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- 实验方案
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Interface engineering with a novel n-type small organic molecule for efficient inverted perovskite solar cells
摘要： Fullerene derivatives are promising electron transporting materials for low-temperature processed inverted perovskite solar cells (PSCs). However, fullerene derivatives have some disadvantages, e.g. [6,6]-phenyl C61 butyric acid methyl ester (PCBM) has unmanageable morphology, low electron mobility and easily generated non-radiative recombination, which restrict the performance of PSCs. Herein, a novel n-type small organic molecule, homologous perylene diimide tetramer (HPDT), is designed and synthesized in this work to engineer the interface properties by enhancing interface contact, decreasing energetic barrier and recombination losses. HPDT shows suitable energy levels and high electron mobility and thus will increase the electron mobility when interface engineering in the inverted PSCs. Moreover, coating HPDT on top of perovskite prior to the deposition of PCBM is helpful to achieve a homogeneous pinhole-free PCBM layer, leading to enhanced power conversion efficiency from 17.38% up to 19.75% for inverted MAPbI3 PSCs along with a negligible hysteresis. Significantly, our results undoubtedly enable new guidelines in exploring n-type organic small molecules for high-performance PSCs.
关键词： electron transport material,perovskite solar cell,interface engineering,recombination loss
更新于2025-09-11 14:15:04
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Highly flexible and solution-processed organic photodiodes and their application to optical luminescent oxygen sensors
摘要： We present a solution-processed flexible organic photodiode (f-OPD) with a bulk heterojunction (BHJ) structure based on a blend of poly (3-hexylthiophene-2,5-diyl) and 1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61 (P3HT:PCBM). We used Cs2CO3-doped polyethyleneimine ethoxylated (d-PEIE) as the electron transport layer (ETL) material, which significantly improved the electron injection properties of the f-OPD. Compared with f-OPDs with conventional ETL materials such as Cs2CO3, the external quantum efficiency (EQE) of the d-PEIE-based f-OPD was highly improved. Analytical results showed that the d-PEIE reduced the work function of the cathode, thereby facilitating the efficiency of electron injection from the active layer (AL) to the cathode of the f-OPD. In addition, after 10,000 cycles of tensile bending at a bending radius of 5 mm, the normalized ID variation (ID/ID0) in the d-PEIE-based f-OPD remained above 90%, indicating an excellent device bending stability. Finally, f-OPD-based luminescent oxygen (O2) sensors were successfully fabricated consisting of a photoluminescent O2 sensing film, a light source, and an f-OPD. The O2 sensors based on d-PEIE-based f-OPDs showed the highest photocurrent and O2 sensitivity in relation to the O2 concentration compared with O2 sensors based on f-OPDs with conventional ETL materials.
关键词： organic photodiodes,electron transport layer,Cs2CO3,polyethyleneimine ethoxylated
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Nanodot-Molecule Junctions: Assessing Intermolecular Interactions and Electron Transport at Microwave Frequencies
摘要： Here, we present the properties of molecular junctions fabricated on a large array of sub-10 nm single crystal Au nanodot electrodes, each junction being made of less than one hundred molecules. Thanks to this approach, we discuss some pending issues in molecular electronic : (i) the determination of inter-molecular interactions from the conductance histograms of molecular junctions, (ii) the demonstration of molecular electronic devices for high-frequency operation with a molecular diode working in the microwave regime up to 18 GHz.
关键词： Molecular electronics,interaction energy,scanning microwave microscope,microwave,electron transport,conducting-AFM
更新于2025-09-10 09:29:36
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Electron transport in ladder-shaped graphene cuts
摘要： We numerically investigate electrical conductance of ladder-shaped graphene cuts (LGCs). Our calculations are performed by using non-equilibrium Green’s function method, in the nearest neighbor tight binding approximation. Our findings reveal strong sensitivity of electron transport through side rails of LGC to number, length and width of its rungs. Adding more rungs to ladder destroys the transport process in side rails. By lengthening the rungs transmission increases and finally tends to a constant value. Rungs widening has also destructive effect on electron transport via side rails. The results show that the transport properties of the LGC could be tuned via changing its structure, to discover transition from metal to insulator and vice versa. We also find that, lengthening of the ladder decreases transport along its side rails.
