Electrical contact materials are increasingly widely used, but the existing electric contact lubricants still have lots of room for improvement, such as anti-wear performance and lubrication life. Due to the excellent electrical and lubrication properties, graphene shows great potential in lubricating the sliding electrical contact interface, but there is a lack of relevant research. Some researchers have studied the lubrication performance of graphene between the gold-coated/TiN-coated friction pair at an ultra-low current. However, the lubrication performance of graphene on more widely used electrical contact materials such as copper and its alloys under larger and more commonly used current or voltage conditions has not been reported. In this paper, we study the lubrication performance of graphene in the copper and its alloys sliding electrical contact interface under usual parameters, which is explored through four aspects: different substrates—copper and brass, different test methods—constant voltage and constant current, different normal loads and durability test. The experiments demonstrate that graphene can significantly reduce the friction and wear on brass and copper under the above test methods and parameters, with low contact resistance at the same time. Our work is expected to provide a new lubricant for electrical contact materials and contribute to enriching the tribological theory of graphene.

Wide-bandgap (WB) mixed-halide perovskite solar cells (PSCs) play a crucial role in perovskite-based tandem solar cells (TSCs), enabling them to exceed the Shockley–Queisser limits of single-junction solar cells. Nonetheless, the lack of stability in WB perovskite films due to photoinduced phase segregation undermines the stability of WB PSCs and their TSCs, thus impeding the commercialization of perovskite-based TSCs. Many efforts have been made to suppress photoinduced phase segregation in WB perovskite films and significant progresses have been obtained. In this review, we elaborate the mechanisms behind photoinduced phase segregation and its impact on the photovoltaic performance and stability of devices. The importance role of advanced characterization techniques in confirming the photoinduced phase segregation are comprehensively summarized. Beyond that, the effective strategies to alleviate photoinduced phase segregation in WB mixed halide PSCs are systematically assessed. Finally, the prospects for developing highly efficient and stable WB PSCs in tandem application are also presented.