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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • electron-transparent membranes
  • micropump
  • field emission electron source
  • ion source
  • ion mobility spectrometry
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Wroclaw University of Science and Technology
209 条数据
?? 中文（中国） ▾

  • Effects of non-halogenated solvent on the main properties of a solution-processed polymeric thin film for photovoltaic applications: a computational study

    摘要： Organic photovoltaic (OPV) devices reached high solar conversion efficiencies but they are usually processed using halogenated toxic solvents. Hence, before OPV devices can be mass-produced by industrial processing, it would be desirable to replace those solvents with eco-friendly ones. Theoretical tools may be then a powerful ally in the search for those new solvents. In order to better understand the mechanisms behind the interaction between solvent and polymer, classical molecular dynamics (MD) calculations was used to produce a thin film of poly(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl (PTB7-Th), processed using two different solvents. The PTB7-Th is widely applied as a donor material in OPVs. The first solvent is the ortho-dichlorobenzene (o-DCB), which is a highly toxic solvent widely used in lab-scale studies. The second solvent is the ortho-methylanisole (o-MA), which is an eco-friendly solvent for organic photovoltaic (OPV) manufacturing. Here we use a solvent evaporation protocol to simulate the formation of the PTB7-Th film. We demonstrate that our theoretical MD calculations were able to capture some differences in macroscopic properties of thin films formed by o-DCB or o-MA evaporation. We found that the interaction of the halogenated solvent with the polymer tends to break the bonds between the lateral thiophenediyl groups and the main chain. We show that those defects may create traps that can affect the charge transport and also can be responsible for a blue shift in the absorption spectrum. Using the Monte Carlo method, we also verified the influence of the resulting MD morphology on the mobility of holes. Our theoretical results showed a good agreement with the experimental measurements and both demonstrate that o-MA can be used to make polymer thin films without any loss of key properties for the device performance. The findings here highlights the importance of theoretical results as a guide to the morphological optimization of green processed polymeric films.

    关键词： Solvent evaporation,PTB7-Th,Molecular dynamics,Organic photovoltaic,Halogenated solvents,Eco-friendly solvents,Hole mobility

    更新于2025-09-23 15:19:57

  • On the use of multiple stacked active layers in organic photovoltaic cells

    摘要： In the field of organic photovoltaic cells (OPVs), ternary planar heterojunction allows widening absorption range. Optimization of the energy levels at the organic interfaces is the first task to achieve in order to obtain OPVs with high efficiency. In ternary OPVs, carrier mobility, charge transfer and presence of energy transfer are determinant. Here, we compare the performances of different, binary (electron donor/fullerene) and ternary (electron donor/ambipolar material/fullerene) combinations of small organic molecules in planar heterojunction (PHJ) cells. We chose the different ED molecules in order to investigate the different possible band scheme alignments. The study shows that if the open circuit voltage (Voc) is limited by the energy levels of the outer layers, i.e. the difference between the lowest unoccupied molecular orbital (LUMO) of the electron acceptor and the highest occupied molecular orbital (HOMO) of the outer electron donor layer, the energy loss can be smaller than 0.2 eV. If efficient ternary OPVs need global energy offset higher than the exciton energy to separate the charges of the exciton, the distribution of this offset between DLUMO and DHOMO is not critical. The mobility value of the carriers in the intercalated layer is determinant in obtaining performance of OPVs. Overlap between the photoluminescence of ED and the optical absorption of EDA is primordial for good energy transfer. The highest OPV efficiency improvement is obtained with organic materials such as ED and EDA that have the same HOMO and similar hole mobility which give homogeneous thin layers.

    关键词： organic photovoltaic cells,energy levels,energy transfer,carrier mobility,charge transfer,ternary planar heterojunction

    更新于2025-09-23 15:19:57

  • 3a??Dimensional Charge Transport Pathway in Organic Solar Cells via Incorporation of Discotic Liquid Crystal Columns

    摘要： 2,3,6,7,10,11-hexaacetoxytriphenylene (HATP) as a discotic liquid crystals with high mobility can aggregate into columns structure on PEDOT:PSS in organic solar cells. HATP columns facilitate the formation of 3-dimensional charge transport pathway, which increase the intermolecular charge transport and mobility. Additionally, the triplet exciton, trap state and bimolecular recombination is suppressed. Thus, the JSC is increased significantly for (non-) fullerene system.

