The photonic and electronic properties of organic semiconductors are fundamentally different from their inorganic counterparts resulted from the weak intermolecular interaction and the highly localized Frenkel excitons. Our studies on organic nanomaterials demonstrated that not only can the wide panel of physical properties provided by organic compounds be fully exploited, but the properties can also be modulated by the changing the structures. These results extended the research on nanomaterials from metal and inorganic semiconductors to the organic compounds and showed different size-dependent characteristics of organic nanostructures. We investigated the interactions that affect the way molecular components aggregate into particularly shaped nanostructures and developed several general methods to control the self-assembling growth kinetics of organic nanostructures. These efforts open effective strategies for constructing organic nanostructures with well-controlled sizes, shapes and therefore functions, making them a novel class of nanomaterials attracting world-wide research interest.
i. Function-guided Design and Construction of Low-dimensional Organic Crystal Materials and Devices
Excellent optoelectronic performances of organic functional nanomaterials not only depend on the molecules itself, but also its composition and arrangement. Therefore, it is of great significance to develop controllable and stable preparation methods to obtain crystalline, monodisperse organic nanostructures with specific morphology (Figure 1). On the controllable construction of organic nanostuctures, we have been devoting to the exploration of the molecule self-assembly processes. The quasi-equilibrium process and nucleation-growth kinetics were systematically investigated.
Figure 1 Organic Micor/Nano-structures with different morphologies
ii. Performances and Applications of Organic Optofunctional Materials
The performances of organic optofunctional materials depend upon photophysical and photochemical processes heavily, such as exciton generation, separation, recombination, conversion, energy/charge transfer. We have found the strong coupling effect in organic condensates results in a new eigenstate, exciton polaritons (EPs), which plays an important role in the building of high-performance photonic devices. Moreover, the entanglements of EPs with surface plasmon polaritons(SPPs) bring new quantum effects at organic/metal interfaces, which can be utilized to solve a number of difficult problems in photonic circuits. On the basis of the breakthroughs in fundamental research, we have achieved various photonic components and prototype integrated devices, laying a good foundation for the future information technology.