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Nanostructured skutterudite p-type CoSb 3(1+ δ ) ( δ =0.00, 0.01 and 0.02) samples are synthesized via a combination of solvothermal synthesis and evacuating-and-encapsulating sintering. All the samples are of single phase with cubic structure. The thermopower of all the samples is positive, indicating that the predominant carriers are hole in the temperature range of 300–700 K. Both the electrical resistivity and thermopower follow the variable range hopping process for 300≤ T ≤425 K. The power factor of all samples exhibits a monotonic increase with temperature up to 700 K. The highest power factor is obtained for CoSb 3(1+ δ ) with δ =0.01, which represents 145% increase when compared to CoSb 3 with δ =0.00. The ZT value is 0.07 at 550 K for CoSb 3(1+ δ ) with δ =0.01, representing an improvement of about 95% compared to CoSb 3 with δ =0.00. These results suggest that excess antimony provides an effective avenue of improving the thermoelectric properties of CoSb 3.

Polycrystalline p-type Ce x Co 4 Sb 12.04 with x =0.15, 0.20 and 0.30 are fabricated using a combination of solvothermal synthesis at 260 °C for 24 h and evacuated-and-encapsulated heating at 600 °C for 5 h. The X-ray diffraction patterns reveal that all the compositions are of single phase. The thermopower of all the samples is positive, indicating that the predominant carriers are holes over the investigated temperature range of 80–300 K. The electrical resistivity and thermopower simultaneously decrease with increasing Ce filling content. Analyses of the temperature dependence of both electrical resistivity and thermopower indicate that all the samples obey the variable range hopping transport mechanism. Among the samples, Ce 0.20 Co 4 Sb 12.04 exhibits the highest power factor of 0.29 μW cm −1 K −2 at 300 K. This value represents an improvement of about 556% compared to pristine Co 4 Sb 12.04 .

A low-voltage and low-control-loss RF-dc rectifier with high power conversion efficiency (PCE) at 13.56 MHz band is presented in this paper. This is achieved by utilizing novel reducing reverse loss (RRL) techniques to reduce the reverse leakage current loss. Higher output voltage can also be generated by the multistage stacking method with RRL technology. A boost-type front-end converter composed of an RF-dc rectifier with the RRL technique and a boost converter operating in a discontinuous-conduction mode are also proposed. The single-stage, three-stage pump-type RF-dc rectifier and the boost-type front-end rectifier have been implemented in TSMC 0.18 μm 1P6M technology. Experimental results show that the maximum PCE of the single-stage and three-stage pump-type RF-dc active rectifiers are 68.6% and 67.9% with input powers of 4.9 and 12.8 dB·m, respectively. The maximum PCE of the boost-type front-end converter is 41.3% with 1.2 dB·m input power.

The fabrication and detailed electrical properties of heterojunction diodes based on n-type SnS (n-SnS) and p-type Si (p-Si) were reported. The effect of sulfide treatment of p-Si on the power conversion efficiency (PCE) of the n-SnS/unpolished p-Si solar cell was investigated. The n-SnS/unpolished p-Si device without sulfide treatment showed a rectifying behavior with an ideality factor (@h) of 1.6 and high series resistance (R"s). However, the n-SnS/unpolished p-Si diode with sulfide treatment for 40s showed a good rectifying behavior with @h of 1.4 and low R"s. Therefore, the enhanced PCE can be interpreted by the device rectifying performance and interface passivation. In addition, note that a suitable sulfide treatment time is an important issue for producing high-efficiency solar cells.

This study investigates the effect of Mn content on the structural, luminescence and ferromagnetic properties of the sol–gel Zn 1− x Mn x S y films by X-ray diffraction (XRD), photoluminescence (PL), energy dispersive spectrometer and alternating gradient magnetometer measurements (AGM). Dependences of optical properties and crystal structure upon Mn content were found. In addition, combining with PL, XRD and AGM results, a direct link between the magnetization and defects of Zn 1− x Mn x S y films was established.

The effect of S content on the electrical property of the sol–gel SnS x films was examined. The observed conduction-type changes are related to the different ratios between the concentrations of Sn 4+ and Sn 2+ . The experimental identification confirms that n-type conversion is due to an increase in the atomic concentration ratio of Sn 4+ /(Sn 4+ + Sn 2+ ) in the S-rich film. The probability of having formed Sn vacancies (V Sn ) should be high under S-rich growth conditions. Transformation from V Sn to V Sn 2 - is accompanied by lattice relaxation. Therefore, transformation from Sn 2+ to Sn 4+ is an offset to lattice relaxation under S-rich growth conditions, increasing the electron density and producing n-type conversion. A suitable sulfur concentration is an important issue for tuning conduction type of SnS x .

Various reaction temperatures have been investigated to stabilize the CoSb3 phase obtained by a modified polyol process using a refluxing condenser. The resulting powders were cold-pressed and sintered in an evacuated-and- encapsulated ampoule for transport measurements. Single-phase CoSb3 could be produced for the reaction carried out at 448 K for a short duration of 15 min followed by evacuated-and-encapsulated sintering at 848 K for 5 h. In comparison with the sample sintered at 798 K, the sample sintered at 848 K exhibits lower resistivity and thermopower. Due to the sign crossover of the thermopower, the latter sample shows lower power factor for temperatures above 475 K.

p-type conduction of CuAlO2 thin films was realized by the rf sputtering method. Combining with Hall, X-ray photoelectron spectroscopy, energy dispersive spectrometer, and X-ray diffraction results, a direct link between the hole concentration, Cu vacancy (V Cu ), and interstitial oxygen (Oi) was established. It is shown that peroxidation of CuAlO2 films may lead to the increased formation probability of acceptors (V Cu and Oi), thus, increasing the hole concentration. The dependence of the V Cu density on growth conditions was identified for providing a guide to tune the formation of p-type defects in CuAlO2. Understanding the defect-related p-type conductivity of CuAlO2 is essential for designing optoelectronic devices and improving their performance.