Due to its single conduction band nature, it is highly challenging to enhance the power factor of SnSe 2 by band convergence. Here, it is reported that simultaneous Cu intercalation and Br doping induce strong Cu-Br interaction to connect SnSe 2 layers, otherwise isolated, via "electrical bridges." Atom probe tomography analysis confirms a strong attraction between Cu intercalants and Br dopants in the SnSe 2 lattice. Density functional theory calculations reveal that this interaction delocalizes electrons confined around SnSe covalent bonds and enhances charge transfer across the SnSe 2 slabs. These effects dramatically increase electron mobility and concentration. Polycrystalline SnCu 0.005 Se 1.98 Br 0.02 shows even higher electron mobility than pristine SnSe 2 single crystal and the theoretical expectation. This results in significantly improved electrical conductivity without reducing effective mass and Seebeck coefficient, thereby leading to the highest power factor of ≈12 µW cm −1 K −2 to date for polycrystalline SnSe 2 and SnSe. It even surpasses the value for the state-of-the-art n-type SnSe 0.985 Br 0.015 single crystal at elevated temperatures. Surprisingly, the achieved power factor is nearly independent of temperature ranging from 300 to 773 K. The engineering thermoelectric figure of merit ZT eng for SnCu 0.005 Se 1.98 Br 0.02 is ≈0.25 between 773 and 300 K, the highest ZT eng ever reported for any form of SnSe 2 -based thermoelectric materials.

Silicon carbide (SiC) has been widely concerned for its excellent overall mechanical and physical properties, such as low density, good thermal-shock behavior, high temperature oxidation resistance, and radiation resistance; as a result, the SiC-based materials have been or are being widely used in most advanced fields involving aerospace, aviation, military, and nuclear power. Joining of SiC-based materials (monolithic SiC and SiC f /SiC composites) can resolve the problems on poor processing performance and difficulty of fabrication of large-sized and complex-shaped components to a certain extent, which are originated from their high inherent brittleness and low impact toughness. Starting from the introduction to SiC-based materials, joining of ceramics, and joint strength characterization, the joining of SiC-based materials is reviewed by classifying the as-received interlayer materials, involving no interlayer, metallic, glass-ceramic, and organic interlayers. In particular, joining processes (involving joining techniques and parameter conditions), joint strength, interfacial microstructures, and/or reaction products are highlighted for understanding interfacial behavior and for supporting development of application-oriented joining techniques.

We exploit the Sn ratio to optimize the band alignment in Pb–Sn mixed triple perovskite solar cells with an inverted structure.

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