In addition, it is of importance to note that a high power factor ( S 2 / ρ ) is also indispensable for a given TE material to maximize its output power. [ 3 ] Therefore, by taking account of the practical application, a simultaneously optimization in the electrical and thermal transport properties of TE materials is imperative to maximize the output power and conversion efficiency concurrently. Recently, some strategies have been proved to be effective and even high ZT values greater than 2.0 have been achieved in the Pb-based TE materials, [ 4,5 ] such as the band convergence, [ 6 ] electronic density of states (DOS) distortion, [ 7 ] carrier energy barrier fi ltering, [ 8 ] and the conduction (valence) band modifi cation [ 9 ] to enhance Seebeck coefficient for high power factor; while defect engineering, [ 10 ] nanostructuring, [ 11 ] and multiscale hierarchical architecturing [ 12 ] to enhance the scattering of phonons for low thermal conductivity. However, the environmentally hazardous Pb element prevents them from widespread application. Therefore, it is of signifi cance to develop eco-friendly TE materials for middle temperature application, such as Mg 2 Si, [ 13 ] Half-Heusler, [ 14 ] and BiCuSeO [ 15 ] based TE materials.More recently, chalcopyrite CuInTe 2 is being considered as a promising p-type TE material because of the merits of environmentally friendly chemical component, intrinsically high electrical conductivity, and high Seebeck coeffi cient owing to the degenerate energy bands near the valence band maximum (VBM). [ 16 ] Thus many efforts have been made theoretically and experimentally [17][18][19][20][21][22] to enhance its TE performance already, such as Cu defi ciency and cation substitution. However, since there are two cation sites (Cu and In) in CuInTe 2 , cation substitution often lacks specifi city and may generate both electron and hole simultaneously, making it diffi cult to enhance the electrical transport properties substantially. Besides, the less phonon scattering, mainly by point defects originated from chemical component regulation, rendering its thermal conductivity is still relatively high. It is well known that refi ning the microstructure into nanoscale is often effective in optimizing thermal transport properties, yet the electrical transport properties are usually deteriorated due to the inevitably scattering of carriers, as typical shown in the CuInTe 2 /graphene [ 23 ] and our

We report the fabrication and characterization of CdS/TiO(2) nanotube-array coaxial heterogeneous structures. Such structures may potentially be applied in various photocatalytic fields, such as water photocatalytic decomposition and toxic pollutant photocatalytic degradation. Thin films of CdS are conformally deposited onto TiO(2) nanotubes using a modified method of electrochemical atomic layer deposition. We propose that such nanostructured electrodes can overcome the poor absorption and high charge-carrier recombination observed with nanoparticulate films. The practical electrochemical deposition technique promotes the deposition of CdS onto the TiO(2) tube walls while minimizing deposition at the tube entrances, thus preventing pore clogging. The coaxial heterogeneous structure prepared by the new electrochemical process significantly enhances CdS/TiO(2) and CdS/electrolyte contact areas and reduces the distance that holes and electrons must travel to reach the electrolyte or underlying conducting substrate. This results in enhanced photon absorption and photocurrent generation. The detailed synthesis process and the surface morphology, structure, elemental analysis, and photoelectrochemical properties of the resulting films with the CdS/TiO(2) nanotube-array coaxial heterogeneous structure are discussed. In comparison with a pure TiO(2) nanotube array, a 5-fold enhancement in photoactivity was observed using the coaxial heterogeneous structure. This methodology may be useful in designing multijunction semiconductor materials for coating of highly structured substrates.

We studied the effect of doping with Bi on the thermoelectric properties of SnTe-based materials.

Nowadays, inorganic CsPbBr 3 perovskite is emerging as a promising candidate as a light-absorbing layer in photovoltaic devices due to its excellent photoelectric property and superior stability under humidity and thermal attacks in comparison with organic cation-based hybrid perovskites. However, the impure perovskite phase and severe interfacial charge recombination have limited the further improvement of device performance. In this work, a vapor-assisted solution technique was introduced to prepare a high-purity CsPbBr 3 film in a perovskite solar cell (PSC). To further reduce the electron−hole recombination and enhance charge extraction, we introduced the novel intermediate energy level of manganese sulfide (MnS) as a hole transport layer in CsPbBr 3 PSC. The as-optimized CsPbBr 3 PSC based on all-inorganic transport layers delivers a power conversion efficiency (PCE) of 10.45% in comparison with 8.16% for the device free of an intermediate layer, which is one of the highest PCEs achieved among the CsPbBr 3 -based PSCs to date. Moreover, the optimized device retained 80% PCE of its initial efficiency over 90 days under 80% relative humidity at 85 °C, indicating an excellent environmental tolerance to boost the commercial application of low-cost, efficient, and stable all-inorganic PSCs.

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