Der-Jang Liaw
National Taiwan University of Science and Technology, Taiwan
Title: Novel Functional Polymeric Nanomaterials : Synthesis, Optoelectronic, Selective Dispersion of SWNTs and Photovoltaics Applications
Biography
Biography: Der-Jang Liaw
Abstract
Novel nanomaterials such as polyimides (PIs), polyamides (PAs), conjugated polymers and polynorbornenes (PNBs) were successfully prepared from various polymerization techniques including low temperature polycondensation, Suzuki coupling and ring-opening metathesis polymerization (ROMP). PIs derived from different architecture designs revealed unique physical-mechanical, electrical and chemical properties. In addition, the PIs films also exhibited high thermal stability (Tg >300oC), transparency above 90% in visible light region (400-700 nm) and flexibility which are important for optoelectronic applications. PAs with the pyridine moiety displayed good film forming abilities, flexibility, high thermal resistance and yellow emission at 552 nm due to excimer generated by protonation. Conjugated polymers were used for single-walled carbon nanotube (SWCNT) wrapping to separate metallic and semiconducting nanotubes. Their chiralities such as (6,5), (9,5) or (8,7) were identified by photoluminescence-excitation (PLE) maps as well as UV/vis/NIR absorption spectra. Polytriarylamines- or poly(triarylamine-fluorene)-based conjugated polymers with water/alcohol solubility were applied for the hole-transporting materials of solar cells including perovskite solar cells and organic photovoltaics (OPVs). The conjugated polymers and PNBs containing hexa-peri-hexabenzocoronene (nanographene) were well dispersed in cyclohexylpyrrolidone (CHP) by bath sonication and possessed exfoliation emission in PLE maps. PNBs synthesized via ROMP showed excellent transparency (90%) and high thermal stability (Tgs >160oC). Triarylamine-containing polymers had electrochromic properties and capacity for multiple colour change reversibilities. The triphenylamine-alt-fluorene conjugated copolymer with hexaphenylbenzene (HPB) and pyrene as asymmetrical pendant groups showed the strong near-infrared (NIR) electrochromic absorbance attributed to intervalence charge transfer by the incorporation of the HPB moiety. These polymeric materials had high organo-solubility in common solvents and as a result can be used for solar cells, organic field effect transistors, polymer memories, and smart windows applications.