关键词： Electron transport,Ladder-shaped graphene cut,Non-equilibrium Green’s function
更新于2025-09-10 09:29:36
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Gallium Oxide || Low-field and high-field transport in β-Ga2O3
摘要： β-Ga2O3 has recently emerged as a novel wide-bandgap semiconductor with immense potential for applications in power electronics and optoelectronics. Experimental advancements in the past 5 years have been significant toward realizing commercial β-Ga2O3 devices in the near future [1–7]. Matured crystal growth and processing techniques make the material further promising [8–10]. In terms of power electronic applications, MOSFETs based on this material have been demonstrated that could withstand record high voltages [11, 12]. The accuracy of n-type doping and the difficulty of p-type doping make electrons the primary charge carriers in β-Ga2O3. Although β-Ga2O3 has lower electron mobility compared to other wide-bandgap semiconductors, it is found to have a superior Baliga’s figure of merit that jointly accounts for on-state resistance and breakdown voltage [4]. So it is important to investigate in rigor the fundamentals behind β-Ga2O3 material properties that could be beneficial to gain an understanding on the causes that control mobility and breakdown voltage. There are theoretical reports on fundamental materials aspects including electronic structure [13] and optical properties [14], lattice dynamical and dielectric properties [15], and thermal properties [16, 17] as well. The primary physics behind both mobility (and hence the device on resistance) and breakdown voltage lies in the electron transport phenomenon. There have been a few experimental reports that try to characterize the electron transport and scattering mechanisms in β-Ga2O3 with Hall measurements being reported a few times to predict temperature dependence and also crystal orientation dependence of the electron mobility [18, 19]. On the other hand, we are making a systemic study on the theoretical understanding of electron transport in β-Ga2O3 starting from the first principles [20–22]. The main idea is to follow a bottom-up approach in order to develop an understanding of the near-equilibrium and far-from-equilibrium electron dynamics in β-Ga2O3. This is unique compared to conventional semiconductors in a way that β-Ga2O3 has a low-symmetry crystal structure and a fairly large primitive unit cell that gives rise to many phonon modes. On several occasions, the traditional notions of electron transport that are applicable to Si and GaAs actually do not quite hold well in the case of β-Ga2O3. In this chapter, we attempt to provide a comprehensive picture of electron transport in β-Ga2O3 under low and moderately high electric fields based on our work in the recent years.
关键词： electron-phonon interaction,β-Ga2O3,electron mobility,power electronics,optoelectronics,electron transport,velocity-field curves,wide-bandgap semiconductor
更新于2025-09-09 09:28:46
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Characterization of electron charging and transport properties of Si-QDs with phosphorus doped Ge core
摘要： We formed high-density Si quantum dots (Si-QDs) with undoped and P-doped Ge cores on thermally-grown SiO2 by controlling low pressure chemical vapor depositions of Si and Ge. Doping into the Ge core was carried out during selective-growth of Ge on pre-grown Si-QDs. From hard x-ray photoelectron spectroscopy measurements, we con?rmed phosphorus incorporation into the Ge core, where phosphorus donor concentration in the Ge core was roughly estimated to be ～0.09 at%. When the surfaces of Si-QDs with undoped and P-doped Ge cores were scanned with an Rh-coated tip biased at 0 V, the surface potential of Si-QDs with P-doped Ge cores were increased by ～30 mV, while that of Si-QDs with undoped Ge cores remained unchanged. These results indicate that an electron was extracted from the conduction band of the Ge core due to a phosphorus donor. In the current images measured with the Rh-coated tip, the current level of Si-QDs with P-doped Ge cores on n-Si(100) substrates was higher than that of Si-QDs with undoped Ge cores. This result indicates that phosphorus donor can contribute to an increase in the electron injection rate from the Si-substrate.
关键词： Ge core,Si quantum dot,surface potential,doping,electron transport
更新于2025-09-09 09:28:46
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Synthesis of Naphthalenediimide-Based Co-Polymers for <i>n</i> -Channel Organic Field-Effect Transistors
摘要： Two copolymers containing alternating electron-donating and electron-accepting units, based on naphthalene diimide and bithiophene vinylene bithiophene with different pendant groups, i.e., C24 (P(NDI-T2VT2)-24) and C28 (P(NDI-T2VT2)-28) are synthesized via Stille-coupling polymerization reaction to study the effect of length of the alkyl side chain on the performance of n-type organic ?eld-effect transistors (OFETs). The thermal stability, optical absorption, thin-?lm crystallinity, and electronic properties of the OFETs with the copolymers are investigated. Both polymers showed reliable n-type transistor characteristics with electron mobility of 0.015 cm2/Vs (C24) and 0.019 cm2/Vs (C28) with a standard deviation of 0.01 from 36 devices. Furthermore, (P(NDI-T2VT2))-C28 OFETs showed slightly better device mobility than C24 because of their better solubility and crystallinity. Mobilities up to 0.019 cm2/Vs are recorded for (P(NDI-T2VT2))-C28 are analyzed.
