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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Work function of polarized boron 2D atomic crystal
摘要： We discuss the method to calculate the work function of polarized materials with first principles calculation. Then we take boron 2D atomic crystal as an example. We found that the Alkali metal adsorbates decrease the work function of the surface with adsorbates, while the work function of the other surface is unaffected, when the alkali metal atoms are absorbed on only one surface of the boron sheet. The reason is attributed to the polarization between the alkali metal atoms and the boron sheet.
关键词： work function,2D atomic crystal,boron
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Development of a Low-Work-Function Thermionic Cathode by Coating with LaB<inf>6</inf> and Carbide
摘要： A novel electron gun with lanthanum hexaboride (LaB6) thermionic cathodes with relatively low work functions is being developed by coating the metal surface with another material. When operated under thermionic emission mode, this tool provides both high brightness and high beam current simultaneously, has a long lifetime, and offers good stability during operation. Herein, we describe the basic design concept for a novel LaB6 cathode involving infiltration of a carbide solution. Moreover, we experimentally measured the thermionic-emission-mode work function of the rhenium surface modified with a LaB6 single-crystal powder and carbide solution.
关键词： work function,carbide solution,lanthanum hexaboride,thermionic emission
更新于2025-09-23 15:21:21
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Efficient and selective sensing of nitrogen containing gases by Si2BN nanosheets under pristine and pre-oxidized conditions
摘要： Motivated by the promise of two-dimensional nanostructures in the field of gas sensing, we have employed van der Waals corrected density functional theory calculations to study the structural, electronic and gas sensing propensities of recently designed Si2BN monolayer. Our rigorous simulations reveal that the representative members of nitrogen containing gases (NCGs) such as NO, NO2 and NH3 binds extremely strongly on pristine Si2BN monolayer. However a strong dissociative adsorption in case of NO and NO2 would poison the Si2BN and ultimately reversibility of the monolayer would be compromised. Exploring the sensing mechanism in more realistic pre-oxidized conditions, the binding characteristics of O2@Si2BN changed dramatically, resulting into much lower adsorption in associative manner for all NO, NO2 and NH3. A visible change in work function indicates the variation in conductivity of O2@Si2BN upon the exposure of incident gases. Sustainable values of binding energies would also ensure a quick recovery time that makes O2@Si2BN an efficient nano sensor for pollutants like NCGs.
关键词： Conductivity,Adsorption,Work function,Recovery time,Monolayer
更新于2025-09-23 15:21:21
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Hydroxymethyl Functionalized PEDOT-MeOH:PSS for Perovskite Solar Cells
摘要： Poly(hydroxymethylated-3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT-MeOH:PSS) conducting polymers are synthesized and incorporated in inverted structured perovskite solar cells (PVSCs) as hole transport materials. The highest occupied molecular orbital of PEDOT-MeOH is lowered by adding a hydroxymethyl (-MeOH) functional group to ethylenedioxythiophene (EDOT), and thus the work function of PEDOT-MeOH:PSS is increased. Additionally, hydrogen bonding can be formed among EDOT-MeOH monomers and between EDOT-MeOH monomers and sulfate groups on PSS, which promote PEDOT-MeOH chain growth and enhance PSS doping. The electronic, microstructural, and surface morphological properties of PEDOT-MeOH:PSS are modified by changing the amount of PSS and ferric oxidizing agent used in the polymerization and by adding ethylene glycol in the post-synthesis treatment. The PVSCs based on ethylene glycol treated PEDOT-MeOH:PSS overperform the PVSCs based on commercial PEDOT:PSS because of the better energetic alignment and the enhancement of PEDOT-MeOH:PSS electrical conductivity. This work opens the way to develop new hole transport materials for highly efficient inverted PVSCs.
关键词： hole transport material,perovskite,solar cell,electrical conductivity,work function
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - On the impact of the metal work function on the recombination in passivating contacts using quasi-steady-state photoluminescence
摘要： Understanding the impact of metal contacts on the recombination within a passivated silicon wafer is crucial for the optimization of various photovoltaic devices such as passivating-contact-based solar cells. To investigate the effect of the metal work function, a selection of metals is applied to aluminum-oxide-passivated n-type crystalline silicon wafers. The saturation current density of the metalized contact (J0m) is determined using the quasi-steady-state photoluminescence method and used as a figure of merit to quantify the effect. We find that J0m increases with the metal work function and that this effect is modulated with the passivation layer thickness. It is more pronounced for thinner passivation layers, which can be attributed to a significant change in the populations of electrons and holes near the silicon surface induced by the metal. Meanwhile thicker layers prevent the charge transfer between the silicon and metal more efficiently leading to insignificant changes in J0m. Based on these findings, we suggest a suitable metal work function range to optimize contact recombination in silicon-based solar cells.
关键词： passivating contacts,surface recombination,saturation current density,quasi-steady-state photoluminescence,work function,Effective lifetime,silicon solar cells
更新于2025-09-23 15:21:01
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Tailoring PEDOT:PSS polymer electrode for solution-processed inverted organic solar cells
摘要： The review of this paper was arranged by A. Zaslavsky. Conductivity and work function of the conductive polymer, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), has been investigated for a top electrode of the solution-processed organic solar cells (OPV). It has been found that both conductivity and work function could be changed by adjusting the mixing ratio of different commercial grade PEDOT:PSS such as PH 1000 and AI 4083. A 2:1 vol ratio of PH 1000 and AI 4083 mixture provided the conductivity of 443 S/cm (corresponding sheet resistance (Rsh) of 260 Ω/sq) and the work function of 5.09 eV. Therefore, this PEDOT:PSS mixture may work as both a hole transport layer (HTL) and anode electrode of the OPV. For verifying, all-solution-processed bulk heterojunction (BHJ) inverted OPVs were fabricated using developed PEDOT:PSS conductive polymers as both HTL and anode top electrode. Under the AM1.5G spectrum calibrated 100 mW/cm2 illumination, fabricated all-solution-processed OPV provides a best photo-conversion efficiency (PCE) of 2.04% accounted from an open circuit voltage (Voc) of 576 mV, a short circuit current (Jsc) of 6.91 mA/cm2, and a fill factor (FF) of 51.2%. In addition, the final OPV exhibits semitransparency due to no metal electrode on top and transparency of the conductive polymer.
