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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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Effect of tantalum doping on SnO <sub/>2</sub> electron transport layer via low temperature process for perovskite solar cells
摘要： The electron transport layer (ETL) plays an important role in determining the device performance of perovskite solar cells (PSCs). Recently, SnO2 has been used extensively as an ETL due to its many outstanding optoelectronic properties. Herein, we develop Ta doped SnO2 (Ta-SnO2) as an ETL grown by chemical bath deposition, allowing the fabrication of low-temperature PSCs. In contrast to pristine SnO2, the I-V curve and transmittance spectra show a signi?cant conductivity improvement of Ta-SnO2 without declining the light transmittance property. Meanwhile, Ta-doping could accelerate the electron transfer and decrease the recombination probability at the SnO2/perovskite interface, as well as passivate the electron traps, leading to the improvement in the PSC performance. Through a series of optimization methods, the champion device shows a power conversion ef?ciency of 20.80%, with an open-circuit voltage of 1.161 V, a short-circuit current density of 22.79 mA/cm2, and a ?ll factor of 0.786. SnO2 with a suitable Ta content is a promising candidate as an ETL for fabricating high-ef?ciency PSCs via the low-temperature process.
关键词： perovskite solar cells,Ta doping,SnO2,electron transport layer,low-temperature process
更新于2025-09-16 10:30:52
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P3HT-based visible-light organic photodetectors using PEI/PAA multilayers as a p-type buffer layer
摘要： A low leakage current is critical for achieving organic photodetectors (OPDs) with high detectivity. The insertion of buffer layers is an effective approach for reducing the reverse-biased leakage current. In this study, polyelectrolyte multilayers comprising polyethyleneimine (PEI) and polyacrylic acid (PAA) were introduced by a spin-assisted layer-by-layer technique into an OPD as a p-type buffer layer. Although PEI/PAA multilayers are insulators, when used as a buffer layer in our device, they suppressed the leakage current and also provided a high photocurrent due to the light-assisted tunneling effect. The prepared device configuration was ITO/(PEI/PAA)2/P3HT:PC60BM/Yb/Al. The performances of the OPDs were investigated by measuring the current–voltage characteristics, external quantum efficiency, and transient photocurrent. In addition, the operating mechanism of the OPDs was confirmed by impedance analysis. The device comprising (PEI/PAA)2 showed a specific detectivity of 3.11 × 1012 Jones and a bandwidth of 103.2 kHz at ?1 V and 525 nm. This performance is a numerical value that can be used in devices such as a line scan camera. In addition, because this device is fabricated by a low-temperature solution process, flexible and large-area substrates can be used.
关键词： light-assisted tunneling effect,organic photodetectors,PEI/PAA multilayers,p-type buffer layer,low-temperature solution process
更新于2025-09-16 10:30:52
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Single-walled carbon nanotube growth at low temperature by alcohol gas source method using Co catalyst: enhancement effects of Al<sub>2</sub>O<sub>3</sub> buffer layer on carbon nanotube yield
摘要： Using an alcohol gas source chemical vapor deposition method, we attempted to grow single-walled carbon nanotube (SWCNT) growth using Co catalysts on Al2O3 buffer layers. Reducing the growth temperature decreased the optimal ethanol pressure to obtain the highest SWCNT yield. By optimizing the ethanol pressure, we succeeded in growing SWCNTs at 400oC. Irrespective of the growth temperature, SWCNT yields from Co catalysts on Al2O3 buffer layers were higher than those on SiO2/Si substrates, but the enhancing effects of Al2O3 buffer layers on SWCNT yield were reduced below 500oC. Taking into account both in-plane X-ray diffraction results and decrease of catalyst aggregation in the low temperature region, we concluded that the density of Co particles suitable for SWCNT growth increased on SiO2 surface at low temperature, resulting in the reduction of difference in SWCNT yield at low temperature between Al2O3 buffer layers and SiO2/Si substrates.
