| 摘要: | 本計畫欲開發含氧化物奈米結晶之有機/無機奈米複合材料。其中無機物質含量超過 35 Vol%，並可製作成高無機比之透明複合厚膜。目標厚度約為10um，透光率大於 98%，而折射率可由添加無機物前(環氧樹酯或壓克力樹酯約1.5) 提高到大於1.8。若用含硫樹酯(折射率約1.65)則甚至有可能將折射率提高至1.9 以上。高折射率無機/有機混成材料可能有許多應用。但是過去文獻中泰半以製作約數百奈米之薄膜為主，僅有很少人嚐試過製作超10 um 以上之厚度。若預備將此類材料用在透鏡陣列或LED 封裝等應用，就有必要超過10 um 厚度。要製作較折射率厚膜的最大困難，是在提高折射率的同時，又要能保持其透明性。要達到透明的第一個要件是有小於 10 奈米且分散良好的氧化物粒子。我們過取再此一方面已經很有進展。並且就高分散性的氧化鋯、氧化鋅奈米粒子作方法皆有專利。而且還在先期實驗中，確實將氧化鈦、氧化鋯等奈米粒子經過表面修飾後，與折射率為 1.5 之環氧樹酯複合成為大於10um 之透明厚膜。當氧化鈦含量達約40 wt%時候，做到折射率1.7 之複合材料，在氧化鋯達到約40 wt%時候，也有約1.6 之折射率。但是此一結果還未能理想。因為挼無特殊做法，不容易將無機含量提高。氧化物奈米粒子表面一定要經過有機分子修飾才有可能與樹酯混合。當粒子很小時，僅此表面修飾，既使不添加額外有機高分子，就已經使無機含量低於40 vol%。由而限制了無機物的含量。所以我們要設法改用較小的耦合劑，此部分將以自行設計合成矽烷為之。或者直接在粒子上進行寡聚物之接枝。有機分子修飾無機粒子，但是出了表面修飾外，最後還是要添加高分子才能成為混成樹酯。希望可以達到最高無機含量。另外，當複合材料中無機物量提高時，幾乎成為固體，必須有稀釋劑才能加工。當稀釋劑揮發時候，可能造成自組裝。此或許可以利用為特定結構厚膜的製作方法。值得進一步研究。又如高濃度的奈米粒子在高黏度流體中之動態應變，也需要由基本理論上試圖建立模型才能了解。我們若製作出高折射率透明厚膜，預備用壓印方法製作出表面菱鏡或透鏡等光學結構之微透鏡陣列。此一結構之設計，需要光學專家以模式先行計算。然後我們預計將此種材料試用到LED 封裝上，並且檢驗是否可以提高LED 之出光效率。The performance of optoelectronic devices such as FPD, LED and photonic circuits could be significantly improved if easy to process polymers with high transparency and high RI are available. One of the approaches to increase the RI of a polymer is to incorporate inorganic nanoparticles (NPs) having high RI. Among the choices are oxides such as ZnO, ZrO2, TiO2 or HfO2. For example, the external light extraction efficiency of LED is limited by the total reflection at the interface of the GaN/packaging interface, where a large RI mismatch exists. The light extraction efficiency of LED could be increased by 22% when the RI of the packaging epoxy was increased from 1.53 to 1.67 with the addition 10 % v/v (~26 wt %) of 20 nm TiO2 NPs[1]. In addition to LED, transparent composites with high RI also find applications in cases such as waveguide, photonic circuits, photochromic materials and, in particular, as transparent substrate or flexible functional layers for soft optoelectronic devices. It could also be useful in nonlinear optical devices, optical data storage, 3D photonic crystals via laser writing or microlens array via embossing. There has been many studies claiming to achieve high RI with O/I hybrid coating, but usually for thin film < 300 nm thickness, which may be enough for wave guide and similar applications, but is not sufficient for applications such as photonic crystal, holographic recording or high RI substrate. Specific Aims: In this project, we propose to study the preparation of transparent thick film of high RI nano-composites with the inorganic NPs, such as ZrO2, TiO2 and ZnO we have already mastered[2-5]. The composite should reach a RI higher than 1.9 if we select a sulfur containing resin, while remaining transparency at thickness larger than 10 μm, and should be curable at below 200oC. We will further investigate ways to make thick film with patterned optical features using techniques such as inkjet printing or hot (UV) embossing, and confirm the improvement on light extraction when applied to LED. Aside from the above targets, we will also like to take the opportunity to expend our NPs synthesis to HfO2, whose RI is even higher than TiO2, and explore the possibility of making high RI nanoparticle liquid (NPL), which is the most likely liquid for the immersion lithography processing of microelectronic beyond 45 nm line width. We will further extend the scope to low RI composite by incorporating NPs of microporous zeolite (RI~1.3), on which we had many experiences[6-8]. The availability of easy to process composites with both low and high RI will enable a much more freedom on the design of optical devices in the future. 研究期間 : 9808 ~ 9907 |
