- 标题
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- 实验方案
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35.3: Self-formed nano-scale metal-oxide contact interlayer for amorphous silicon tin oxide TFTs
摘要： The formation of metal oxide interlayer is induced by pre-annealing process in the amorphous Silicon-Tin-Oxide thin film transistors (a-STO TFTs) with Mo source/drain electrodes. Cross-sectional high-resolution transmission electron microscopy image confirmed the formation of ~8nm MoOx interlayer. The introduction of MoOx interlayer between Mo electrodes and a-STO improved the electron injection in a-STO TFT. Mo adjacent to the a-STO semiconductor gets oxygen atoms from the oxygen-rich surface of a-STO film to form MoOx interlayer. The self-formed MoOx interlayer acting as an efficient interface modification layer could conduce to the stepwise internal transport barrier formation while blocking Mo atoms diffuse into a-STO layer, which would contribute to the formation of ohmic contact between Mo and a-STO film.
关键词： self-formed interlayer,amorphous Silicon-Tin-Oxide,work function,Thin film transistors,ohmic contact
更新于2025-09-19 17:15:36
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Epitaxial growth and determination of the band alignment for NixMg1-xO/MgO interface by laser molecular beam epitaxy
摘要： By laser molecular beam epitaxy, single crystalline NixMg1-xO films have been successfully synthesized on MgO(100) surface. The in situ reflection high-energy electron diffraction patterns show that the induced O2 background gas with at least 1.0 × 10?3 Pa is necessary to the epitaxial growth of NixMg1-xO films. The X-ray diffraction patterns reveal the single-phase growth along (200) direction. The energy band alignment at the interface is investigated by employing in situ X-ray photoelectron spectroscopy. The valence band offsets are determined to be from 1.47 eV to 1.50 eV with the decrease of Ni content (0.39 / 0.35). Furthermore, the work function is evaluated by using in situ ultraviolet photoemission spectroscopy, indicating the values from 4.33 eV to 4.64 eV. This study provides a promising guidance for the solar-blind device design and fabrication.
关键词： Work function,X-ray photoelectron spectroscopy,Band alignment,Ultraviolet photoemission spectroscopy,Laser molecular beam epitaxy
更新于2025-09-19 17:13:59
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Functionalization of fullerene by polyethylene glycol toward promoted electron transport in inverted polymer solar cells
摘要： A novel polyethylene glycol-functionalized fullerene derivative (C60-PEGA) was synthesized by a facile one-step nucleophilic addition reaction. C60-PEGA possessed good solubility in methanol and was estimated as C60-( C8H18N)13H13O with average PEG moiety of 13 by 1H NMR, FT-IR and X-ray photoelectron spectroscopy (XPS) spectra. C60-PEGA was applied as an ETL to construct inverted bulk heterojunction polymer solar cells (inverted BHJ-PSCs) based on photoactive layers of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]: [6,6]-phenyl-C71-butyric acid methyl ester (PTB7-Th: PC71BM), which achieve the best PCE of 9.25%, surpassing that of reference device based on the ZnO ETL (8.61%). The higher ETL performance of C60-PEGA ETL in BHJ-iPSC device relative to that of the ZnO ETL was attributed to the increase of electron mobility and effective electron transport from the active layer to the ITO cathode because that the reduced work function (WF) of ITO via the modification of C60-PEGA leads to the increase of short-circuit current density (Jsc) and consequent PCE.
关键词： polyethylene glycol (PEG),electron transport layers (ETLs),inverted polymer solar cells,work function,fullerene derivative
更新于2025-09-19 17:13:59
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A New Fabrication Method for Serpentine-Folded Waveguide Slow Wave Structure at W-Band
摘要： Thermionic energy converter (TEC) is a heat engine that generates electricity directly using heat as its source of energy and electron as its working fluid. Despite having a huge potential as an efficient direct energy conversion device, the progress in vacuum-based thermionic energy converter development has always been hindered by the space charge problem and the unavailability of materials with low work function. It is only recently that researchers have started to look back into this technology as recent advances in manufacturing technology techniques have made it possible to solve these problems, making TECs a viable option in replacing current energy production systems. The focus of this paper is to review the challenges of producing efficient and practical TECs, along with recent findings and developments in mitigating these challenges. Furthermore, this paper looked into potential applications of TECs, based on recent works and technologies, and found that, with certain improvements, it can be applied in many sectors.
