| 학회 | 한국고분자학회 |
| 학술대회 | 2005년 봄 (04/14 ~ 04/15, 전경련회관) |
| 권호 | 30권 1호, p.477 |
| 발표분야 | 분자전자 부문위원회 |
| 제목 | Highly Efficient Two-photon Absorbing Fused Thiophene Derivatives |
| 초록 | Introduction There is a lot of efforts to seek highly efficient two-photon absorption (TPA) chromophores for photonic and bio-photonic applications such as up-converted fluorescence lasing, TPA optical power limiting, 3-D optical data storage, bio-imaging, photodynamic therapy, precision high 3-D micro-fabrication [1,2]. Some critical molecular design concepts have already been explored in efforts for establishing relationship between molecular structure and TPA activity [3-5]. The π-conjugated molecular systems particularly those with phenylenevinylene, phenylene-ethynylene, fluorene, and fused thiophene found to be good candidates. In this work, we report the synthesis of combined structure both dithienothiphene (DTT) and phenyleneethynylene (PE) units which has strong electron donating groups (D). Here DTT and PE units were selected as π-bridge centers between the electron donating end groups which can contribute to increase effective electron density and coplanarity along the chain. Results and Discussion The DTTPE-based chromophores (TP-DTTPE-TP, NBu2-DTTPE-NBu2) were synthesized by the coupling reaction from acethylene derivatives having electron donors and dibromo-subsitituted DTT derivatives. Photophysical properties including TPA cross-sections of the resulting chromophores are measured. Both chromophores show the UV-visible absorption peaks at the wavelength of near 440 nm making these chromophores ideal for TPA research even they have relatively long conjugated length. To evaluate the TPA cross-section (δ) of DTTPE-based chromophores, Ti:sapphire laser with 85-femtosecond (fs) pulse at a repetition rate of 82 MHz as a excitation source was employed. The maximum δ value of NBu2-DTTPE-NBu2 (δ=11,000 GM) increased by a factor of about 2 when comparing with the compound TP-DTTPE-TP (δ=5,500). This implies that the TPA activity strongly contribute to the electron donor strength of the end of molecules (N,N-dibuthyamine ＞ N,N-diphenylamine). The δ values obtained by the Z-scan method are almost matched with those of fluorescence measurements. In order to get micro-patterns by two-photon initiated polymerization, we performed lithographic microfabrication works. The chromophore was mixed with urethane acrylic ester-based resin (SCR-500, Japan Synthetic Rubber Company) in 0.1 wt%. After irradiation in this mixture under the computer control, the unpolymerized resin was washed away with ethanol. Then, the solidified patterns are remained on the glass substrate. By employing this technique we successfully fabricated various 2-D and 3-D patterns with nm-size resolution. References [1] S. Kawata, and H.-B. Sun, Adv. Polym. Sci., 170, 169 (2004). [2] B. H. Cumpston, et al., Nature, 398, 51 (1999) [3] M Albota, et al., Science, 281, 1653 (1998). [4] T.-C. Lin, et al., Chem. Mater., 157, 157 (2002) [5] O.-K. Kim, et al., Chem. Mater., 12, 284 (2000). |
| 저자 | 김주연1, 이광섭2, 박상후1, 양동률3 |
| 소속 | 1한남대, 2신소재 공학과, 3화공 정보 신소재 공학부 |
| 키워드 | fused thiophene; photocurable; two-photon absorption |
