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- 摘要
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- 实验方案
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Introduction to Quantum Electronics and Nonlinear Optics || Field Interaction with a??Free Chargesa??
摘要： The chapter discusses the interaction of electromagnetic fields with 'free charges' in plasma, focusing on the kinetic equation, cyclotron resonance, and fundamental absorption in semiconductors. It explores the classical and quantum mechanical descriptions of plasma behavior under external fields, including the effects of magnetic fields on electron motion and the absorption of electromagnetic waves by semiconductors.
关键词： semiconductors,plasma,cyclotron resonance,electromagnetic fields,free charges,kinetic equation,fundamental absorption
更新于2025-09-23 15:19:57
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Highly luminescent blue-emitting In <sub/>1a??x</sub> Ga <sub/>x</sub> P@ZnS quantum dots and their applications in QLEDs with inverted structure
摘要： In order to resolve the issues of uncontrollably high reactivity of tris(trimethylsilyl)phosphine, widely used P precursor, and very low solubility of metal halide precursors in non-coordinating solvent with ligands in the synthesis of environmentally benign III-V quantum dots, we created bis(trimethylsilyl)phosphine, HP(TMS)2, new P precursor with controllable reactivity and new metal complex precursors (Indium-trioctylphosphine, In-TOP; Ga-TOP; Zn-TOP) soluble in octadecene, non-coordinating solvent with dodecanethiol, C12SH. Another challenging issue with III-V quantum dots is to generate highly luminescent photostable blue-emitting nanaocrystals. We present the way of synthesizing pure III-V In1-xGaxP blue-emitting alloy core in non-coordination solvent. Gallium is introduced in the core to adjust the exciton energy effectively and to lessen lattice mismatch with zinc sulfide shell which contributes to the removal of surface defects and the enhancement of the photostability, and thus enhancing the photoluminescent quantum yield (PLQY) and the high color purity of quantum dots with narrow full width at half maximum (FWHM). The blue-emitting quantum dots, In1-xGaxP@ZnS of outstanding quality (PLQY = 65 %, FWHM = 46 nm) is successfully synthesized with our new P and metal complex precursors. Furthermore, we apply those QDs to fabricate blue-emitting quantum dot light-emitting devices (QLEDs) with the external quantum efficiency of 0.20 % which is the best among the III-V-based blue-emitting QLEDs reported so far.
关键词： III-V semiconductors,Photoluminescence,Blue-emitting,QLEDs,Quantum dots
更新于2025-09-23 15:19:57
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Water-Processed Organic Solar Cells with Open-Circuit Voltages Exceeding 1.3V
摘要： Conjugated polyelectrolytes are commonly employed as interlayers to modify organic solar cell (OSC) electrode work functions but their use as an electron donor in water-processed OSC active layers has barely been investigated. Here, we demonstrate that poly[3-(6’-N,N,N-trimethyl ammonium)-hexylthiophene] bromide (P3HTN) can be employed as an electron donor combined with a water-soluble fullerene (PEG-C60) into eco-friendly active layers deposited from aqueous solutions. Spin-coating a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) layer prior to the P3HTN:PEG-C60 active layer deposition considerably increases the open-circuit voltage (Voc) of the OSCs to values above 1.3 V. Along with this enhanced Voc, the OSCs fabricated with the PEDOT:PSS interlayers exhibit 10-fold and 5-fold increases in short-circuit current density (Jsc) with respect to those employing bare indium tin oxide (ITO) and molybdenum trioxide coated ITO anodes, respectively. These findings suggest that the enhanced Jsc and Voc in the water-processed OSCs using the PEDOT:PSS interlayer cannot be solely ascribed to a better hole collection but rather to ion exchanges taking place between PEDOT:PSS and P3HTN. We investigate the optoelectronic properties of the newly formed polyelectrolytes using absorption and photoelectron spectroscopy combined with hole transport measurements to elucidate the enhanced photovoltaic parameters obtained in the OSCs prepared with PEDOT:PSS and P3HTN.