关键词： nanowires,work function,thermionic energy conversion (TEC),space charge,Energy conversion efficiency
更新于2025-09-19 17:13:59
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Numerical simulation of charge transport layer free perovskite solar cell using metal work function shifted contacts
摘要： Perovskite solar cells (PSCs) are one of the fastest emerging photovoltaic (PV) technology at the research level. To achieve higher conversion efficiencies from PSCs, a perovskite absorber layer is stacked between two charge transport layers (CTLs) such as electron and hole transport layers. However, fabrication of defect-free multi-layered PSC is a challenging task, and the presence of CTL and their corresponding interfaces with perovskite enhances the recombination, hysteresis and led to poor stability. Here, in this work, CTL free (i.e., electron and hole transport layer free) PSC is simulated using metal work function shifted contacts. The device presented in this work is free from transport layers and the collection process is with the help of an electric field across the perovskite layer. The electric field is created by using two metals of different work function, i.e., 4.35eV and 5.25eV (can be realized using self-assembled monolayers technique) used as cathode and anode respectively. Simulated CTL free PSC exhibits JSC=17.8 mA.cm-2, VOC=712 mV, FF=68.5% and PCE=8.7% with 250 nm thick perovskite absorber layer having bulk defect density of 2.5x1013 cm-3. Further, a comprehensive study is done in terms of front electrode work function (FEW), front electrode transparency, perovskite thickness and bulk defect density to understand the impact of these parameters on the performance of the device. To understand the behavior of the device, the energy band diagram profile is examined. Reported results show that higher metal work function difference between front and back electrode, higher transparency, and thick perovskite layer with low defect density results in better PV effect in CTL free PSC. Optimized CTL free PSC device delivers JSC=19.9 mA.cm-2, VOC=726 mV, FF=66.8% and PCE=9.7%. The design simulated in this work opens up a new window for next-generation interface defect and hysteresis-free PSC.
关键词： simulation,absorption,SCAPS-1D.,charge transport layer,metal work function,Perovskite solar cell,transparency
更新于2025-09-19 17:13:59
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Low work function Ca doped graphene as a transparent cathode for organic opto-electronics and OLEDs
摘要： Graphene is an excellent candidate for a transparent electrode since it has high lateral conductivity and optical transparency, but due to its high work function, between 4.5 - 5eV, it can serve as a good transparent anode but poor transparent cathode due to a barrier for electrons injection. Reducing graphene’s work function is thus essential to make it an ideal transparent cathode as well. Naturally, n-type doping of graphene increases its Fermi level and thus reduces the work function. Among many choices of n-type dopants alkaline element can be good candidate, here we present a study of calcium (Ca) n-doped graphene to be serve as a transparent cathode. Several measurements were carried out on Ca doped graphene and compared them with pristine graphene as a reference, such as: Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) Field effect transistor (FET), transparent electron microscopy (TEM), and photoemission spectroscopy. Our results show that doping graphene with 1nm of evaporated Ca on the surface reduces its work function by nearly 1eV. We further performed current-voltage characteristics of graphene/Alq3/Ag structures having undoped and doped graphene cathodes. The structures with doped graphene showed an increase of two orders of magnitude in current under the same applied bias due to the contacts barrier reduction. The results confirm the effectiveness of Ca-doped graphene for reducing the barrier for electron injection from graphene to next adjacent organic layer. It demonstrates the feasibility of Ca doped graphene to serve as a transparent cathode in organic devices in general and in OLEDs in particular.
关键词： OLEDs,organic opto-electronics,Ca doping,graphene,transparent cathode,work function
更新于2025-09-19 17:13:59
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Built-in voltage enhanced by in-situ electrochemical polymerized undoped conjugated hole-transporting modifier in organic solar cells
摘要： Herein, a new electropolymerized (EP) film named poly-triphenylcarbazole fluoranthene (p-TPCF) has been in-situ synthesized by electrochemical cyclic voltammetry method, and applied to tune the work-function (WF) of the PEDOT:PSS hole-transporting layer (HTL) in organic solar cells (OSCs). Multi techniques, including Kelvin probe force microscopy (KPFM), light intensity dependent solar cell characterization, Mott-Schottky analysis, transient photovoltage (TPV) and transient photocurrent (TPC) measurements, have been explored to provide insights into the mechanism. Benefiting from deeper work-function (WF), larger built-in voltage (Vbi), decreased recombination, longer carrier lifetime, the devices with EP film exhibited superior device performance with simultaneously enhanced Voc, Jsc and FF.