关键词： Organic photovoltaics,Semitransparency,All-solution-process,Work function,Conductivity,PEDOT:PSS
更新于2025-09-23 15:21:01
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Simulation of Silicon Heterojunction Solar Cells for High Efficiency with Lithium Fluoride Electron Carrier Selective Layer
摘要： In this work, to ameliorate the quantum e?ciency (QE), we made a valuable development by using wide band gap material, such as lithium ?uoride (LiFx), as an emitter that also helped us to achieve outstanding e?ciency with silicon heterojunction (SHJ) solar cells. Lithium ?uoride holds a capacity to achieve signi?cant power conversion e?ciency because of its dramatic improvement in electron extraction and injection, which was investigated using the AFORS-HET simulation. We used AFORS-HET to assess the restriction of numerous parameters which also provided an appropriate way to determine the role of diverse parameters in silicon solar cells. We manifested and preferred lithium ?uoride as an interfacial layer to diminish the series resistance as well as shunt leakage and it was also bene?cial for the optical properties of a cell. Due to the wide band gap and better surface passivation, the LiFx encouraged us to utilize it as the interfacial as well as the emitter layer. In addition, we used the built-in electric and band o?set to explore the consequence of work function in the LiFx as a carrier selective contact layer. We were able to achieve a maximum power conversion e?ciency (PEC) of 23.74%, ?ll factor (FF) of 82.12%, Jsc of 38.73 mA cm?2, and Voc of 741 mV by optimizing the work function and thickness of LiFx layer.
关键词： electric ?eld,silicon heterojunction solar cell,lithium ?uoride,electron selectivity contact layer,work function
更新于2025-09-23 15:21:01
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[SpringerBriefs in Applied Sciences and Technology] Air-Stable Inverted Organic Light-Emitting Diodes || Carrier Injection Mechanism
摘要： Both hole and electron injection layers are commonly used in recent OLEDs to reduce the injection barrier between electrodes and organic layers. This injection barrier originates from the energy difference between the work function (WF) of the electrode and the energy level of the organic layer. For instance, the hole injection barrier is defined as the energy difference between the Fermi level of the anode and the highest occupied molecular orbital (HOMO) level of the organic layer on the anode, as shown in Fig. 4.1a. Thus, an ideal hole injection material is the material that can make the surface WF of the anode larger (Fig. 4.1b). On the other hand, an ideal electron injection material is the material that can make the surface WF of the cathode smaller (Fig. 4.1c).
关键词： energy level alignment,OLEDs,electron injection,hole injection,work function
更新于2025-09-23 15:21:01
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A passivation mechanism exploiting surface dipoles affords high-performance perovskite solar cells
摘要： The employment of 2D perovskites is a promising approach to tackle the stability and voltage issues inherent in perovskite solar cells. It remains unclear however whether other perovskites with different dimensionalities have the same effect on efficiency and stability. Here, we report the use of quasi-3D azetidinium lead iodide (AzPbI3) as a secondary layer on top of the primary 3D perovskite film that results in significant improvements in the photovoltaic parameters. Remarkably, utilization of AzPbI3 leads to a new passivation mechanism due to the presence of surface dipoles resulting in a power conversion efficiency (PCE) of 22.4 %. The open-circuit voltage obtained is as high as 1.18 V, which is among the highest reported to date for single junction perovskite solar cells, corresponding to a voltage deficit of 0.37 V for a bandgap of 1.55 eV.
关键词： Perovskites,dipoles,work function,surface passivation,solar cells
更新于2025-09-23 15:21:01
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Boosted efficiency of conductive metal oxide-free pervoskite solar cells using poly[3-(4-methylamincarboxylbutyl)thiophene] buffer layers
摘要： Owing to low work functions of transparent anodes and poor contact issues at interfaces, the p-i-n conductive metal oxide (CMO)-free perovskite solar cells (PVSCs) commonly suffered from a limited power conversion efficiency. Herein, we reported an efficient CMO-free PVSC using poly[3-(4-methylamincarboxylbutyl)thiophene] (P3CT-N) modified poly(3,4-ethylenedioxylenethiophene):poly(styrenesulfonate) (PEDOT:PSS) anodes. The contact angle between PEDOT:PSS anodes and P3CT-N buffer layers tended to be 0o for an intimate contact. Meanwhile, the work function of the PEDOT:PSS anodes coated with P3CT-N is as high as -5.11 eV, which substantially accounted for the raised ability of hole transport. All the parameters (i.e., open-circuit voltage, short-circuit current density and fill factor) were improved simultaneously. As a result, the efficiency of the CMO-free solar cells was significantly improved from 4.63% to 13.13%. Our results indicate that P3CT-N is suitable to the highly conductive but hydrophobic PEDOT:PSS anodes for making high-efficiency CMO-free PVSCs.
关键词： work function,CMO-free,perovskite solar cells,PEDOT:PSS,P3CT-N
更新于2025-09-23 15:21:01