Hybrid Interface Between Monolayer TMDCs and Covalent Organic Framework

The field of Covalent Organic Frameworks (COFs) has rapidly evolved over the past two decades, with numerous studies focusing on exploring the structural diversity, properties, and applications of these porous organic materials. COFs offer several advantages such as ordered structure, high chemical stability, and tunable optical and electrical properties. These advantages can be favorably utilized if combined with inorganic semiconductors with complementary properties. In particular, the ordered nature of COFs provides a unique knob (axes orientation dependence) to control the charge transfer process at the hybrid interface.<br/>In this work, we investigate hybrid heterointerfaces between several imine-based COFs including 1,3,5-tris (4-aminophenyl) benzene - benzaldehyde (TAPB-PDA) COF and thiophene doped TAPB-PDA with four TMDC monolayers: tungsten diselenide (WSe₂), molybdenum diselenide (MoSe₂), tungsten disulfide (WS₂), and molybdenum disulfide (MoS₂). Optical spectroscopy reveals formation of a charge transfer state at the heterointerface of TAPB-PDA and WSe₂ well below the bandgap of either individual material system. This suggests a type-II bandgap alignment resulting in a charge transfer exciton at the hybrid interface. The results from our investigation on orientation dependence formation dynamics of the charge transfer exciton along with UPS, PXRD, UV-Vis, CVs of the hybrid interface will be presented. Hybrid states generated at the interface between crystalline COFs and 2D materials represents an exciting opportunity to tune optoelectronic properties for a variety of applications from energy conversion to beyond-CMOS devices.