关键词： Extended π-Conjugation,Bithiophene Vinylene Bithiophene,Electron Transport,Naphthalene Diimide (NDI)
更新于2025-09-09 09:28:46
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Performance analysis of a substrate-engineered monolayer MoS2 field-effect transistor
摘要： We investigate the impact of different substrates on the performance of a monolayer MoS2 field-effect transistor (FET) by calculating the interface charge density between the MoS2 layer and the substrate using first-principle calculations based on density functional theory to provide details about the overlap of electron orbitals at the interface. The electrical characteristics of the monolayer MoS2 FET are determined by using the extracted interface charge density in numerical simulations. The electron transport behavior of the monolayer MoS2 FET is modeled using the nonequilibrium Green’s function with mode space (NEGF_MS) approach. We study and compare the performance of monolayer MoS2 FETs on different substrates, viz. SiO2, HfSiO4, Si3N4, HfO2, and h-BN. The results reveal that the monolayer MoS2 FET on the h-BN/Si substrate exhibits an on-current of 548 μA/μm and a subthreshold swing of 65 mV/dec.
关键词： Carrier fluctuations,Electron transport,Charge density,NEGF_MS,Monolayer MoS2 FET
更新于2025-09-09 09:28:46
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Extremely Light Carrier‐Effective Mass in a Distorted Simple Metal Oxide
摘要： Exotic electron transport properties such as quasi 1D conductivity are useful to realize advanced electronic devices showing unique properties. Anisotropic electron transport properties are often found in complex metal oxides due to their complicated crystal structures. Although simple metal oxides with distorted crystal structures could also be expected to show anisotropic electron transport properties, it is rarely studied most likely due to the lack of their high-quality epitaxial films. Here anisotropic electron transport properties, showing “fast electron transport path,” in a simple distorted metal oxide, NbO2, is reported. High-quality NbO2 epitaxial films with different crystallographic orientations on (0001) and (11102) α-Al2O3 single crystal substrates are fabricated, and the electron transport properties at room temperature are measured. Both the resistivity and absolute value of the thermopower along the [112] NbO2 is pretty small as compared with other directions. Experimentally obtained electron carrier effective mass in the [112] direction is surprisingly small, only 0.051 me, which is similar to that of high-mobility GaAs. Since simple metal oxides have several advantages against complex oxides in view of easy fabrication, the present results will be beneficial for realizing advanced electronic devices using simple metal oxides.
关键词： distorted simple metal oxide,NbO2,epitaxial films,carrier effective mass,anisotropic electron transport
更新于2025-09-09 09:28:46
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Particle-in-cell simulation of ultrafast hot-carrier transport in Fe/Au heterostructures
摘要： We present a theoretical approach for spin-polarized hot-electron transport, as it occurs after excitation by ultrafast optical pulses in heterostructures formed by ferromagnetic and normal metals. We formulate a spin-dependent particle-in-cell model that solves the Boltzmann equation for excited electrons. It includes lifetimes and transmission coefficients as parameters, which can be taken from ab initio calculations or experiment, and can be easily extended to multilayer systems. This approach is capable of describing electron transport in the ballistic, superdiffusive, and diffusive regime including secondary-carrier generation. We apply the model to optically excited carriers in Fe/Au bilayers and Fe/Au/Fe spin-valve structures and analyze theoretically the hot-electron transport dynamics probed in recent experiments on spin valves. We find contributions to the demagnetization dynamics induced in Fe/Au/Fe trilayers regardless of the parallel or antiparallel magnetic alignment of the Fe layers.
关键词： ferromagnetic and normal metals,ultrafast optical pulses,Fe/Au/Fe spin-valve structures,Fe/Au bilayers,Boltzmann equation,spin-polarized hot-electron transport
更新于2025-09-04 15:30:14