Using Layer-by-Layer Self-Assembly in the Fabrication of Thin Films

Abstract

Aims: The LBL technique is leveraged in this study to perform thin film fabrication using (diallyl dimethylammonium chloride) (PDDA) and copper phthalocyanine-tetrasulfonic acid (CuTsPc). The deposition of PPDA/CuTsPc films over a glass substrate through alternate adsorption is studied in this research. Both manual and automated methods are examined to evaluate the efficiency of the LBL technique. Study Design:  Analysis. Place and Duration of Study: Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology-Bombay (IIT Bombay), between July 2019 and December 2019. Methodology: A clean glass substrate is used to perform the Layer by Layer assembly technique for fabricating three thin films of PDDA/CuTsPc. The first sample is prepared manually by immersing the glass substrate in an aqueous solution of polycation for eight minutes, which is followed by washing in deionized water and drying using nitrogen gas. This process is repeated until five bilayers are formed. UV-Vis spectroscopic measurements are used to analyze the absorbance trends. For the second sample, the same process is repeated but with an automated apparatus. An aqueous polyanion solution and an automated apparatus is used for the third sample with the remaining steps being identical to that of the previous samples. Results: For manually prepared samples, UV-Vis absorption spectra of glass covered with about one to five bilayers of PDDA/CuTsPc for showed that the increase in peaks are directly proportional to increase in the number of bilayers. A similar linear behavior is seen for the samples prepared by automated fabrication. The linear growth of the samples is fairly alike for the monolayers of PDDA and CuTsPc. Conclusion: An orderly deposition process is observed upon performing Atomic Force Microscopy and UV-Vis spectroscopy. The research findings show a linear behavior in the absorbance curve, which demonstrates the fact that monolayers form at every stage of the film fabrication process. It is also observed that the materials were being absorbed at the same rate for both the automated and manual methods