:01
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A Review: Recent Advances in Preparations and Applications of Heteroatom-Doped Carbon Quantum Dots
摘要： Carbon quantum dots (CQDs) are widely used in optoelectronic catalysis, biological imaging, and ion probes owing to their low toxicity, stable photoluminescence, and ease of chemical modification. However, the low fluorescence yield and monochromatic fluorescence of CQDs limit their practical applications. This review summarizes the commonly used approaches for improving the fluorescence efficiency of CQDs doped with non-metallic (heteroatoms) elements. Herein, three types of heteroatom-doped CQDs have been investigated: (1) CQDs doped with a single heteroatom; (2) CQDs doped with two heteroatoms; and (3) CQDs doped with three heteroatoms. The limitations and future perspectives of doped CQDs from the viewpoint of producing CQDs for specific applications, especially for bioimaging and light emitting diodes, have also been discussed herein.
关键词： Carbon quantum dots,Doping,Photoluminescence,Heteroatoms
更新于2025-09-23 15:21:01
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Growth mechanisms of F4-TCNQ on inorganic substrates and nanostructures
摘要： The organic semiconductor tetrafluorotetracyanoquinodimethane (F4-TCNQ) is a promising candidate for the doping of organic semiconductors, two-dimensional materials and inorganic compounds, such as ZnO, and also to enhance the charge carrier injection at contacts in organic electronics. In order to evaluate its applicability as a functionalization material or as an electrically active part in devices, we present a systematic study on the growth mode of F4-TCNQ beyond the first few monolayers on different inorganic substrates that cover a broad variety regarding their physical, chemical and morphological surface properties. The materials used are silicon, silicon carbide, graphene on silicon, sapphire, nanocrystalline diamond, as well as gallium nitride (GaN) layers and nanowire arrays. While the surface termination influences the shape and morphology of the islands of F4-TCNQ which form on all substrates investigated, no significant dependence of the growth mode on the substrate doping type and concentration is observed. GaN nanowires are found to act as nucleation sites for F4-TCNQ islands and to be covered by few monolayers of F4-TCNQ forming a closed coaxial shell. In conclusion, F4-TCNQ is identified to nucleate via Stranski-Krastanov growth consisting of monolayers and islands of different size and shape. The findings in this work provide basic growth information for the implementation of F4-TCNQ as functionalization material for nanowire-based applications.
关键词： GaN nanowires,surface functionalization,growth mode,organic semiconductors,organic electronics,surface doping,F4-TCNQ
更新于2025-09-23 15:21:01
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THz cutoff frequency and multifunction Ti 2Ba2Ca2Cu3O10/GaAs photonic bandgap materials
摘要： By using the transfer matrix method (TMM), we theoretically explore the transmittance properties and cuto? frequency of one-dimensional photonic crystal (1DPCs) within the terahertz frequency region. The present structure consists of high-temperature superconductor and semiconductor layers. The results of the calculations represent the e?ects of various parameters on the cuto? frequency. We have used the two-?uid model as well as the Drude model to describe the permittivity of superconductor and semiconductor. Further, we consider that the permittivity of both the materials is depending on the hydrostatic pressure. The present results show that with the increasing of di?erent parameters as the operating temperature, the thickness of semiconductor, and the ?lling factor of semiconductor, then the cuto? frequency shift to lower frequencies regions. By the increasing of superconductor thickness, hydrostatic pressure, doping concentration and ?lling factor of the superconductor, we found the cuto? frequency shifts to higher frequency regions. These results indicate that cuto? frequency can be modi?ed through these di?erent parameters. Finally, the present design could be useful for many optical systems as the optical ?lter, re?ector and photoelectronic applications in the Terahertz regime.
关键词： Cuto? frequency,transfer matrix method,photonic crystal,doping concentration,hydrostatic pressure,two-?uid model,Drude model
更新于2025-09-23 15:21:01
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: <i>Ab initio</i> and Monte Carlo approaches
摘要： The effects of nonmagnetic impurity doping on magnetic and ferroelectric properties of multiferroic delafossite CuCrO2 are investigated by means of density functional theory calculations and Monte Carlo simulations. Density functional theory calculations show that replacing up to 30% of Cr3+ ions by Ga3+ ones does not significantly affect the remaining Cr-Cr superexchange interactions. Monte Carlo simulations show that CuCr1?xGaxO2 preserves its magnetoelectric properties up to x ≈ 0.15 with a spiral ordering, while it becomes disordered at higher fractions. Antiferromagnetic transition shifts towards lower temperatures with increasing x and eventually disappears at x ≈ 0.2. Our simulations show that Ga3+ doping increases the Curie-Weiss temperature of CuCr1?xGaxO2, which agrees well with experimental observations. Moreover, our results show that the incommensurate ground-state configuration is destabilized by Ga3+ doping under zero applied field associated with an increase of frustration. Finally, coupling between noncollinear magnetic ordering and electric field is reported for x ≤ 0.15 through simulating P -E hysteresis loops, which leads to ferroelectricity in the extended inverse Dzyaloshinskii-Moriya model.
