The increasing demands of environmental protection have led to solid lubricant coatings becoming more and more important. A new type of MoS₂-based coating co-doped with Cu and Al prepared by magnetron sputtering, including Cu/MoS₂ and Cu-Al/MoS₂ coatings, for lubrication applications is reported. To this end, the coatings were annealed in an argon atmosphere furnace. The microstructure and the tribological properties of the coatings prior to and following annealing were analyzed using scanning electron microscopy, energy dispersive spectrometry, X-ray diffractometry (XRD) and with a multi-functional tester for material surface properties. The results demonstrated that the friction coefficient of the Cu/MoS₂ coating was able to reach as low as 0.07, due to the synergistic lubrication effect of the soft metal Cu with MoS₂. However, the wear resistance of the coating was not satisfied. Although the lowest friction coefficient of the Cu-Al/MoS₂ coatings was 0.083, the wear resistance was enhanced, which was attributed to the improved the toughness of the coatings due to the introduction of aluminum. The XRD results revealed that the γ₂-Cu₉Al₄ phase was formed in the specimen of Cu-Al/MoS₂ coatings. The comprehensive performance of the Cu-Al/MoS₂ coatings after annealing was improved in comparison to substrate heating, since the heat-treatment was beneficial for the strengthening of the solid solution of the coatings.

This paper investigates the underlying mechanisms of Ti and Al doped into ZnO/MoS₂ coatings to develop better tribological properties for MoS₂-based lubrication coatings. To this end, Ti-ZnO/MoS₂ and Al-ZnO/MoS₂ coatings with gradient processing were successfully prepared using magnetron co-sputtering with a subsequent annealing treatment. The effects of Ti and Al on the structures and properties of ZnO/MoS₂ coatings were analyzed using various analytical methods. The results showed that Ti-ZnO/MoS₂ coatings annealed at 300 °C displayed a minimum friction coefficient of 0.07, and Al-ZnO/MoS₂ coatings annealed at 300 °C possessed the best oxidation resistance during wear process. Similarly, the highest nano-hardnesses of Ti and Al doped coatings were 1.9 GPa and 2.0 GPa after annealing at 300 °C. The growth of ZnO grains in Ti-ZnO/MoS₂ coatings were different from the other coatings based on the Raman analysis, and Al-doped coating showed better fracture toughness and binding forces from indentation and scratch testing. These results suggest that the respective underlying mechanisms of these metals in ZnO/MoS₂ coatings were different. As a result, this study shows that select metals could improve the different properties of metal-ZnO/MoS₂ coating by utilizing different mechanisms. Formation of ZnS might account for the synergistic lubrication of ZnO and MoS₂ co-doped coatings, and ZnO/MoS₂ coatings had moisture resistance because of no sulfate radical appeared by XPS analysis. Therefore, metal-ZnO/MoS₂ will be potential lubrication coatings to be widely used under natural ambient conditions.

In this study, we aim to minimize light loss and achieve high power conversion efficiencies (PCE) in perovskite solar cells (PSCs) by employing a spectral conversion film component with antireflection properties. In our scheme, NaYF₄:Tm, Yb, and Gd luminescent nanorod/silica nanosphere-based thin films are applied on CH₃NH₃PbI₃ PSCs to improve the device efficiency. The film was fabricated by spin coating an aged silica sol containing NaYF₄:Tm, Yb, and Gd luminescent nanorods. The size and the spectral conversion properties of the NaYF₄:Tm, Yb, and Gd luminescent nanorods were controlled by tuning the Gd³⁺ ion concentration. The microstructure and the transmittance properties of the thin film were controlled by changing the concentration of NaYF₄:Tm, Yb, and Gd luminescent nanorod in silica sol. The thin films have excellent spectral conversion properties while exhibiting a maximum transmittance. The photovoltaic performance of PSCs with NaYF₄:Tm, Yb, and Gd luminescent nanorod/silica nanosphere-based thin films was systematically investigated. The light transmittance was optimized to 95.1% on a cleaned glass substrate, which resulted in an average increase of about 3.0% across the broadband range of 400–800 nm. The optimized films widen the spectrum of light absorbed by conventional PSC cells and reduce reflections across a broad range, enhancing the photovoltaic performance of PSCs. As a result, the PCE of the PSC increased from 14.51% for the reference device without a thin film to 15.67% for the PSC device with an optimized thin film. This study presents a comprehensive solution to the problem of Fresnel reflection and spectral response mismatch of the PSCs, which provides new ideas for the light management of PSCs.

The tribological properties of metal-CuS/MoS2 composite coatings were improved by selecting the metal materials and optimizing the heat treatment process. The composite coatings were prepared by magnetron cosputtering of copper or aluminum metals, CuS, and MoS2. Then, the prepared Cu-CuS/MoS2 and Al-CuS/MoS2 were subjected to vacuum heat treatment at 220, 320, and 420 °C. The structure and tribological properties of the composite coatings were analyzed by scanning electron microscope, energy spectrum, x-ray diffraction, Raman spectrum, and multifunction friction tester. The results showed an island-like growth and a dense noncylindrical cross-sectional morphology of the metal-CuS/MoS2 composite coating. Metal- and CuS-doped MoS2 solid solution is a practical component in composite coatings. The wear scar of the composite coatings showed different color layers at different annealing temperatures due to composition deviation. After heat treatment at 320 °C, the friction coefficient of Cu-CuS/MoS2 coating was reduced to a minimum of 0.08. After heat treatment at 420 °C, the Al-CuS/MoS2 coating showed three different color layers of wear scar, and good tribological properties were obtained. The friction coefficient of the Al-CuS/MoS2 coating was as low as 0.06, and the adhesion of the Al-CuS/MoS2 coating was expressed in the HF1 level. The results show that the vacuum heat treatment can stimulate the action of CuS by forming a solid solution with MoS2, complementing the missing S atom during the sputtering deposition of MoS2 and improving the lubrication of the composite coating. In addition, although the action mechanisms are different, Cu and Al doping are all conducive to obtaining composite coatings with better tribological properties.

Bi₂Te₃-based alloys are representatively commercialized thermoelectric materials for refrigeration and power generation. Refrigeration mainly utilizes thermoelectric properties near room temperature, while the power generation temperature is relatively high. However, it is difficult for bismuth telluride to maintain good thermoelectric properties throughout the entire temperature range of 300–500 K. Herein, a series of Bi_xSb_2−xTe₃ alloys with different Bi contents were prepared by a simple preparation method and systematically investigated, and their best application temperature range was found. The Bi content can modulate carrier concentration and band gap, and the maximum dimensionless figure of merit (ZT) value of Bi_xSb_2−xTe₃ can be achieved in the corresponding application temperature range. The maximum ZT of Bi_0.3Sb_1.7Te₃ with a Bi content equal to 0.3 reaches 1.14 at 400 K, and the average ZT is 1.06 in the range of 300–500 K, which is suitable for both power generation and refrigeration. Therefore, power generation technologies with higher application temperatures should be selected from Bi_xSb_2−xTe₃ materials with Bi content less than 0.3, and refrigeration technologies with lower application temperatures should be selected with Bi content greater than 0.3. This work provides experimental guidance for finding the composition of Bi₂Te₃-based alloys in scientific research and practical applications.