    关键词： discotic liquid crystal,organic solar cells,mobility,columnar structure,3-dimensional charge transport

    更新于2025-09-23 15:19:57

  • Fermi velocity renormalization in graphene probed by terahertz time-domain spectroscopy

    摘要： We demonstrate terahertz time-domain spectroscopy (THz-TDS) to be an accurate, rapid and scalable method to probe the interaction-induced Fermi velocity renormalization νF* of charge carriers in graphene. This allows the quantitative extraction of all electrical parameters (DC conductivity σDC, carrier density n, and carrier mobility μ) of large-scale graphene films placed on arbitrary substrates via THz-TDS. Particularly relevant are substrates with low relative permittivity (< 5) such as polymeric films, where notable renormalization effects are observed even at relatively large carrier densities (> 1012 cm-2, Fermi level > 0.1 eV). From an application point of view, the ability to rapidly and non-destructively quantify and map the electrical (σDC, n, μ) and electronic (νF*) properties of large-scale graphene on generic substrates is key to utilize this material in applications such as metrology, flexible electronics as well as to monitor graphene transfers using polymers as handling layers.

    关键词： Graphene,THz-TDS,Fermi Velocity Renormalization,Mobility Mapping,Flexible Substrates

    更新于2025-09-23 15:19:57

  • Investigation of physical properties of F-and-Ga co-doped ZnO thin films grown by RF magnetron sputtering for perovskite solar cells applications

    摘要： F-and-Ga co-doped ZnO films were sputter-deposited on glass substrates by RF magnetron sputtering method. The fabricated films were characterized by different techniques. It was found that all the films were poly-crystalline with a hexagonal wurtzite structure with a c-axis preferred orientation of growth. The effect of the substrate temperature on the surface morphology, electrical and optical properties of the films was also investigated. The optimal growth temperature was found to be 440 oC which led to the optimal film with the resistivity of 6.81 × 10?4 Ωcm, carrier concentration of 2.61 × 1020 cm?3, mobility of 35.1 cm2/V, over-90% transmittance in the region of 400–1200 nm and a wide optical bandgap of 3.49 eV. This optimal film was employed in as the front contact in perovskite solar cells and resulted in a high power-conversion efficiency of 15.32%. This indicates that such a film can be promisingly useful for high-performance thin-film solar cells.

    关键词： High mobility,Thin-film solar cells,F-and-Ga co-doped ZnO films,Magnetron sputtering

    更新于2025-09-23 15:19:57

  • [Springer Series on Atomic, Optical, and Plasma Physics] Gaseous Ion Mobility, Diffusion, and Reaction Volume 105 || Summary and Prognosis

    摘要： Gaseous ion mobility, diffusion, and reaction have been studied by swarm techniques for about 120 years. Many important discoveries have been made, including the existence of electrons, ions, and isotopes; verification of quantum mechanics; the NTE equation; the tensorial nature of diffusion coefficients; and the usefulness of DTMS for studying ion–neutral reactions. The chapter reviews the progress in theoretical descriptions, numerical methods, and ab initio calculations of transport coefficients, highlighting the need for further research in molecular ion–neutral systems and the potential of models in understanding gaseous ion data.

    关键词： DTMS,ion–neutral reactions,Boltzmann equation,swarm techniques,gaseous ion mobility,ab initio calculations,diffusion,IMS

    更新于2025-09-23 15:19:57

  • Hall Effect in Germanium Doped with Different Impurities

    摘要： The influence of different impurities on the kinetics of electronic processes in n-Ge?Sb? single crystals is investigated. A substantial decrease in the charge carrier mobility in the region of predominantly impurity scattering (at 77 K) in n-Ge?Sb + Si? crystals, as well as in germanium crystals doped with the rare-earth elements, is detected, and this effect is explained.

