玻璃雙面微結構滾輪壓印製程與應用於光學元件研究

Abstract

玻璃材料光學性質佳，機械強度高且抗蝕性強，能製作高品質之光學元件。尤其將微米與奈米結構製作於玻璃光學元件表面，能減少反射或導光。在玻璃上製作微結構，常使用電子束微影或雷射加工等，昂貴且耗時；而微熱壓複製成型技術如微熱壓成型又有製程時間長，且為批次生產。為達到連續生產、快速量產、降低成本，本研究利用熱滾壓方式成型，先預熱玻璃，當溫度達至玻璃轉移溫度左右時，將基材與熱盤移至熱滾輪進行滾壓，並搭配下模具，達成雙面微結構複製。 本研究先利用光學模擬軟體Trace Pro找出增強光強度之雙面微結構組合，包括V-cut及微透鏡；結果顯示雙面平行V-cut之增光強度效果最好。接著，本研究設計組裝滾壓機台，鎳質滾輪模具與平板鎳質模具，分別置於玻璃基材上下方，升溫滾壓製作之雙面平行V-cut玻璃，測其光強度比無結構之玻璃高。本研究並以田口實驗設計L9表，探討雙面結構熱滾壓成型之接觸溫度(熱盤、滾輪)、非接觸溫度(紅外線)、滾輪壓力、移動速度之重要因子與最佳組合。結果顯示最重要因子為滾輪壓力與移動速度。以最佳參數所製造之雙面平行V-cut玻璃，其光強度較無結構玻璃多約20μW/cm2。 本研究又進一步製作適用於高溫熱壓玻璃之玻璃碳模具，以澆鑄方法製作呋喃模具，在惰性氣體環境下，高溫炭化成玻璃碳模具。實際應用於熱滾輪壓印之下模，利用玻璃碳模具之抗沾黏特性，使結構高度成果更佳且更為均勻。 本研究並將所製作之雙面平行V-cut玻璃應用於染料敏化太陽能電池之入光面，由於光強度提高，電池電流密度較無結構玻璃提高26 %，電池效率提高34 %。

Glass is the preferred material for quality optical devices due to its high refractive index and low color aberration. Glass also possesses high mechanical strength and chemical resistance. Surface with microstructures and sub-wavelength nanostructures futher enable light guiding or antireflection capabilities. Currently, most micro or nano structures on glass are manufactured by e-beam lithography or laser machining techniques which are expensive and time-consuming. Mold replicating process such as micro/nano hot embossing has disadvantages of discontinuous process and long cycle time. In this research, for continuous and fast production, hot rolling method for glass substrate was developed. The glass was pre-heated to glass transition temperature (Tg) before it was embossed by roller and plane molds for dual-side microstructures. This research consists of three major parts. First, Trace Pro software was used to find out lumininous intensity of glass with different combination of v-cuts and micro-lens in surfaces. The result showed that the best module was glass with double parallel v-cut structures. This research also design an implement heating and hot rolling facility. Roller and plane Ni-molds with v-cut structures were used to emboss heated glass. The measured lumininous intensities from glass with microstructure were higher than that from bare glass. Then, Taguchi method L9 was used to investigate the significance of processing factors including speed, pressure, infrared temperature, and temperature of roller and hot plate. The results showed that speed and pressure were more important than others. Moreover, glass with dual-side v-cut microstructures was the best combination of processing parameters fabricated by rolling embossing. The lumininous intensity of the glass was 20μW/cm2 higher than that from bare glass. In the second parts, a simple and novel method to fabricate high-temperature resistant glassy-like carbon (GC) mold with microstrutures was proposed and studied. Furan precusor was produced by casting, then GC mold was obtained after carbonization process in the inert environment. Because of the anti-adhesive property of GC, the microstructures produced by the GC mold in rolling embossing was better and more uniform than that from Ni mold. In the last part, the glass with parallel v-cut microstructures on both sides was used as the top surface of dye-sensitized solar cell. The current density and efficiency of solar cell were 26% and 34.2%, higher than that from similar solar cell but with bare glass as the top surface.