Transition-metal complexes modified Covalent Organic Frameworks (TM-COFs) have potential wide applications in the fields of nano-electronics and nano-photoelectronics due to their unique crystal and electronic structures. It is important to control the electronic structure by tuning the TM-COFs composition from the atomic level with the aim of improving the optical, electrical, and photo-electrical properties. The key is to find simple and feasible methods. Based on previous research results, in this project, using both first-principles calculation and experimentation, we will prepare a variety of TM-COFs and then tune the electronic structure by employing chemical doping and physical surface treatment, with the aim of controlling the optical and photo-electrical properties. The influences of electrical and magnetic fields, as well as strain on the structures and properties, will be investigated. Doping strategies for substantially altering the spin-orbital coupling will be proposed for applications in the fields of spin-electronics and spin photo-electronics, from both theoretical and experimental aspects. Materials design, synthesis, device fabrication, property characterization, and mechanism investigation will be systematically performed in this project for the purpose of improving the structure and properties, exploring new physical phenomena, and developing new applications. This project will propose new research results on atom-thin two-dimensional (2D) semiconductors and shed light on other 2D materials, contributing to the application research of this kind of material in nano-devices.