With the construction and development of modern and smart cities, people's lives are becoming more intelligent and diversified. Surveillance systems increasingly play an active role in target ...tracking, vehicle identification, traffic management, etc. In the 6G network environment, facing the massive and large-scale data information in the monitoring system, it is difficult for the ordinary processing platform to meet this computing demand. This paper provides a data governance solution based on a 6G environment. The shortcomings of critical technologies in wireless sensor networks are addressed through ZigBee energy optimization to address the shortage of energy supply and high energy consumption in the practical application of wireless sensor networks. At the same time, this improved routing algorithm is combined with embedded cloud computing to optimize the monitoring system and achieve efficient data processing. The ZigBee-optimized wireless sensor network consumes less energy in practice and also increases the service life of the network, as proven by research and experiments. This optimized data monitoring system ensures data security and reliability.
Here, we investigate photoluminescence (PL) and time-resolved photoluminescence (TRPL) in CH3NH3PbBr3 perovskite under continuous illumination, using optical and electro-optical techniques. Under ...continuous excitation at constant intensity, PL intensity and PL decay (carrier recombination) exhibit excitation intensity dependent reductions in the time scale of seconds to minutes. The enhanced nonradiative recombination is ascribed to light activated negative ions and their accumulation which exhibit a slow dynamics in a time scale of seconds to minutes. The observed result suggests that the organic–inorganic hybrid perovskite is a mixed electronic–ionic semiconductor. The key findings in this work suggest that ions are photoactivated or electro-activated and their accumulation at localized sites can result in a change of carrier dynamics. The findings are therefore useful for the understanding of instability of perovskite solar cells and shed light on the necessary strategies for performance improvement.
In this work, we report the benefits of incorporating phenethylammonium cation (PEA+) into (HC(NH2)2PbI3)0.85(CH3NH3PbBr3)0.15 perovskite for the first time. After adding small amounts of PEA cation ...(<10%), the perovskite film morphology is changed but, most importantly, grain boundaries are passivated. This is supported by Kelvin Probe Force Microscopy (KPFM). The passivation results in the increase in photoluminescence intensity and carrier lifetimes of test structures and open-circuit voltages (V OC) of the devices as long as the addition of PEA+ is ≤4.5%. The presence of higher-band-gap quasi-2D PEA incorporated perovskite is responsible for the grain boundary passivation, and the quasi-2D perovskites are also found to be concentrated near the TiO2 layer, revealed by PL spectroscopy. Results of moisture exposure tests show that PEA+ incorporation is effective in slowing down the degradation of unencapsulated devices compared to the control devices without PEA+. These findings provide insights into the operation of perovskite solar cells when large cations are incorporated.
Cesium (Cs) metal halide perovskites for photovoltaics have gained research interest due to their better thermal stability compared to their organic–inorganic counterparts. However, demonstration of ...highly efficient Cs-based perovskite solar cells requires high annealing temperature, which limits their use in multijunction devices. In this work, low-temperature-processed cesium lead (Pb) halide perovskite solar cells are demonstrated. We have also successfully incorporated the less toxic strontium (Sr) at a low concentration that partially substitutes Pb in CsPb1–x Sr x I2Br. The crystallinity, morphology, absorption, photoluminescence, and elemental composition of this low-temperature-processed CsPb1–x Sr x I2Br are studied. It is found that the surface of the perovskite film is enriched with Sr, providing a passivating effect. At the optimal concentration (x = 0.02), a mesoscopic perovskite solar cell using CsPb0.98Sr0.02I2Br achieves a stabilized efficiency at 10.8%. This work shows the potential of inorganic perovskite, stimulating further development of this material.
The double-disc straight-groove (DDSG) grinding method is a new precision machining approach employed for the rolling surface of bearing rollers. The friction coefficient and wear resistance of ...grinding disc materials affect the grinding performance due to the operation on the workpiece. However, relevant research on DDSG is rather limited currently. Therefore, we analyzed the friction principles of the DDSG method and conducted friction and wear experiments to facilitate appropriate material selection for grinding discs. The optimal friction conditions for grinding disc materials were determined to ensure steady rotation of cylindrical rollers. In addition, the friction coefficients, wear resistance, and clogging resistance of various materials such as PTFE, PMMA, cast iron, brass, and fixed abrasives were measured by friction and wear experiments under grinding conditions. The friction pairs of PMMA-AISI 52100 and PTFE-AISI 52100 exhibited sliding friction coefficients of 0.14 and 0.03, respectively, along with a high grinding efficiency and excellent wear resistance. The friction pairs of both bearing steel-fixed abrasive and bearing steel-brass were easily clogged, leading to dramatic changes in the sliding friction coefficients, and neither fixed abrasive nor brass was found to be a suitable material for grinding discs. Thus, PMMA and PTFE were selected as the materials for upper and lower grinding discs. Moreover, a verification platform was built to implement the DDSG grinding method where a continuous rotation of ground roller was observed. Overall, this study provides a basis for feasible material selection and an appropriate material combination for designing a grinding machine based on DDSG.
