Tri-Branched Dithienothiophene TPA Chromophore and Nano-Fabrication by the Two-Photon Photopolymerization
Ran Hee Kim, Won Jin Kim, Shin Wook Yi, Hong Jin Kong and Kwang-Sup Lee
We have prepared and characterized a novel tri-branched two-photon absorbing chromophore tris-(4-dithieno[3,2-b;2’,3’-d]thiophen-2ylphenyl)-amine. TPA chromophore, HW-1 has UV-vis absorbance at 421 nm (maximum) and fluorescence emission at 459 nm (maximum) upon excitation at abs. maximum. As we increase the solvent polarity from toluene, THF to DMF, positive solvatochromism in fluorescence emission is observed 459, 464, 502 nm respectively. This implies extensive intramolecular charge transfer occur upon excitation leading to high TPA activity. Using this TPA chromophore as photosensitizer, 3D nanopatterns were successfully fabricated by two-photon photopolymerization.