关键词： frontier orbitals,organic semiconductors,organic solar cells,conjugated polyelectrolytes,sustainable fabrication
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - Atlanta, GA, USA (2019.7.7-2019.7.12)] 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - A Unit-Cell Discontinuous Galerkin Scheme for Analyzing Plasmonic Photomixers
摘要： Disordered ionic-bonded transition metal oxide thin-film transistors (TFTs) show promise for a variety of dc and RF switching applications, especially those that can leverage their low-temperature, substrate-agnostic process integration potential. In this paper, enhancement-mode zinc-oxide TFTs were fabricated and their switching performance evaluated. These TFTs exhibit the drain-current density of 0.6 A/mm and minimal frequency dispersion, as evidenced by dynamic current–voltage tests. A high-frequency power switch figure of merit RON QG of 359 mΩ · nC was experimentally determined for 0.75-μm long-channel devices, and through scaling 45.9 mΩ · nC is achievable for 11 V-rated devices (where RON is ON-state drain–source resistance, and QG is gate charge). An RF switch cutoff frequency fc of 25 GHz was measured for the same 0.75-μm TFT, whereas fc exceeding 500 GHz and power handling in the tens of watts are projected with optimization.
关键词： zinc oxide,dc switch,Cutoff frequency,pulse measurements,gate charge,monolithic ICs,RF switch,ionic semiconductors,thin-film transistors (TFTs)
更新于2025-09-23 15:19:57
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Structural and Optical Properties of Zn <sub/>1‐</sub><i> <sub/>x</sub></i> Mg <i> <sub/>x</sub></i> O Prepared by Calcination of ZnO + Mg(OH) <sub/>2</sub> after Hydro Micro Mechanical Activation
摘要： Zn1-xMgxO microcrystals are produced in the 0.15 (cid:2) x (cid:2) 1 composition range by calcination of ZnO + Mg(OH)2 after hydro micro mechanical activation according to the patent WO2018065735A1. The structural properties of the samples have revealed the cohabitation of wurtzite and rock-salt phases for x values ranging from 0.15 up to 0.6 with a clear increase of the proportion of cubic phase with x. A single cubic phase is observed in the range 0.66 (cid:2) x < 1. From the purity of these samples produced at very low cost, it is expected that they will be used as precursors for growth of advanced light emitters integrated into an already existing process as they exhibit exceptionally e?cient (and robust with T) light emission in the ultraviolet region.
关键词： optical properties,oxides,ultraviolet emission,wide bandgap semiconductors
更新于2025-09-23 15:19:57
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Engineering Efficient Photon Upconversion in Semiconductor Heterostructures
摘要： Photon upconversion is a photophysical process in which two low-energy photons are converted into one high-energy photon. Photon upconversion has broad appeal for a range of applications from biomedical imaging and targeted drug-release to solar energy harvesting. Current upconversion nanosystems, including lanthanide-doped nanocrystals and triplet-triplet annihilation (TTA) molecules, have achieved upconversion quantum yields of order 10-30%. However, the performance of these materials is hampered by inherently narrow absorption cross-sections and fixed energy levels originating in atomic, ionic, or molecular states. Semiconductors, on the other hand, have inherently wide absorption cross-sections. Moreover, recent advances enable the synthesis of colloidal semiconductor nanoparticles with complex heterostructures that can control band alignments and tune optical properties. We synthesize and characterize a three-component heterostructure that successfully upconverts photons under continuous-wave (CW) illumination and solar-relevant photon fluxes. The heterostructure is composed of two cadmium selenide (CdSe) quantum dots (QDs), an absorber and emitter, spatially separated by a cadmium sulfide (CdS) nanorod (NR). We demonstrate that the principles of semiconductor heterostructure engineering can be applied to engineer improved upconversion efficiency. We first eliminate electron trap-states near the surface of the absorbing QD and then tailor the bandgap of the NR such that charge carriers are funneled to the emitting QD. When combined, these two changes result in a 100-fold improvement in photon upconversion performance.
关键词： solar energy,semiconductors,upconversion,coupled quantum dots,nanostructures,core/rod/emitter
更新于2025-09-23 15:19:57
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Conducting Polymers || Electrical Properties of Polymer Light-Emitting Devices
摘要： In this chapter, we present a brief introduction to semiconducting properties of conjugated polymers and the motivation to apply this class of materials in electronic/optoelectronic devices such as polymer light-emitting diodes (PLEDs). We describe, in detail, the operating mechanisms of PLEDs, with particular focus on the effects of charge injection and transport and their dependence on the external electric field and temperature. The mechanisms of current injection from the electrodes into the organic semiconductor are initially treated using traditional models for thermionic emission and tunnelling injection. More recent models considering the influence of metal/semiconductor interface recombination and of energetic and spatial disorder in the injection currents are also introduced and discussed. In addition, models considering space-charge-limited currents and trap-filling-limited currents are employed to describe the charge transport characteristics in the bulk. Furthermore, we present a brief discussion on ideas concerning the effects of the disorder on the charge-carrier transport behaviour.