    关键词： Hall effect,charge carrier mobility,germanium,Hall coefficient,impurities

    更新于2025-09-19 17:15:36

  • A broadband GaAs pHEMT low noise driving amplifier with current reuse and self-biasing technique

    摘要： A K/Ka-band two-stage low noise driving ampli?er using a 0.15 lm GaAs pHEMT for low noise technology is designed and fabricated. In order to achieve broadband driving capability with low power consumption, current reuse technique is adopted to feed both transistors with the same DC power supply, which theoretically cuts the total current consumption in half. In addition, self-biasing technique is utilized to minimize both external power supply pads and chip footprint, which reduces the number of supply pads to a minimum of two (1 power pad and 1 ground pad). The circuit topology analysis and design procedures are also presented with an emphasis on noise ?gure and P1dB optimization. The low noise driving ampli?er demonstrates a - 3 dB bandwidth of wider than 11 GHz, a power gain of 17 dB, an in-band mean noise ?gure of 2.2 dB and an in-band mean output P1dB of 6 dBm. The DC power consumption is 9.1 mA@3.3 V power supply. The chip size is 1 mm 9 1.5 mm with only 1 external DC feed pad (3.3 V) and 1 ground pad (0 V). With the performance comparable to typical two-stage dual-bias low noise driving ampli?er counterparts, the proposed MMIC is more attractive to chip/system users in volume-limited and power-contrained applications.

    关键词： Ka-band,Pseudomorphic high electron mobility transistor (pHEMT),GaAs,Low noise driving ampli?er,Monolithic microwave integrated circuit (MMIC)

    更新于2025-09-19 17:15:36

  • Carrier reduction studies of type-II superlattice materials for very long wavelength infrared sensing

    摘要： There are continuing efforts to develop type-II superlattice (SL) materials for very long wavelength infrared (VLWIR) detector applications. However, the SLs have high residual electron background doping densities that depend on SL growth conditions, which lead to shorter minority carrier lifetime and lower performance parameters than theoretically predicted. In this study, the authors compare the technical advantages of using InAs/GaInSb over InAs/GaSb SL with respect to reducing the electron doping levels. Our temperature-dependent electrical transport measurements show that the InAs/GaInSb SL design has a lower electron density than the InAs/GaSb SL with the same bandgap and have electron densities (mobilities) on the order of the mid 1011 cm?2 (25 000 cm2/V s). Since small period InAs/GaInSb SLs also produce greater Auger recombination suppression for a given VLWIR gap than the large period InAs/GaSb SL, the InAs/GaInSb SL appears to be a better candidate for long lifetime IR materials for future very long wavelength infrared devices.

    关键词： very long wavelength infrared,mobility,InAs/GaSb,Auger recombination,InAs/GaInSb,type-II superlattice,carrier reduction,electron doping

    更新于2025-09-19 17:15:36

  • [IEEE 2018 9th International Conference on Computer Aided Design for Thin-Film Transistors (CAD-TFT) - Shenzhen, China (2018.11.16-2018.11.18)] 2018 9th Inthernational Conference on Computer Aided Design for Thin-Film Transistors (CAD-TFT) - High mobility metal-oxide thin film transistors with IGZO/In<inf>2</inf>O<inf>3</inf> dual-channel structure

    摘要： High-performance Self-aligned top-gate thin film transistors with dual-channel have been successfully fabricated on glass substrate. The dual-layer channel is composed of In2O3 and IGZO layers. The introduction of the In2O3 thin layer greatly improves the electrical characteristics of the self-aligned top-gate thin film transistors. In comparison, the dual-channel TFT shows higher filed-effect mobility (34.3cm2/Vs) than single-layer a-IGZO TFT (10.2cm2/Vs). Apart from that we obtain an on/off current ratio of 106, a steep subthreshold swing voltage of 0.44V/decade and a threshold voltage of -3.35V. This enhancement can be attributed to the In2O3 thin layer which offers a higher carrier concentration, thereby maximizing the charge accumulation, generating high carrier mobility and turning the threshold voltage negative.

    关键词： Self-aligned top-gate TFT,IGZO,uniformity,high mobility,threshold voltage,In2O3

    更新于2025-09-19 17:15:36