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Efficient flexible perovskite solar cells and modules using a stable SnO<sub>2</sub>-nanocrystal isopropanol dispersion
No full textThe outstanding advantages of lightweight and flexibility enable flexible perovskite solar cells (PSCs) to have great application potential in mobile energy devices. Due to the low cost, low-temperature processibility, and high electron mobility, SnO2 nanocrystals have been widely employed as the electron transport layer in flexible PSCs. To prepare high-quality SnO2 layers, a monodispersed nanocrystal solution is normally used. However, the SnO2 nanocrystals can easily aggregate, especially after long periods of storage. Herein, we develop a green and cost-effective strategy for the synthesis of high-quality SnO2 nanocrystals at low temperatures by introducing small molecules of glycerol, obtaining a stable and well-dispersed SnO2-nanocrystal isopropanol dispersion successfully. Due to the enhanced dispersity and super wettability of this alcohol-based SnO2-nanocrystal solution, large-area smooth and dense SnO2 films are easily deposited on the plastic conductive substrate. Furthermore, this contributes to effective charge transfer and suppressed non-radiative recombination at the interface between the SnO2 and perovskite layers. As a result, a greatly enhanced power conversion efficiency (PCE) of 21.8% from 19.2% is achieved for small-area flexible PSCs. A large-area 5 cm x 5 cm flexible perovskite solar mini-module with a champion PCE of 16.5% and good stability is also demonstrated via this glycerol-modified SnO2-nanocrystal isopropanol dispersion approach
Extracting Instruction Set Architecture Semantics from a Processor Register-transfer Level
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Numerical investigation of nanofluid buoyant flow behavior and heat transfer characteristics in annular-shaped enclosure with internal baffle
No full textPurpose
Natural convection in finite enclosures is a common phenomenon in various thermal applications. To provide the thermal design guidelines, this study aims to numerically explore the potential of using internal baffles and nanofluids to either enhance or suppress heat transport in a vertical annulus. Furthermore, the annular-shaped enclosure is filled with aqueous-silver nanofluid and the effects of five distinct nanoparticle shapes are examined. In addition, the influence of baffle design parameters, including baffle position, thickness and length, is thoroughly analyzed.
Design/methodology/approach
The finite difference method is used in conjunction with the alternating direction implicit and successive line over relaxation techniques to solve nonlinear and coupled partial differential equations. The single phase model is used for nanofluid which is considered as a homogeneous fluid with improved thermal properties. The independence tests are carried out for assessing the sufficiency of grid size and time step for obtaining results accurately.
Findings
The baffle dimension parameters and nanoparticle shape exhibit significant impact on the convective flow and heat transfer characteristics, leading to the following results: sphere- and blade-shaped nanoparticles demonstrate around 30% enhancement in the heat transport capability compared with platelet-shaped nanoparticles, which exhibit the least. When considering the baffle design parameter, either a decrease in the baffle length and thickness or an increase in baffle height leads to an improvement in heat transport rate. Consequently, a threefold increase in baffle height yields a 40% improvement in thermal performance.
Originality/value
Understanding the impact of nanoparticle shapes and baffle design parameters on flow and thermal behavior will enable engineers to provide valuable insight on thermal management and overall system efficiency. Therefore, the current work focuses on exploring buoyant nanofluid flow and thermal mechanism in a baffled annular-shaped enclosure. Specifically, an internal baffle that exhibits conductive heat transfer through it is considered, and the impact of baffle dimensions (thickness, length and position) on the fluid flow behavior and thermal characteristics is investigated. In addition, the current study also addresses the influence of five distinct nanoparticle shapes (e.g. spherical, cylindrical, platelet, blade and brick) on the flow and thermal behavior in the baffled annular geometry. In addition to deepening the understanding of nanofluid behavior in a baffled vertical annulus, the current study contributes to the ongoing advancements in thermal applications by providing certain guidelines to design application-specific enclosures
Suppressing Deformation of Silicon Anodes via Interfacial Synthesis for Fast-Charging Lithium-Ion Batteries
No full textSilicon anodes with high energy density are prone to mechanical deformation during cycling, including fracture, pulverization, and delamination from conductive materials, due to their large volume expansion and contraction. Although significant attention is paid to outer interface engineering such as surface coating and electrolyte design in order to maintain a steady solid electrolyte interphase (SEI), there are currently few strategies in place for stabilizing the inner interface between Si and conductive carbon host materials. In this work, it is reported that an interfacial SiC chemical bonding enhances the interaction between Si and carbon, which in turn suppresses nano-sized void evolution and ensues Si delamination. Through the open-edge structure of carbon nanotube (OCNT), it is demonstrated that graphitic edge planes enable to evoke of interfacial SiC specifically at the junction without overgrowth toward the bulk. As a result, an Si-graphite composite consisting of interfacial SiC exhibits a sF cycling life (79.5% for 300 cycles at 3C charging), as well as lower overpotential under high current density up to 5C compared to paired LiNi0.6Co0.2Mn0.2O2 (NCM) cathode in pouch full-cell tests. This study highlights the significance of inner interface engineering for developing high-energy density Si-based anodes toward fast charging and long-term stability
