Organic-inorganic perovskite materials are revolutionizing photovoltaics with high power conversion efficiencies, but experience significant environmental degradation and instability. In this work, the phase stability and decomposition mechanisms of lead-free all inorganic Cs₂SnI₆ perovskite upon water and moisture exposure were systematically investigated via in situ synchrotron X-ray diffraction, environmental SEM, and micro-Raman spectroscopy. A critical relative humidity (80%) is identified below which Cs₂SnI₆ perovskite is stable without decomposition. Under higher humidity or aqueous environment, Cs₂SnI₆ perovskite decomposes into SnI₄ and CsI through etch pits formation and stepwave propagation, leading to rapid crystal dissolution. A partial reversibility of the Cs₂SnI₆ perovskite upon dissolution and re-precipitation with subsequent dehydration was identified, suggesting a self-healing capability of Cs₂SnI₆ and thus enhanced air stability. Mechanistic understanding of the Cs₂SnI₆ degradation behavior can be a vital step towards developing new perovskites with enhanced environmental stability and materials performance.

Two-dimensional (2D) nanosheets have been assembled into various macroscopic structures for wide engineering applications. To fully explore their exceptional thermal, mechanical, and electrical properties, 2D nanosheets must be aligned into highly ordered structures due to their strong structural anisotropy. Structures stacked layer by layer such as films and fibers have been readily assembled from 2D nanosheets due to their planar geometry. However, scalable manufacturing of macroscopic structures with vertically aligned 2D nanosheets remains challenging, given their large lateral size with a thickness of only a few nanometers. Herein, we report a scalable and efficient microfluidics-enabled sheet-aligning process to assemble 2D nanosheets into a large-area film with a highly ordered vertical alignment. By applying microchannels with a high aspect ratio, 2D nanosheets were well aligned vertically under strong channel size confinement and high flow shear stress. A vertically aligned graphene sheet film was obtained and applied to effectively improve the heat transfer of thermal interfacial materials (TIMs). Superior through-plane thermal conductivity of 82.7 W m⁻¹ K⁻¹ at a low graphene content of 11.8 vol% was measured for vertically aligned TIMs. Thus, they demonstrate exceptional thermal management performance for switching power supplies with high reliability.

This paper presents an investigation of reverse recovery phenomenon for SiC devices in high temperature applications (from 25 °C to 250 °C). First, the mechanism of reverse recovery is analyzed and corresponding influencing factors are analysed. A piecewise equivalent circuit model is proposed to analyse reverse recovery. Second, two mismatch conditions which may worsen the reverse recovery are also introduced when anti-parallel Schottky barrier diodes are used. It is found that the device layout of power module and dead-time control also affect reverse recovery. It is also found that a short enough or long enough dead-time can suppress reverse recovery to some extent, while a moderate dead-time may lead to the most severe reverse recovery in PN-CELL layout. Finally, different methods for reverse recovery suppression are summarized and compared.

Flexible fast-charging sodium ion storage devices are poised to transform the future wearable electronics industry, if the materials used to build such devices can present a versatile integration. Herein, inspired by ferroconcrete, nonwoven graphene fiber (GF) fabric reinforced electrodes were successfully demonstrated in flexible sodium ion capacitors (SICs). For the fabrics, the functionalities of fast electron transport and an ion permeation network, a highly compatible electrode material host, an efficient capacity contributor, and a robust flexible framework are synergistically integrated. These were provided by the high conductivity of the graphene sheets, the tunable porosity of the GF, and the interlocked structure, compatibility with materials, and the surface capacitive contribution of the fabrics. The nonwoven fabrics hosted multi-dimensional active materials as the ferroconcrete electrode exhibits exceptional electrochemical and mechanical properties individually. The SICs can complete an entire charge–discharge process within 15 s. A digital LED and watch powered using the flexible SICs with superior volumetric performances (12 mW h cm⁻³@37 mW cm⁻³, and 6 mW h cm⁻³@1.9 W cm⁻³) proved the practical capability of our design. We believe that the proposed nonwoven GF fabrics and the ferroconcrete electrode structure will become a universal design, and shed new light on flexible fast-charging sodium ion storage devices.

The continued miniaturization of chips demands highly thermally conductive materials and effective thermal management strategies. Particularly, the high‐field transport of the devices built with 2D materials is limited by self‐heating. Here a systematic control of heat flow in single‐side fluorinated graphene (FG) with varying degrees of fluorination is reported, revealing a superior room‐temperature thermal conductivity as high as 128 W m⁻¹ K⁻¹. Monolayer graphene/FG lateral heterostructures with seamless junctions are approached for device fabrication. Efficient in‐plane heat removal paths from graphene channel to side FG are created, contributing significant reduction of the channel peak temperature and improvement in the current‐carrying capability and power density. Molecular dynamics simulations indicate that the interfacial thermal conductance of the heterostructure is facilitated by the high degree of overlap in the phonon vibrational spectra. The findings offer novel design insights for efficient heat dissipation in micro‐ and nanoelectronic devices.

Multiphysics simulation software is indispensable for SiC power module design. Lacking interface between circuit simulation software and thermal-fluid-mechanical simulation software poses challenges for accurate design of the power modules. In this paper, an automated field-circuit coupling simulation method based on the self-developed COMSOL-PSpice interface software is proposed to achieve precise and fast multiphysics co-simulation of multichip SiC power modules. Firstly, the multiphysics coupling mechanism of SiC power modules is analyzed to reveal that the precise and timely data transfer between temperature and power loss is crucial to enabling an accurate multi-software co-simulation. To realize the automatic data transfer between COMSOL and PSpice, a MATLAB-based software interface is developed. Then, a multi-rate and indirect coupling strategy is proposed to improve the simulation accuracy of the developed COMSOL-PSpice software interface and speed up the co-simulation process. To break the limitations of the indirect coupling strategy on simulation accuracy and efficiency with fixed time steps, a variable time step coupling analysis method based on the numerical solution of temperature coupling state variables is proposed. Finally, the proposed field-circuit coupling co-simulation method is verified by simulation and experiment results from a buck converter. The comparison between simulation and experimental results demonstrates the validity of the developed co-simulation interface software, which gives a mismatch below 5% and simulation efficiency 3-5 times higher, if compared to that using fixed time steps.