Micron and submicron patterning of dicyanopyrazine-linked porphyrin molecules using micro-contact printing and Langmuir-Blodgett assembly.
We describe a method to conveniently fabricate micron- and submicron-sized patterns of well-ordered and densely-packed dicyanopyrazine-linked porphyrin (4-TDCPP) molecules by using micro-contact printing (micro-CP) in conjunction with Langmuir-Blodgett (LB) deposition. SEM and AFM images reveal that the sizes and shapes of the 4-TDCPP patterns are well-matched with the geometric features of the polydimethylsiloxane (PDMS) stamps used for micro-CP. Fluorescence images show strong, red emission from the 4-TDCPP patterns. However, the thicknesses of the 4-TDCPP patterns transferred onto a silicon substrate by micro-CP are not the same, even though the same amount of 4-TDCPP layers are deposited on the surface of PDMS stamps in the LB process. The thicknesses of the 10 microm line, 2 microm dot and 300 nm line patterns of 10-layered 4-TDCPP molecules are 34.6, 26.7 and 5.9 nm, respectively. These differences may be due to variations in adhesion forces between the silicon substrate and 4-TDCPP on PDMS stamps having different size patterns. Larger patterns have greater contact areas compared to smaller patterns. This phenomenon can cause stronger adhesion forces, resulting in greater pattern thickness.
Department of Fiber and Polymer Engineering and Institute of Nano Science and Technology, Hanyang University, 17 Haengdang-Dong, Seongdong-Gu, Seoul 133-791, Korea.
Jaepil
J
Cho
Heejoon
H
Ahn