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- 2019
- low-temperature electronics
- junction field-effect transistors
- differential operational amplifier
- LTspice environment
- differential stage
- common-mode rejection ratio
- class AB operation
- optimization of analog electronic circuit
- operational amplifier
- LTspice environment
- Electronic Science and Technology
- Don State Technical University
- Southern Federal University
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Low-temperature Synthesized Nba??doped TiO <sub/>2</sub> Electron Transport Layer enabling High-efficiency Perovskite Solar Cells by Band Alignment Tuning
摘要： An Nb-doped TiO2 (Nb-TiO2) film comprising a double structure stacked with a bottom compact layer and top mesoporous layers was synthesized by treating a Ti precursor-coated substrate using a one-step low-temperature steam-annealing (SA) method. SA-based Nb-TiO2 films possess high crystallinity and conductivity, and that allows better control over the conduction band (CB) of the TiO2 for electron transport layer (ETL) of the perovskite solar cells (PSCs) by the Nb doping level. Optimization of power conversion efficiency (PCE) for the Nb-TiO2 based ETL was combined with CB level tuning of the mixed-halide perovskite by changing the Br/I ratio. This band offset management enabled to establish the most suitable energy levels between ETL and perovskites. This method was applied to reduce the bandgap of perovskite to enhance photocurrent density while maintaining a high open-circuit voltage. As a result, the optimal combination of 5 mol% Nb-TiO2 ETL and 10 mol%-Br in the mixed-halide perovskite exhibited high photovoltaic performance for low-temperature device fabrication, achieving a high yield PCE of 21.3%.
关键词： low-temperature process,solvent-free hydrothermal synthesis,electron transport layer,steam-annealing method,Perovskite solar cell,niobium-doped TiO2
更新于2025-09-19 17:13:59
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Evidence of Low Temperature Joints in Silver Nanowire Based Transparent Conducting Layers for Solar cells
摘要： The primary stage of joint formation of silver nanowires (AgNWs) at 60 °C is investigated using rotary scanning transmission electron microscopy (STEM with tomographic reconstruction images), and super large-scale molecular dynamic (MD) simulation (2×106 atoms). This study proves to establish that silver nanowires do not require the conventional high temperature post treatment process at 200 °C to form fused contacts at the intersections. In fact, a low temperature annealing at 60 °C facilitates formation of highly conductive networks. The connection between the nanowires is made through a stage called thinning, shown in this report for the first time, which occurs before broadening of the nanowires and is caused due to simultaneous effects of loads from the top nanowires and the heating, as confirmed by STEM and MD result. The outcomes of our investigation significantly promote the application of AgNWs as a transparent conductive layer for solar cells with requirement of low temperature processing such as Kasterite, Perovskite and Organic solar cells.
关键词： Low temperature process,Scanning transmission electron microscopy,Molecular dynamic simulation,Junction resistivity,Transparent conductive layer,Silver nanowire
更新于2025-09-19 17:13:59
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Low-temperature chemical vapor deposition growth of graphene films enabled by ultrathin alloy catalysts
摘要： This report introduces a method for fabricating graphene at low temperatures via chemical vapor deposition enabled by ultrathin (～1 nm) nickel-gold (Ni-Au) catalysts. The unique combination of high carbon (C) solubility Ni, low C solubility Au, and an ultrathin layer of a catalyst demonstrates the effectiveness to produce graphene at 450 °C with the layer number independent of growth duration. In contrast to grain-boundary defined catalyst morphology found in thicker (>20 nm) metal catalysts, the ultrathin catalyst morphology leads to the formation of nanoscale metal “islands” during the growth process, which results in curved graphene covering the catalyst. To test the effect of preactivation of the ultrathin catalyst for the formation of graphene, a preanneal process of the catalyst followed by the introduction of a carbon precursor was also investigated. The preanneal process resulted in the formation of carbon nanotubes (CNTs) in lieu of graphene, displaying the impact of the catalytic surface treatment in relation to the produced materials. The results and discussion presented here detail a low-temperature nanoscale manufacturing process that allows for the production of either graphene or CNTs on an ultrathin catalyst.
