• 學位論文

螺旋超穎材料之負折射與旋光性之研究

Chiral metamaterials refer to metamaterials consisting of gyrotropic inclusions that do not have a superposable mirror image. Because of the extraordinary optical activity (OA) and circular dichroism (CD) phenomena, it has been suggested that chiral negative index meta- materials (chiral NIMs) can provide a new route for constructing a superlens that goes beyond the diffraction limit. The plasmonic-enhanced circular dichroism, on the other hand, has also been evaluated as a crucial key in bio-chemistry to boost the sensitivity of CD- spectroscopy to dissect complex biomolecules, such as proteins. In this regard, there has been an increasing interest in studying chiral metamaterials. In this thesis, we investigated, designed, and simulated the chiral metamaterials based on the intertwined gold helices, ded- icating to construct negative index materials and high transmission and large rotary power devices through finite-difference time domain (FDTD) method. By employing the effective parameter retrieval technique, a four-intertwined helix combined with metallic wire griddings that reached NIM was proposed. The NIM exhibited the maximum figure of merit (FOM, −Re{n}/Im{n}) of 0.5 under normal incidence at 24.72 THz for the LCP wave. Incorporat- ing the simulations with genetic algorithm (GA), we designed 4 polarization rotators with maximum rotary power 105.24 (0/λ)and extremely high transmittance (average above 80%) at the communication wavelength of 1.55 micrometer. These results show that helix-based devices serve as potential candidates for future optoelectronic applications.

• 學位論文

大面積有機光電元件的製程開發與分析

有機太陽能電池近年來受到各界矚目的主要原因為其可應用於大量生產的捲軸式製程低價製作於塑膠基板上，因此有機太陽能電池在價格上有很大的競爭力甚至在未來可望挑戰目前市佔率最高的矽晶太陽能電池。因此大面積捲軸式製程為有機太陽能電池未來必然的走向，此研究探討匹配於捲軸式製程之大面積刮刀塗佈技術在有機太陽電池製作之問題，目的是開發可適用於捲軸式製程製作之高效率大面機有積太陽電池製程方法。 我們首先探討刮刀製程之大面積塗佈問題，設定之元件結構為ITO/ Cs2CO3/P3HT:PCBM/PEDOT:PSS/Ag。然而在大面機刮塗製程中，常常會有表面缺陷的問題產生，我們發現使用共溶劑的方式可解決了大面積的塗佈製程中常會有表面缺陷的問題，同時我們利用小面積元件分析共溶劑對於元件太陽電池特性之影響，發現可利用兩種溶劑不同的沸點以及溶解度改善了主動層材料的垂直分布，進而改善了有機太陽電池之效率。 其次，我們探討適合於大面積反式結構電子選擇層之溶液製程。由於碳酸銫(Cs2CO3)具有易潮解的特性，對於元件壽命有很大的傷害。因此在大氣下穩定且具有高載子遷移率的材料氧化鋅(ZnO)近年來被廣泛的研究與使用，在此我們利用化學浴沉積法(Chemical Bath Deposition)來製備氧化鋅並成功的應用在有機太陽能電池上，並且也克服其他製備氧化鋅製程的缺點，製作出一表面平整、緻密且無孔洞的氧化鋅薄膜，最高效率可達4.61%。此方法未來更可應用於大面積捲軸式製程。 最後，由反式結構有機太陽電池研究，我們利用所觀察到的特殊I-V曲線開發出無須選擇元件即可獨立驅動之二維光偵測器結構。本研究裡我們成功製作出有機光偵測器陣列，並分析其特性。由於光偵測器在日常生活中已被廣泛應用，而有機光偵測器因其能夠製作在各種軟性基板上並可大面積化，因此深具發展潛力。

• 學位論文

實驗上觀測決定性合成表面電漿子漩渦

本論文使用有限差分時域法模擬透過幾何結構以及入射圓偏振光的旋向所決定的合成表面電漿子漩渦。我們以阿基米德螺旋為雛形，設計出六種結構，它們會產生不同的表面電漿子漩渦能量分布。此外，我們的解析解相當地符合數值模擬的結果。我們的設計可以自由地改變電漿子漩渦的能量分布，而且這個技術可能在光捕捉上會有有趣的應用。 在實驗方面，我們利用熱蒸鍍與聚焦離子束來製造元件。光學測量系統是用收集式近場光學掃描顯微鏡，這個系統包含商業的近場光學掃描顯微鏡與正向入射架構以及自己製作的沒有鍍金屬的探針。藉由比較實驗與模擬的結果，我們驗證了實驗的測量結果是表面電漿波場強而不是梯度場強。

• 學位論文

Hole mobility characterizations of DNA biopolymer and its application in organic optoelectronic devices