关键词： CuCrO2,multiferroic,Monte Carlo simulations,ferroelectric properties,magnetic properties,density functional theory,delafossite,Ga doping
更新于2025-09-23 15:21:01
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Wafer Scale Graphene Field Effect Transistors on Thin Thermal Oxide
摘要： In this study, we present the feasibility to fabricate back-gated graphene field-effect transistors (GFETs) on 10 nm thermal SiO2 substrate. Here, we compare the mobility of graphene devices at different locations of the transferred CVD graphene. We observed that there is a n-type doping of the graphene devices with Dirac points within ± 0.5 V from an ideal value of 0 V. The downscaling of the back-gate dielectric thickness reduces the operating voltage range, commonly required for low power electronics, and the devices are stable during operation in air under ambient conditions. The extracted contact resistance is comparable to the earlier reports found in literature and this provides a feasibility to fabricate low power futuristic graphene based nanoelectronics.
关键词： CVD graphene,n-type doping,thermal SiO2,mobility,Dirac points,low power electronics,field-effect transistors,graphene,contact resistance
更新于2025-09-23 15:21:01
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Influence of boron doping amount on properties of ZnO:B films grown by LPCVD technique and its correlation to a-Si:H/??c-Si:H tandem solar cells
摘要： Boron-doped ZnO:B (BZO) films with various doping levels have been prepared on large-area substrates by low pressured chemical vapor deposition technique. The influence of doping amount on electrical and optical properties of BZO films has been investigated. It is found that ZnO phase synthesis is hardly affected when the doping gas flow varies from 25 to 100 sccm, but the preferential orientation of grain growth is influenced progressively. It is interesting that there should be a threshold value of doping gas flow of 75 sccm that will cause an abrupt reduction in grain size of BZO and therefore dramatically weakens the light-scattering capacity of the film. It is also noted that the boron atoms doped in BZO films are partly electrically active, and moreover, the heavier doping level, the more inactive B atoms, which not only reduces carrier mobility, but also boosts a stronger light absorption due to enhanced impurity scattering. When the doping gas flow is 75 sccm, the BZO film can achieve a proper comprehensive property with a Rsq of 15.2 Ω/□, an average haze of 21.3% and an average TT of 80.2%. Using this film as the front electrode of a-Si:H/μc-Si:H solar cell, the optimum performance of the solar cell with a Jsc of 12.68 mA/cm2, a Voc of 1.385 mV, and an initial efficiency (η) of 11.83% was obtained.
关键词： a-Si:H/μc-Si:H tandem solar cells,Boron-doped ZnO:B films,doping amount,LPCVD technique,electrical and optical properties
更新于2025-09-23 15:21:01
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A Facile Approach to the Synthesis of n-Type π-Conjugated Hyperbranched Polymers
摘要： A facile approach for the synthesis of an n-type π-conjugated hyperbranched polymer, namely hyperbranched polypyridinebenzene, is proposed based on the copolymerization of 1,3,5-tribromobenzene (BeBr3) and 2,5-dibromopyridine via chain-growth condensation polymerization catalyzed by Ni(dppp)Cl2. The use of BeBr3 as a branching unit simplifies the synthesis of n-type π-conjugated hyperbranched polymers, compared with a similar hyperbranched polymer prepared from 2,4,6-tribromopyridine (PyBr3) and 2,5-dibromopyridine requiring a lengthy synthetic route to give the starting material PyBr3. The results of UV-Vis spectroscopy and cyclic voltammetry suggest that our synthesized polymer retains its hyperbranched structure, which is beneficial in electrochemical doping.
关键词： Cross-coupling,Doping,Polypyridine,Chain-growth condensation
更新于2025-09-23 15:21:01