关键词： graphene,low-temperature growth,nickel-gold catalysts,chemical vapor deposition,ultrathin alloy catalysts
更新于2025-09-19 17:13:59
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Anharmonic Effects in Single-Walled Carbon Nanotubes Analyzed through Low-Temperature Raman Imaging
摘要： The high thermal conductivity of single-walled carbon nanotubes (SWCNT) has gained much attention for their applications in potential thermal devices. Here, we investigate anharmonic effects, originated from phonon interactions, of SWCNT bundles by temperature dependent Raman imaging using our home-built mini cryostat system. The cryostat system is small enough to be mounted on a piezo scanner that suppresses thermal drift, enabling Raman imaging at different temperatures. We obtained Raman spectral images of several SWCNT bundles with a spatial resolution of a few hundred nanometers at different temperatures. We found that different bundles show different temperature dependences of Raman peak intensity, shift, and width. The temperature dependence was further elucidated by considering the sample topography observed by atomic force microscopy, where bundle effects seem to play an important role to influence the anharmonicity. The temperature-dependent Raman analysis based on spatially resolved imaging will be a powerful tool to investigate anharmonic effects of advanced carbon nanomaterials as well as to realize in-situ visualization of thermal properties for future thermal devices.
关键词： single-walled carbon nanotubes,anharmonic effects,low-temperature,Raman imaging,thermal properties
更新于2025-09-19 17:13:59
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Ozone-mediated Controllable Hydrolysis for High Quality Amorphous NbO <sub/>x</sub> Electron Transport Layer in Efficient Perovskite Solar Cells
摘要： Amorphous NbOx electron transport layer (ETL) shows great potential for boosting the power conversion efficiency (PCE) of perovskite solar cells (PSCs) at low temperature (< 100 °C). To date, it is still a challenge to simultaneously control the hydrolysis of NbOx precursor solution and reduce the impurities of NbOx ETLs during low-temperature solution processing under ambient conditions. Herein, for the first time, we report ozone (O3) as a strong ligand to stabilize Nb salt solution under ambient conditions. The above procedure not only provides the formation of a highly repeatable amorphous NbOx film by suppressing the hydrolysis of the solution but also reduces the OH content in the film, which decreases the defect intensity and improves the conductivity of the NbOx ETL. Thus, the formation of highly repeatable NbOx ETL-based PSCs are obtained; moreover, these PSCs have high PCE of 19.54% and 16.42% on rigid and flexible substrate, respectively, much higher than the devices based on ETLs from a solution without an O3 treatment.
关键词： NbOx,electron transport layer,perovskite solar cell,amorphous oxide semiconductors,low temperature
更新于2025-09-19 17:13:59
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Ultraviolet-ozone modification on TiO2 surface to promote both efficiency and stability of low-temperature planar perovskite solar cells
摘要： As a classical electron transport layer, the high crystallinity TiO2 has been widely used in perovskite solar cells (PSCs), however, its high-temperature preparation process elevates the fabrication cost and limits its application. Here, we report an ultraviolet-ozone assisted strategy to modify low-temperature TiO2 interface for PSCs. In addition to the more appropriate work function and reinforced built-in potential, the lattice strain of perovskite films crystallized on modified TiO2 has also been released in some degree. Ultrafast transient absorption technique is employed to provide an deep insight into the carrier dynamics, revealing that less non-radiative recombination exists in the modified device. Interestingly, transient surface photovoltage results demonstrate that ultraviolet-ozone modification can efficiently suppress the decomposition of perovskite films under light illumination. Taking advantage of these facts, this device exhibits better efficiency and remarkable stability. This demonstrated low-temperature strategy is a promising way for fabricating low-cost, efficient and stable perovskite device.
关键词： interface passivation,ultraviolet-ozone treatment,photocatalysis,low-temperature TiO2,perovskite solar cells
更新于2025-09-19 17:13:59
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[IEEE 2019 European Space Power Conference (ESPC) - Juan-les-Pins, France (2019.9.30-2019.10.4)] 2019 European Space Power Conference (ESPC) - Accurate Solar Cell Measurements at Low Temperatures using a Cryostat
摘要： Calibrated measurements of solar cells at low temperatures are of specific interest for various space missions, for example to Mars and Jupiter. In the past 15 years, several hundred triple-junction and component solar cells have been measured at the solar cell calibration laboratory at Fraunhofer ISE (CalLab PV Cells), mainly in the frame of the European Space Agency (ESA) programs ExoMars and JUICE. To allow for measurements at temperatures as low as 123 K a specially developed cryostat setup is being used. This paper summarizes the main challenges and findings in respect to measurement low procedures and calibration of solar cells under temperature conditions, including the mounting of the solar cells, control of the correct solar cell temperature, and definition of the correct illumination spectrum and intensity.
