噴印成膜之環邊效應研究及其於顯示器光電元件之應用

Abstract

本論文利用液滴乾燥成膜後，自然形成邊界細高於中心位置之咖啡環現象，使突破噴印製程細線塗佈之限制，得到了更小尺度之微細線與及微結構，並應用於微光學元件上。論文前半部為咖啡環在微小尺度之影響因子探討，包含田口與及YFLOW模擬；後半部為結合咖啡環現象與噴墨塗佈技術之於光電元件開發，包含有機薄膜電晶體、微透鏡與及彩色濾光片。本論文利用穩健性田口工程實驗計畫法，尋找出影響咖啡環微細環邊之三個主要因子分別為「過濾與否、溶質濃度與及溫度」，而於進一步的最佳參數組合實驗後，我們得到2.49µm之超微細線寬；另外我們利用YFLOW模擬軟體研究咖啡環與界面表面張力、溶液擴散速率、溶劑蒸發等現象探討咖啡環形成機制，並最後以溶質濃度因子驗證模型，得到與田口工程一致趨勢的結果。進一步地，我們利用咖啡環現象結合噴墨塗佈技術，應用於有機半導體薄膜電晶體之縮小通道寬度設計，以提升電晶體輸出電流大小；同時我們也將噴墨技術結合咖啡環現象進行微透鏡製作，於此研究我們得到了高開口率、曲率可控制性之高品質微透鏡；最後我們也利用噴墨技術與咖啡環現象進行全噴印無光罩式之彩色濾光片陣列薄膜，並用咖啡環現象進一步形成長條溝槽之擋牆，藉由噴頭移動間距進而定義出等同之擋牆間距，我們得到可調變解析度之彩色濾光片面板，最後並達到67.8％NTSC之可商業化能力之7吋塑膠基版彩色濾光片。本論文期望能建立一套無光罩之全塗佈製程微光學光電元件之開發，以企圖達到軟性顯示器於可捲對捲之製造目標。

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.