关键词： catalyst,CVD,low-temperature growth,single-walled carbon nanotube,Co
更新于2025-09-16 10:30:52
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Flexible CZTSSe thin film solar cells fabricated at low temperature with relieved residual stress by Sb incorporation
摘要： The troublesome residual stress is always a stumbling block that drags the progress pace of flexible CZTSSe thin film solar cells, which urgently needs to be noticed and solved. In this paper, low-temperature prepared CZTSSe absorber with relieved residual stress (0.558 GPa) is realized by Sb incorporation. Owing to the evaporated 20 nm Sb layer under CZTS precursor, the crystalline quality and band mismatching of CZTSSe/CdS interface are simultaneously improved. Additionally, the spatial potential fluctuation extracted from the PL results is found to decrease from 63.26 meV to 41.57 meV, indicating a reduction in band tailing and disorder of CZTSSe absorber. Compared with the general solar cells fabricated at 580 °C, flexible devices with Sb incorporation can maintain a slightly higher performance at a lower temperature about 60 °C. The best power conversion efficiency (PCE) of 4.41% is obtained in the solar cell with 550 °C-selenized CZTSSe absorber after incorporating 20 nm Sb layer, featuring 351.20 mV Voc, 25.73 mA/cm2 Jsc and 48.79% FF. Finally, low-temperature prepared flexible CZTSSe thin film solar cell can retain over 83% of the original PCE after bending at 180° for 40 cycles. The mechanical durability paves a promising way for flexible CZTSSe thin film solar cell in roll-to-roll production.
关键词： CZTSSe,Sb incorporation,Residual stress,Low temperature
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - St. Petersburg, Russia (2019.10.17-2019.10.18)] 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - A Method for Increasing the Low-Temperature Stability of Steady-State Behavior and Common-Mode Interference Resistance CJFET Dual-Input-Stages
摘要： An original input differential stage circuit (DS) on complementary junction field-effect transistors (CJFET) is proposed. Their main designated area is low-noise analog ICs for operation at low temperatures, including cryogenic ones. The special circuit design for setting steady-state behavior of the DS and its parametric optimization in the LTspice environment provide a relatively high stability of the CJFet steady-state behavior of the input transistors in a wide temperature range. It is shown that, in this case, the common- mode rejection ratio is increased.
关键词： low-temperature electronics,differential operational amplifier,LTspice environment,differential stage,common-mode rejection ratio,junction field-effect transistors
更新于2025-09-16 10:30:52
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Simulation to fabricationa??understanding the effect of NiAuCu alloy catalysts for controlled growth of graphene at reduced temperature
摘要： It is a significant challenge to grow large-scale, high quality, monolayer graphene at low temperature for the applications in industry, especially for the complementary metal oxide semiconductor fabrication process. To overcome this difficulty, we simulated the decomposition of acetylene (C2H2) on (100) surfaces of primarily nickel (Ni) catalysts with small mol fractions of gold (Au) and copper (Cu), using a 4×4×4 periodic supercell model. Based on the calculation of the reaction energies to decompose the C-H or C≡C bonds on different catalyst surfaces, a differential energy is proposed to clearly scale the decomposition difficulties such that larger differential energy leads to easier control of the monolayer growth. It is observed that on the NiAuCu alloy surface with a mol fraction 0.0313 of both Au and Cu, the differential energy of the C-H bonds and the C≡C bond are both positive, showing an obvious modulation effect on the decomposition of C2H2 and the catalytic activites. The simulation result is consistent with the growth of uniform monolayer graphene on silicon dioxide substrate at 500°C by plasma enhanced chemical vapor deposition with C2H2 precursor and Ni alloy catalysts with 1 wt% Au and 1 wt% Cu.
关键词： NiAuCu alloy catalyst,chemical vapour deposition,graphene,density function theory,low temperature
更新于2025-09-16 10:30:52
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Coupled photothermal and joule-heating process for stable and efficient interfacial evaporation
摘要： A trade-off inevitably exists between soot and NOX emissions in a traditional engine. The addition of an oxygen-containing biofuel can decrease the soot emission but increase the NOX emission. Multi-injection strategy can be used to decrease the NOX emission. Therefore, both simulations and experimental tests were conducted to evaluate the influences of pre-injection on the combustion and emission characteristics of pure diesel (D100) and diesel/n-butanol (30% n-butanol and 70% diesel by volume, B30). The results showed that as the pre-injection interval decreased, the in-cylinder pressure peak increased, the pre-injection heat release ratio increased, and the brake-specific fuel consumption (BSFC) decreased. Only at a small pre-injection interval, the BSFC under pre-injection condition was lower than that obtained using the single injection strategy. When the same pre-injection strategy was used, B30 had a higher BSFC and lower brake thermal efficiency than D100. The soot emission decreased with the increase in pre-injection interval but increased with the increase in pre-injection ratio. More soot was emitted using the pre-injection strategy than that using single injection strategy. B30 had a lower soot emission than D100 due to a longer ignition delay. As the pre-injection interval increased, the decreasing amplitude of NO production became smaller than the increasing amplitude of NO2 production, thus increasing the net NOX emission. As the pre-injection ratio increased, more CO was produced through the reaction paths CH2O → HCO → CO, whereas the transformation of CO to CO2 almost remained unchanged, thus increasing the net CO emission. The increase in pre-injection ratio inhibited the oxidation of CO to CO2 and thus increased the CO emission. The amount of unburned hydrocarbons increased with the increase in both pre-injection ratio and interval.
