1. Trihalide perovskite is very popular recently. The number of papers published in theoretical and experimental research has increased exponentially. In the latest issue of Science magazine, there are actually two experiments on halide perovskite, and there is also one in the upcoming issue of Science magazine (which can be seen in Science Express).
Perovskite originates from the most primitive oxide ABO3 structure, but in the new trihalide perovskite, people use Cl, I and F instead of oxygen. The A-site and B-site can also be replaced by many methods, and even chemical molecules with polarization properties can be added to the A-site. The latest feature of this series of materials is that they can be used as materials for new solar cell systems, and many scientific researches are focused on their photovoltaic characteristics. But it is also a kind of perovskite, so many properties of perovskite have not been studied clearly (I believe there will be results soon).
Needless to say, graphene is a super hot spot. Basically, every physics department with condensed matter experiments will have a special team to do this. Of course, I don't know much about the specific issues. You can refer to wiki.
graphene
3. Topological insulators, which are also super hot spots, lead to various new phenomena, such as the quantum abnormal Hall effect of news broadcast, and a popular science article written by a team led by Professor Xue Qikun of Tsinghua University. Of course, this topological insulator not only supports the topological insulator itself, but also supports many heterogeneous heterostructures based on topological insulators, such as Bi2Se3/NbSe2, and various new phenomena at the interface. Similarly, the physics department with condensed matter experiments will also have a team to grow topological insulators with MBE.