This work systematically investigated the thermoelectric properties of p-type Na and M (M = K, Li, Ag) codoped polycrystalline SnSe. It is found that the electrical properties of polycrystalline SnSe can be improved significantly for (Na, Ag) codoped samples, contributed by the enhanced carrier concentration. Specifically, a carrier concentration of 6.23 × 1019 cm–3 was obtained in Sn0.98Na0.016Ag0.004Se sample at 335 K, an increase of 18% compared with that of the Na single-doped sample (5.22 × 1019 cm–3). The power factor reached ∼0.73 mW m–1 K–2 for the Sn0.98Na0.016Ag0.004Se sample at 785 K, enhanced by ∼26% compared with Na single-doped one. In addition, Sn-rich and Ag-rich particles/areas observed in the matrix of Sn0.98Na0.016Ag0.004Se contribute to the reduction of lattice thermal conductivity from 0.61 W m–1 K–1 for Sn0.98Ag0.02Se to 0.47 W m–1 K–1 at 785 K. The combination of simultaneously enhanced power factor and depressed thermal conductivity leads to a maximum ZT ≈ 1.2 at 785 K and a high average ZT ≈ 0.74 at 335–785 K for Sn0.98Na0.016Ag0.004Se, and generating a high theoretical conversion efficiency of ∼11%. These illuminating discoveries could provide routes to enhance the thermoelectric performance in p-type polycrystalline SnSe.

stretchable conductor is to disperse conductive 0D, 1D, and 2D nanomaterials onto soft elastomeric substrates. These include nanoparticles, [6][7][8] carbon nanotubes, [9][10][11] silver nanowires, [12][13][14] and graphene, [15][16][17][18][19] all of which have demonstrated high conductivity and large stretchability. Another method is based on geometry, where thin conductive layers with micro/nanoscale corrugated structure maintain conductivity by unbending during stretching. These structures can be induced by surface buckling [19][20][21][22] or self-assembled patterns. [23] Our recent work has demonstrated that interference lithography and atomic layer deposition (ALD) can be used to create a freestanding nano-accordion structure, [24,25] which can be simultaneously stretchable, conductive, and transparent. This approach allows precise control of the structure period, height, and thickness to allow independent design of material properties. However, this approach relies on ALD of the conductive film, which has high cost and long deposition time. The ability to obtain conformal thinfilm coating using a low-cost process can facilitate scale-up manufacturing and broad implementation of flexible electronics.ALD is a widely employed vapor phase technique, where two gas precursors are introduced in alternating cycles to create a self-limited surface reaction. [26,27] Each cycle result in a single monolayer coating, allowing precise control of film thickness by using discrete cycles. Since the gas precursors can permeate within rough topography and deep pores, ALD has demonstrated conformal coating in high-aspect-ratio grating structures, [24,25] high-density nanoscale features, [28,29] and 3D porous lattice. [30][31][32][33][34] However, ALD also has a number of drawbacks, such as long reaction time and expensive precursor gases, contributing to high process cost. Compared with physical vapor deposition (PVD), the selection of deposition material is also limited. Furthermore, metal ALD generally requires high synthesis temperature, which can be problematic for polymer surfaces or template structures.A more established alternative is PVD, which is one of the most widely used technique for precise deposition of thin films, including metals and a diverse range of organic/inorganic materials. Representing a class of techniques where the Physical vapor deposition (PVD) is a versatile thin-film coating technique that can deposit a wide selection of inorganic materials at low cost. However, the process is based on line-of-sight transfer, which can lead to shadowing effects and limit film uniformity over nonplanar topographies. This work describes improving conformal PVD coating on polymer nanostructures by increasing surface energy using a thin oxide interlayer deposited by atomic layer deposition (ALD). The proposed ALD-assisted PVD process allows conformal coating at low cost, and can be adopted for a wide variety of materials compatible with tradition PVD. Conformal gold films over nanostructures with 500 nm half-pitch...

Physical vapor deposition of thin films on nanostructure topography is typically limited by line‐of‐sight transfer. This study demonstrates that by introducing an oxide interlayer using atomic layer deposition, the film uniformity and electrical properties can be improved. Enabling conformal coating at low cost, this method can find applications in manufacturing of integrated circuit and stretchable electronics. More details can be found in article number https://doi.org/10.1002/admi.201801379 by Joong‐Hee Min, Chih‐Hao Chang, and co‐workers.

The detection of sulfur hexafluoride (SF 6 ) decomposition components has become one of the best ways to diagnose early latent insulation faults in gas-insulated equipment, which can effectively prevent sudden accidents by identifying such faults. In this paper, we by first-principles theory investigated the adsorption and sensing behaviors of four typical SF 6 decomposition components (H 2 S, SO 2 , SOF 2 , and SO 2 F 2 ) on the pristine Pd-doped MoTe 2 monolayer. The adsorption energy, work function, recovery time, charge density difference, density of state, and band structure of the adsorption structures are obtained as well as analyzed. The results indicate that the Pd dopant prefers to be trapped at the T Mo site, with a binding energy of −2.25 eV. The Pd-MoTe 2 chemisorbs the remaining gases except SO 2 xF 2 , with the adsorption capacity ranking as SOF 2 > SO 2 > H 2 S. The adsorption of gas molecules reduces the bandgap of Pd-MoTe 2 , thereby increasing conductivity. On the other hand, the recovery time of the Pd-MoTe 2 monolayer material at a temperature of 398 K demonstrates its excellent gas desorption performance toward four decomposition gases. The research results provide a theoretical basis for Pd-MoTe 2 to detect SF 6 decomposition components, thus, promoting the stable operation of the power system.