A spin-coating-free fabrication sequence has been developed for the fabrication of highly efficient organic-inorganic halide perovskite solar cells (PSCs). A novel blow-drying method is demonstrated ...to be successful in depositing high quality mesoporous TiO2 (mp-TiO2), methylammonium lead halide (CH3NH3PbI3) perovskite and spiro-MeOTAD layers. When combined with compact TiO2 (c-TiO2) deposited by spray pyrolysis which is also a spin-coating-free process, a stabilized power conversion efficiency exceeding 17% can be achieved for the glass/FTO/c-TiO2/mp-TiO2/ CH3NH3PbI3/spiro-MeOTAD/Au device. This is the highest efficiency for PSCs fabricated without the use of spin-coating to our knowledge. This method provides a pathway towards a scalable process for fabricating high-performance, large area and reproducible PSCs.
A spin-coating-free fabrication sequence has been developed for the fabrication of highly efficient PSCs with a stabilized PCE exceeding 17%. Display omitted
•17% efficiency perovskite solar cells (PSCs) fabricated without the use of spin-coating.•Systematic study on device performances when spin-coating process for each layer in the PSC is replaced by blow-drying.•Blow-dried perovskite and spiro‐MeOTAD layers are better than their spin-coated counterparts.
Metal halide perovskite solar cells that use the inorganic cation Cs have been shown to have better thermal stability than the organic cation containing counterparts, and CsPbI2Br has a more suitable ...(lower) band gap than CsPbIBr2 as a photovoltaic energy harvesting material. However, increase in iodine content reduces structural stability due to the preference toward the non-perovskite orthorhombic phase when the film is exposed to air. In this work, the effect of varying stoichiometry of CsPbI2Br perovskite on film quality such as the grain size, presence of impurities and nature of impurity grains, photoluminescence, morphology, and elemental distribution are studied. Details on how to vary the stoichiometry during the dual source thermal evaporation process are reported. It is found that the air stability of CsPbI2Br film correlates with the CsBr-to-PbI2 deposition rate ratio, in which the CsBr-rich CsPbI2Br is the most stable upon air exposure, while the stoichiometrically balanced CsPbI2Br perovskite film gives the best photovoltaic performance. The encapsulated device maintains 90% of the initial performance after 240 h damp and heat test at 85 °C and 85% relative humidity.
The region known as the Xiong'an New Area serves as a testing and validation research laboratory for the development and utilization of geothermal energy in China. To better understand the ...lithospheric structure and associated geothermal features in the region, a comprehensive approach was employed, combining deep seismic reflection and an overlapping magnetotelluric sounding (MT) profile analysis. The analysis reveals arched reflections, coinciding with a relatively high-resistivity anomaly, demonstrating concentric patterns that indicate the presence of lithospheric gneiss domes beneath the Rongcheng and Niutuozhen structural highs. Additionally, the seismic image reveals a marked transparent zone characterised by low-resistivity beneath the Niubei slope. These dome-like features are interpreted as plutons and/or intrusive bodies that were formed by upwelling of the asthenosphere during the early Paleogene era. These relatively deep-rooted plutons are highly likely to be the primary heat sources in this geothermal region. Deep-seated faults beneath the Niubei slope act as channels, allowing the flow of fluids and the transfer of heat from the source to shallower levels. Isotope data supports that the notion that near-surface water flows through a shallow network of fractures, ultimately reaching the geothermal reservoir. The interpreted geometry suggests that the gneiss domes likely resulted from a Rayleigh-Taylor instability process. This process involves diapiric flow induced by density inversion, leading to an upwelling of the asthenosphere. These dynamics, superimposed onto a melted layered structure, generate the distinctive arcuate seismic reflectors found at the core of these domes. Surface geology analysis indicates that the initiation and final emplacement of these domes most likely occurred during the late Mesozoic period.
•The deep seismic reflection and an overlapping MT profile were integrated to constrain the lithospheric-scale structure and its associated geothermal features beneath beneath the Xiong'an New Area;•The arched reflections with high-resistivity indicate the presence of lithospheric-scale gneiss domes;•The transparent reflection with low-resistivity is interpreted as intrusive bodies and act as heating sources for geothermal field.
We apply gas quenching to fabricate rubidium (Rb) incorporated perovskite films for high-efficiency perovskite solar cells achieving 20% power conversion efficiency on a 65 mm2 device. Both ...double-cation and triple-cation perovskites containing a combination of methylammonium, formamidinium, cesium, and Rb have been investigated. It is found that Rb is not fully embedded in the perovskite lattice. However, a small incorporation of Rb leads to an improvement in the photovoltaic performance of the corresponding devices for both double-cation and triple-cation perovskite systems.
Short minority carrier lifetime and low open circuit voltage (Voc) are key issues limiting the current efficiency development for Cu2ZnSnS4 (CZTS) thin film solar cells. This work presents the use of ...Cd ion soaking and post-heat treatment to increase the lifetime and Voc of CZTS. The time-resolved photoluminescence (TRPL) results confirmed that Cd ion soaking and post heat treatment is effective in enhancing the minority lifetime, from ∼10 ns up to ∼28 ns. With analyses of the current density- voltage (J-V) curves and external quantum efficiency (EQE) data, Cd ion soaking and subsequent post heat treatment is found to greatly reduce the recombination and improve the junction quality, contributing to a ∼70 mV Voc enhancement and resulting in the increased device efficiency of 7.6%, from 5.9%.
•Cd ion soaking with related post annealing effectively boost efficiency of CZTS solar cell.•PL technologies reveal the significant enhanced minority lifetime.•7.6% power conversion efficiency has been achieved for sol-gel CZTS solar cell.
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