关键词： Chemical kinetics,CFD,Pre-injection,Diesel/n-butanol blends,Low-temperature combustion
更新于2025-09-16 10:30:52
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Pixel Circuit With Leakage Prevention Scheme for Low-Frame-Rate AMOLED Displays
摘要： This work proposes a new pixel circuit for active-matrix organic light-emitting (AMOLED) smartwatch displays with a low frame rate. Within the long emission period, the leakage current of a low-temperature polycrystalline silicon thin-film transistor (LTPS TFT) is reduced to suppress the distortion of the driving voltage at the gate node of the driving TFT. Based on the measured electrical characteristics of a fabricated p-type LTPS TFT, the HSPICE model is established to verify the feasibility of the proposed circuit. The analytical results indicate that the relative OLED current error rates are all below 4.73%, as the threshold voltage of TFT varies by ±0.5 V. Notably, the OLED current varies by only 2.94% during the emission period of 66.7 ms at a medium gray level, demonstrating the effectiveness of the leakage prevention scheme.
关键词： low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs),Active-matrix organic light-emitting diode (AMOLED),leakage current prevention
更新于2025-09-16 10:30:52
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Achieving efficient flexible perovskite solar cells with room-temperature processed tungsten oxide electron transport layer
摘要： For flexible perovskite solar cells, achieving high power conversion efficiency by using a room-temperature technology to fabricate a compact electron transport layer is one of the best options. Here, we develop an annealing-free, dopant-free, and amorphous tungsten oxide as electron transport layer by vacuum evaporation for flexible perovskite solar cells. The compact amorphous tungsten oxide electron transport layer with different thicknesses (0–50 nm) was directly deposited on flexible PEN/ITO substrate. A model of the improvement mechanism is proposed to understand how the thickness tailoring simultaneously enhances the crystallization and relaxes the trade-off between interface recombination and charge transfer. By optimizing the amorphous tungsten oxide thickness, the high homogeneous, uniform, and dense electron transport layer with a thickness of 30 nm is found to not only decrease the pinhole of the perovskite layer, but also enhance charge transport with reducing resistance. Furthermore, the mechanical bending stability revealed that, the fabricated perovskite solar cells show stable power conversion efficiency up to more than 1000 bending cycles. The room-temperature processed fabrication enables the amorphous tungsten oxide to become a potential electron transport layer candidate for the large-scale flexible perovskite solar cells, which becomes compatible with practical roll-to-roll solar cells manufacturing.
关键词： Electron transport layer,Amorphous tungsten oxides,Low temperature,Flexible solar cells,Interface recombination
更新于2025-09-16 10:30:52
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Remarkable Improvement in Foldability of Polya??Si Thina??Film Transistor on Polyimide Substrate Using Blue Laser Crystallization of Amorphous Si and Comparison with Conventional Polya??Si Thina??Film Transistor Used for Foldable Displays
摘要： Highly robust poly-Si thin-film transistor (TFT) on polyimide (PI) substrate using blue laser annealing (BLA) of amorphous silicon (a-Si) for lateral crystallization is demonstrated. Its foldability is compared with the conventional excimer laser annealing (ELA) poly-Si TFT on PI used for foldable displays exhibiting field-effect mobility of 85 cm2 (V s)-1. The BLA poly-Si TFT on PI exhibits the field-effect mobility, threshold voltage (VTH), and subthreshold swing of 153 cm2 (V s)-1, -2.7 V, and 0.2 V dec-1, respectively. Most important finding is the excellent foldability of BLA TFT compared with the ELA poly-Si TFTs on PI substrates. The VTH shift of BLA poly-Si TFT is ±0.1 V, which is much smaller than that (±2 V) of ELA TFT on PI upon 30 000 cycle folding. The defects are generated at the grain boundary region of ELA poly-Si during folding. However, BLA poly-Si has no protrusion in the poly-Si channel and thus no defect generation during folding. This leads to excellent foldability of BLA poly-Si on PI substrate.
关键词： grain boundary,polyimide substrates,protrusions,flexible low-temperature poly-Si thin-film transistors,blue laser annealing
更新于2025-09-16 10:30:52