The study of ring edged effect in inkjet printing film forming and its application in optoelectronic devices

• Main Authors: Lu, Jhih-Ping, 呂志平
• Other Authors: Chen, Fang-Chung
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/38442601938941770536

博士 === 國立交通大學 === 光電工程學系 === 99 === This dissertation describes the application of the “coffee ring” phenomenon that occurs in the formation of droplet-evaporated films, where the edge height of the coffee ring is higher than that at the center, to break through the limitations of fine-line spreading during the inkjet printing (IJP) process and, thereby, allow the preparation of even smaller micrometer-scale fine lines and micro-structures for application in the development of micro-optoelectronics components. The first half of this dissertation describes the factors influencing the formation of micrometer-scale structures using the coffee ring effect, including Taguchi experiments and YFLOW simulations; the second half describes how the combination of coffee ring phenomena and IJP techniques can be used to prepare optoelectronic components, including organic thin film transistors, microlenses, and color filters. Steady Taguchi experimental engineering methods were employed in this study to determine the three major factors affecting the development of fine ring-edges: whether filtering was performed, the solute concentration, and the temperature. The optimal conditions provided a super-fine line-width. YFLOW simulation software was used to determine the effects of the interfacial tension, the dilution velocity of the solution, and the rate of solvent evaporation that influenced the mechanism of formation of the coffee ring structures. By justifying this model with solute concentration factors, the trends of the simulated results were consistent with those of the Taguchi engineering studies. Combining the coffee ring phenomenon with IJP, the current output of an organic thin film transistor was increased by narrowing its channel length; in addition, this combination allowed the production of high quality microlenses with high aperture ratios and highly controlled curvature; we also developed an all-IJP approach, without the need for masks, to produce thin-film color filter arrays by using the coffee ring, ultimately obtaining a commercializable six-inch plastic substrate color filter with an NTSC value of 67.8%. The results described in this dissertation are a step toward the development of micro-optical optoelectronic components using printing processes throughout, without masks, with the ultimate goal of producing flexible displays that can be fabricated using roll-to-roll techniques.