关键词： PEDOT:PSS,built-in voltage,work-function tuning,organic solar cells,carrier lifetime,electropolymerized film,charge recombination
更新于2025-09-19 17:13:59
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Excimer laser annealing method for achieving low electrical resistivity and high work function in transparent conductive amorphous In2O3:Zn films on a polyethylene terephthalate substrate
摘要： We have developed an excimer laser annealing method to achieve low electrical resistivity (ρ) and a high work function in amorphous In2O3:Zn (IZO) films on polyethylene terephthalate (PET) substrates. The effect of excimer laser irradiation of the films on crack formation, electrical properties (ρ, carrier concentration, and Hall mobility), and work function were investigated. KrF excimer laser irradiation produced cracks in the surface of the IZO films on PET as a result of thermal expansion of the PET substrate. By inserting an amorphous SiO2 layer as a heat barrier between the IZO layer and PET substrate, crack formation was prevented. Moreover, it was found that the work function of IZO film could be controlled by the laser fluence and repetition rate. Irradiation of a 150-nm-thick amorphous IZO film on a SiO2-coated PET substrate achieved a low ρ of 3.55 × 10?4 Ω cm and a high work function of 5.4 eV due to the reduction of oxygen and carbon while maintaining a flat surface.
关键词： Excimer laser annealing,Work function control,Buffer layer,Transparent conducting oxide
更新于2025-09-19 17:13:59
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Enhanced Emission of Deep Ultraviolet Light-Emitting Diodes Through Using Work Function Tunable Cu Nanowires as Top Transparent Electrode
摘要： Deep ultraviolet light-emitting diodes (DUV LEDs) (< 280 nm) have been important light sources for broad applications in, e.g., sterilization, purification, high-density storage and etc. However, the lack of excellent transparent electrodes in DUV region remains a challenging issue. Here, we demonstrate an architectural engineering scheme to flexibly tune the work function of Cu@shell nanowires (NWs) as top transparent electrodes in DUV LEDs. By fast encapsulation of shell metals on Cu NWs and shift of electron binding energy, the electronic work function could be widely tailored down to 4.37 eV and up to 5.73 eV. It is revealed that the high work function of Cu@Ni and Cu@Pt NWs could overcome the interfacial barrier to p-AlGaN and achieve direct ohmic contact with high transparency (91%) in 200 ~ 400 nm. Completely transparent DUV LED chips are fabricated and successfully lighted with sharp top emission (wall-plug efficiency reaches 3 %) under a turn-on voltage of 6.4 V. This architectural strategy is of importance in providing highly transparent ohmic electrodes for optoelectronic devices in broad wavelength regions.
关键词： copper nanowires,transparent electrodes,light-emitting diodes,Deep ultraviolet,work function
更新于2025-09-19 17:13:59
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Plasmonic Pt Superstructures with Boosted Near‐Infrared Absorption and Photothermal Conversion Efficiency in the Second Biowindow for Cancer Therapy
摘要： Defects are commonly found in two-dimensional (2D) transition-metal dichalcogenide (TMD) materials. Such defects usually dictate the optical and electrical properties of TMDs. It is thus important to develop techniques to characterize the defects directly with good spatial resolution, specificity, and throughput. Herein, we demonstrate that Kelvin probe force microscopy (KPFM) is a versatile technique for this task. It is able to unveil defect heterogeneity of 2D materials with a spatial resolution of 10 nm and energy sensitivity better than 10 meV. KPFM mappings of monolayer WS2 exhibit interesting work function variances that are associated with defects distribution. This finding is verified by aberration-corrected scanning transmission electron microscopy and density functional theory calculations. In particular, a strong correlation among the work function, electrical and optical responses to the defects is revealed. Our findings demonstrate the potential of KPFM as an effective tool for exploring the intrinsic defects in TMDs.
关键词： transition-metal dichalcogenides,density functional theory,defects,Kelvin probe force microscopy,scanning transmission electron microscopy,work function,two-dimensional materials
更新于2025-09-19 17:13:59