Thermoelectric (TE) energy converters have attracted great interest due to their maintenance-free, long-life, and high-reliability properties. However, improving the output power of TE devices remains a huge challenge. In this work, a high-efficient photo-TE coupling generator based on cuprous iodide (CuI) film is proposed to increase the output power of TE devices. Here, CuI film was prepared by the successive ionic layer adsorption and reaction method. The influence of the photovoltaic (PV) effect on the TE output voltage of CuI film was investigated by an analysis of the experimental results. The results showed that the output voltage of the photo-TE coupling generator had a maximum increment of 83.47% at 343 K compared to the sum of TE and PV voltages. The increase in the output voltage was mainly because of the PV effect rather than the TE effect, while the photo-generated electrons also induce a considerable change in the TE figure of merit. Hence, the strategy proposed in this work might be a potential approach to further improve the output performance of other TE materials.

Substrate has an essential influence on the growth process of diamond grains and the quality of the diamond coating. In this paper, the diamond coatings on Co-cemented tungsten carbide (WC-Co) and silicon nitride (Si3N4) substrates were deposited by hot filament chemical vapor deposition (HFCVD) technique to study the effect of growth process on adhesive strength of coating. The WC-Co and Si3N4 substrates were treated by etching and polishing process, respectively. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the diamond coatings. Furthermore, the adhesive strength and tribological properties of the as-deposited diamond coatings were evaluated by indentation tests and dry sliding tests. The results showed that the diamond coating deposited on WC-Co had a considerable stronger adhesive strength and a higher friction coefficient than that on Si3N4, which may partly result from the flat surface morphologies of Si3N4 substrate that was due to no etching pretreatment. Thereafter, a novel etching method for Si3N4 surfaces by hydrofluoric acid (HF) was proposed to roughen the surface, and a new diamond coating with enhanced adhesive strength was fabricated on Si3N4. Hence, for the hard substrate, etching the surface, rather than polishing the surface, played an importance role on improving the adhesion strength of diamond coating.