关键词： space-charge-limited currents,conjugated polymers,polymer light-emitting diodes,organic semiconductors,electrical properties
更新于2025-09-19 17:15:36
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A quantitative structure–property study of reorganization energy for known p-type organic semiconductors
摘要： Intramolecular reorganization energy (RE), which quantifies the electron-phonon coupling strength, is an important charge transport parameter for the theoretical characterization of molecular organic semiconductors (OSCs). On a small scale, the accurate calculation of the RE is trivial; however, for large-scale screening, faster approaches are desirable. We investigate the structure–property relations and present a quantitative structure–property relationship study to facilitate the computation of RE from molecular structure. To this end, we generated a compound set of 171, which was derived from known p-type OSCs built from moieties such as acenes, thiophenes, and pentalenes. We show that simple structural descriptors such as the number of atoms, rings or rotatable bonds only weakly correlate with the RE. On the other hand, we show that regression models based on a more comprehensive representation of the molecules such as SMILES-based molecular signatures and geometry-based molecular transforms can predict the RE with a coefficient of determination of 0.7 and a mean absolute error of 40 meV in the library, in which the RE ranges from 76 to 480 meV. Our analysis indicates that a more extensive compound set for training is necessary for more predictive models.
关键词： molecular signatures,molecular transforms,reorganization energy,organic semiconductors,quantitative structure–property relationship
更新于2025-09-19 17:15:36
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Analysis of the charge transfer and separation in electrically doped organic semiconductors by electron spin resonance spectroscopy
摘要： We investigated the charge generation mechanism of electrically doped organic semiconductors (OSs) by electron spin resonance (ESR) analysis. ESR spectroscopy was used to successfully evaluate the radical density of p-doped OSs to estimate the charge transfer efficiency (CTE) of various doped systems. The results showed that the CTE is efficient close to 100% if the dopant molecules are homogenously dispersed and the energy difference (?E) between the highest occupied molecular orbital (HOMO) level of the host molecule and lowest unoccupied molecular orbital (LUMO) level of the p-dopant is large. The charge separation efficiency to form free carriers from the radicals is rather low (less than 12% in this study) and is a dominant factor controlling the charge generation efficiency (CGE). An organic dopant molybdenum tris[1,2-bis(trifluoromethyl)ethane-1,2-dithiolene] turns out to be an efficient dopant with the CGE of 9.7% due to high CTE originating from homogenous dispersion of the organic p-dopants and low LUMO level, i.e., large ?E.
关键词： charge generation efficiency,p-dopant,charge transfer,electron spin resonance spectroscopy,Organic semiconductors,charge separation
更新于2025-09-19 17:15:36
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New C–H Arylation Saves Steps for Small-Molecule Organic Semiconductors
摘要： New C–H Arylation Saves Steps for Small-Molecule Organic Semiconductors. Significance: Semiconductors based on organic molecules are appealing because of their applicability in the fabrication of various optoelectronic devices. They are particularly interesting because of their diverse molecular design, well-defined conjugation lengths, and easier modification of functional groups. In this report, Liu and co-workers developed a direct C–H (hetero)arylation reaction that enables the synthesis of semiconducting organic molecules by coupling various useful end groups to core-type building blocks in fewer steps. Comment: The authors optimized the reaction and investigated the scope in the synthesis of donor-type end groups, acceptor-type end groups, and various hybrid-type end groups. To demonstrate the utility of the reaction, they synthesized two new D–A–π-A′ organic sensitizers, CYL-3 and CYL-4 in fewer steps than is conventionally required. The dye-sensitized solar cells fabricated by using these organic sensitizers showed an impressive power conversion efficiency corresponding to 6.02% and 4.76%, respectively.
关键词： C–H arylation,organic semiconductors,thiophenes
更新于2025-09-19 17:15:36