Organic photovoltaic semiconductors have made significant progress and have promising application prospects after decades of development. When compared with traditional semiconductors, the solution method for preparing photovoltaic semiconductors shows the advantages of low cost and convenient preparation. However, because of the extremely poor solubility of the polymers used to prepare semiconductors, toxic solvents must be used when using the solution method, which has significant negative effects on the environment and operators and severely limits its development prospects. Organic nanoparticles (NPs), on the other hand, can avoid these issues. Because NPs are typically water or alcohol-based, no toxic solvents are used. Furthermore, NPs have been used in organic solar cells, hydrogen catalysis, organic light-emitting diodes, and other fields after nearly two decades of development, and their preparation methods have been developed. We describe the preparation, optimization, and application of NPs in photovoltaic semiconductors in this review.

Due to the characteristics of lower material waste, higher crystallinity, roll-to-roll compatibility, and high-throughput continuous processing, blade-coating has been widely applied in the preparation of large-area organic solar cells. In this paper, the technique of blade-coating is introduced, including the effects of blading speed, substrate temperature, and other technological innovations during the process of blade-coating. Besides, the recent progress of blade-coating in organic solar cells is summarized and the active layer prepared by a blade-coating method is introduced in detail, including materials, processing methods, solvents, and additives. The interface layer and electrodes prepared by the blade-coating method are also discussed. Finally, some perspectives on the blade-coating method are proposed. In the foreseeable future, blade-coating will become the core of batch production of large-area organic solar cells, so as to make organic solar cells more competitive.

Diamond-like carbon (DLC) and graphite-like carbon (GLC) coatings have good prospects for improving the surface properties of engine parts. However, further understanding is needed on the effect of working conditions on tribological behaviors. In this study, GLC and two types of DLC coatings were deposited on GCr15 substrate for investigation. The friction and wear properties of self-mated and steel-mated pairs were evaluated. Two temperatures (25 and 90 ℃), three lubrication conditions (base oil, molybdenum dithiocarbamate (MoDTC)-containing oil, MoDTC+zinc dialkyldithiophosphate (ZDDP)-containing oil), and high Hertz contact stress (2.41 GPa) were applied in the experiments. The results showed that high temperature promoted the effect of ZDDP on steel-mated pairs, but increased wear under base oil lubrication. The increased wear for steel-mated pairs lubricated by MoDTC-containing oil was due to abrasive wear probably caused by MoO₃ and β-FeMoO₄. It was also found that in most cases, the tribological properties of self-mated pairs were better than those of steel-mated pairs.