太陽光中紅外光波長範圍為780 nm至1 mm，而其中780 nm至1500 nm佔據了紅外光總能量的85%，這波段的光會使地球上的物質(例如:空氣、人體、建築物)分子振動而產生熱，因此如何不損耗額外的能源隔絕紅外光，且此隔絕元件又能不影響可見光穿透度，以達到作為智慧節能的綠建材，是一個值得探討的議題。
本篇論文利用膽固醇液晶模板技術搭配特殊製程，製作出具備縱向螺距梯度以及可同時反射左右圓偏振之高反射率寬頻帶紅外光子能隙元件，其反射率可達80%以上，光子能隙波段涵蓋800 nm至1500 nm，且仍保有可見光波段的穿透度，因此可作為智慧節能玻璃。在冬季的太陽光底下實際測量發現，與一般玻璃相比，此元件能有效降低密閉空間內的溫度約攝氏2至3度。未來，期望可將此膽固醇結構利用3D列印技術寫在玻璃窗上，做為真正的綠建材。

Infrared (IR) light from the sun spans from 780 nm to ~1 mm, and more than 85% of its energy lies between 800 nm to 1500 nm. IR reflectors or absorbers are very important as smart windows in eco-friendly buildings, because these devices can filter out IR light and control access of solar energy to regulate indoor temperature and maintain interior illumination. In this study, cholesteric liquid crystal (CLC) template technique was employed to fabricate a high-quality polymeric IR reflector.
The IR photonic bandgap (PBG) reflector was fabricated through the CLC polymer template (washing out/refilling) technique. The fabrication involved four stages, namely, the before-curing, after-curing, after-washing-out, and after-refilling stages. A CLC template cell with a broadband reflection was fabricated using weak UV light-induced longitudinal pitch gradient, which leads to the broadening of PBG. In addition, a highly reflective IR mirror was achieved by adopting a single-layer CLC template film with a double-spiral photonic structure. Finally, an IR reflector of CLC polymer was successfully produced. The device reflected more than 80% of the incoming IR light from 800 nm to 1500 nm and retained acceptable transmittance in the visible region. The thermal insulation test shows that a considerable amount of incident and unwanted heat could be reflected. Therefore, a significant amount of energy could be saved on cooling temperature up to 2–3 °C and maintain interior illumination. The structure proposed in this study might be written on windows by 3D printing technique in the future as eco-friendly building materials.

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