Organic Three-dimensional π-Conjugated System: Construction And Application In Optoelectronics

The thesis focuses on the systhesis and characterization of three-dimensional congjugated molecules. These molecules have been applied in OLED, cage molecules which can be used in chemosensor, and supramolecular polymer with optoelectronic properties.In the first part, four three-dimensionally architectured molecules with spiro-annulated structural features were facilely developed. They can form uniform and amorphous films via spin-coating due to their rigid three-dimensional architecture. The PL spectra of all molecules exhibit excellent thermal stability upon air annealing. Their blue color integrity remained after continuous annealing for 12 h at 200 oC in the air. OLED fabrication reveals that all 3D molecules exhibit pure blue EL performance and good color integrity at different operating voltages. For the two-layer structure of ITO/PEDOT/EL/TPBI/Ba/Al, the maximum luminous efficiency and external quantum efficiency has been achieved at 3.4 cd·A-1 and 2.9%, respectively.In the second part, a readily modifiable structure with C3 symmetry was developed to quantitatively build a series of 3D shape-persistent fluorescent nanocages via dynamic covalent chemistry. The dynamic formation processes of the nanocages, directed by multivalent effect, were also observed by in situ 1H NMR spectroscopy. Meanwhile, through simply adjusting the side chains, we successfully achieved different surface morphologies of the nanocages and control of their surface distribution behavior.In the third part, we focus on the supramolecular polymeric nanowire constructed by a 3D shape-persistent monomer. We found that the rigid 3D hexaacid can form one-dimensional supramolecular polymer, either on surface or in solution phase. The optical, electron and atomic force microscopies indicate the morphologies of supramolecular polymer and their advanced structures, and diffraction and optical spectroscopies confirmed the model depicted as multiple H-bonding forming long axis and lateral weak interaction leading to short axis. For these nanowires form by H-bonding, theπ-πinteraction amongπ-conjugated chromophores are successfully prevented, and hence, high solid quantum efficiency (22%) has been achieved, which provides us a pathway to fabricate optoelectronic devices using these highly fluorescent nanofibers.In conclusion, the designed C3 symmetrical 3Dπ-conjugated system is different from common planarπ-conjugated molecules, especially in charge carriers transporting, aggregation state and semiconducting properties. Their advantages have been applied in the corresponding field and further modification and different synthetic approaches lead to other novel materials, such as microporous materials.