关键词： cryostat,low intensity low temperature,space solar cells,LILT,solar cell characterization
更新于2025-09-16 10:30:52
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Interlayer Engineering for Flexible Large-Area Planar Perovskite Solar Cells
摘要： Hybrid metal halide perovskite solar cells (PSCs) have consistently demonstrated high power conversion efficiency (PCE), although the best performing PSCs mostly employ high-temperature (500 oC) processed compact and mesoporous TiO2. Instead, low-temperature processed PSCs are desirable for implementation on flexible substrates and tandem solar cells. Here, we present a new method to achieve high efficiency flexible planar PSCs based on a low-temperature processed nonaqueous sol-gel route synthesized TiO2 and a guanidinium iodide (GuaI) salt passivation treatment of the perovskite film. We fabricate both rigid and flexible triple-cation perovskite (Cs0.05 (MA0.17FA0.83)0.95Pb(I0.85Br0.15)3, Eg ~1.58 eV) PSCs, achieving PCEs of 19.8% and 17.0% on glass and polyethylene naphtholate, (PEN) substrates respectively. At the same time, rigid and flexible high-bandgap double cation (FA0.85Cs0.15Pb(I0.7Br0.3)3, Eg ~1.72 eV) PSCs reached a PCE of 18.0 % and of 15.8%. Moreover, large area (1cm2) ~1.58 eV and ~1.72 eV-PSCs achieved PCEs of 18.2% and 16.7% PCE on glass substrates and of 16.2% and 13.9% on PEN substrates demonstrating the high uniformity of all the solar cell layers.
关键词： Solar Cells,Flexible,Guanidinium Iodide Passivation,Perovskite,Low Temperature TiO2
更新于2025-09-16 10:30:52
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Ultraviolet Nanosecond Laser Annealing for Low Temperature 3D-Sequential Integration Gate Stack
摘要： For the top tier in a 3D sequential integration, we propose a low temperature gate first approach in which an in-situ doped amorphous silicon layer is deposited at 475°C then subsequently converted into a polycrystalline film using ultraviolet nanosecond laser annealing. We demonstrate the ability to obtain a low resistance poly-Si gate for the top transistors within a thermal budget expected to preserve the bottom devices electrical performance.
关键词： Ultraviolet Nanosecond Laser Annealing,Polycrystalline Silicon,3D-Sequential Integration,Low Temperature Gate Stack
更新于2025-09-16 10:30:52
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Chemically doped hole transporting materials with low cross-linking temperature and high mobility for solution-processed green/red PHOLEDs
摘要： Recently, developing insoluble cross-linkable functional layers plays a vital role for solution-processed organic light emitting diodes (OLEDs). Here, two vinyl-based cross-linkable hole transporting materials V-TPAVTPD and V-TPAVCBP are designed and synthesized. Additionally, cationic photoinitiator 4-octyloxydiphenyliodonium hexafluoroantimonate (OPPI) is first introduced to chemically induce vinyl-based photo cross-linking process, aiming at lowering cross-linking temperature and enhancing hole mobility. As a result, cross-linking can occur at expressly low temperature of 120 °C with >95% solvent resistance. Moreover, hole mobility is markedly enhanced with the value higher than 10-3 cm2 V-1 s-1. When applying hole transporting layers (HTLs) to solution-processed green and red phosphorescent OLEDs, devices exhibit excellent properties. Particularly, the maximum current efficiency of 54.0 cd A?1 (green), 9.8 cd A?1 (red) and external quantum efficiency of 15.5% (green), 15.0% (red) are obtained when OPPI doped V-TPAVCBP serves as HTL. This low temperature feasible cross-linking process to prepare HTLs with preferable hole mobility promotes the development of OLEDs.
关键词： organic light emitting diode,low temperature,solution-processed,cross-linkable,4-octyloxydiphenyliodonium hexafluoroantimonate,hole transporting material
更新于2025-09-16 10:30:52