The design and synthesis of high-performance organic semiconductors are important for the development of future organic optoelectronics. Recently, we have made efforts to develop new organic semiconductors based on two dimensional fused acene frameworks. Our group developed the facile synthetic routes to chemically modify the K-region of pyrene and produce 4,5,9,10-pyrene diimide (PyDI) derivatives. The PyDI represents a new family of multifunctional aromatic diimides that exhibit both high electron mobility and excellent light-emitting properties. We have made systematic efforts to expand the library of PyDI derivatives and explore their applications various organic electronic devices, including organic field effect transistors (OFETs) and organic memory devices. Recently, we demonstrated that PyDI derivatives can be used as effective cathode interfacial materials for organic solar cells (OSCs), which are capable of boosting the device performances by broadening the absorption, forming ohmic contact at the interface as well as facilitating electron collection. Recent, we report the design of photostable singlet fission (SF) materials based on the flavanthrene structure, which has an N-doped two dimensional angular fused acene framework. Compared with linear acenes, two-dimensional angular fused acenes have more aromatic Clar's sextets, making them significantly more stable than linear acenes with only one sextet. Meanwhile, N-doping can raise the ionization potential of the system, making the molecular less susceptible to oxidization. We show that flavanthrene is a promising SF chromophore for photoenergy conversion applications, while a fine-tune of the intermolecular interaction is crucial for achieving high SF efficiency.