As deoxyribonucleic acid (DNA) has attracted increasing research attention, the unique biochemical properties and easy availability have become great advantages of making DNA competitive and widely used. Owing to the intrinsic hydrophilic property of DNA, extra procedures are required to modify the DNA molecules. In this work, various surfactants were used to modify the DNA molecules for compatibility in organic process. The detailed syntheses and characterizations of these DNA biopolymers are described in Chapter 2. Fouriertransform infrared spectroscopy (FTIR) spectra, ultraviolet-visible (UV-VIS) spectroscopy spectra, surface morphology, and thermal stability of DNA biopolymers were also measured. The electrical properties and charge transport behavior of these DNA biopolymers are major parameters for the design of DNA-based optoelectronic devices. We characterized the conductivities and hole mobilities of DNA biopolymers in Chapter 3. The I-V characterizations of these DNA-based biopolymers exhibited a positive correlation between the concentration of surfactant and material conductivity as the stoichiometric ratio of DNABTMA from 1:1 to 1:10. In the hole mobility measurement, a positive molecular weight dependence was found in DNA-CTMA with 2000 and 200 base pairs. Besides, the hole mobilities of the DNA biopolymers increased at temperature from 253 to 303 K. We observed that the mobility first exhibited a negative dependence on the applied fields and gradually increased with electric field (when E > 2105 V/cm) above 273 K. Gaussian disorder model (GDM) was utilized to describe the transport mechanisms of charges in these DNA biopolymers. Such characterization results are informative for the employment of DNA biopolymers in optoelectronic applications. Due to the metallic affinity of DNA molecules, we developed a phototriggered process to synthesize a DNA-nanoparticle biopolymer. Silver nanoparticles (Ag NPs) were formed via a photochemical synthesis using Irgacure-2959 ((1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-one)) (I-2959). I-2959 produced ketyl radicals upon UV irradiation and the radicals then functioned as reducing agents to reduce silver ions, leading to the formation of Ag NPs. These DNA-based biopolymers combined with Ag NPs were employed as functional layers in the color tunable organic light emitting devices (OLEDs). When incorporating such nanocomposite into OLEDs, a color tunable property was achieved by varying the UV radiation time in the formation process of nanoparticles. The hole mobility of the DNA-CTMA/Ag NP (deoxyribonucleic acid-cetyltrimethylammonium/silver nanoparticle) biopolymer was affected by the UV irradiation process, resulting in the shift of the recombination zone. We also applied the concept of negative electric field dependency of the biopolymer in the color tunable OLEDs by tuning the driving voltage. The materials formed by Ag NPs embedded in DNA-based biopolymer were proved to be able to provide a facile way to tune the hole mobility of DNA biopolymers, which are promising for the applications in various DNA-based optoelectronic devices. Furthermore, these DNA-based biopolymers combined with Ag NPs were also integrated into the memory devices. The device exhibited write-once read-many-times (WORM) memory behavior and nonvolatile property. Through tuning the Ag NPs content by external doping process in the DNA-based biopolymer film, the electronic devices are capable of exhibiting write-once read-many-times (WORM) memory effect, rewritable memory effect, and conductor behavior. These controllable electrical properties and nonvolatile electrical bistable switching effects of these devices can be attributed to hole trapping in the Ag NPs of the DNA-based biopolymer matrix. The operation cycles of the device with fairly good accuracy can be further achieved by improving the distribution of the Ag NPs under magnetic stirring. The demonstration of the DNA-CTMA-Ag NPs memory device implies the potential to use DNA-based biopolymer for high capacity and low-cost storage element in future electronics.

• 學位論文

脈衝於色散遞增光纖傳遞達大倍率頻譜壓縮

光脈衝頻譜壓縮可有效增加頻譜亮度，即有效提升訊雜比，因此有助於光譜學上的應用與發展。光脈衝在標準單模光纖之頻譜壓縮現象於1978年提出，並於1993年有明確的物理解釋，指出頻譜壓縮主要為自相位調變作用於負啁啾脈衝。 本論文頻譜壓縮系統為傳統絕熱系統光孤子脈衝壓縮的反向操作，並用一線性色散遞增光纖達成頻譜壓縮結果。由於在絕熱系統光孤子壓縮理論下，頻譜壓縮比受限於光纖條件，但本論文模擬分析顯示真實頻譜壓縮可以超越光纖條件限制。在實驗上，證實半高寬為112飛秒鎖模雷射脈衝頻譜壓縮比為28.6倍，並超越本實驗室光纖理想壓縮比22.5倍。 近年來，開始探討波形相關的頻譜壓縮可能性。本論文分析各種波形的頻譜壓縮可能性，模擬結果顯示正色散光纖雷射脈衝對比於雙曲正切與高斯脈衝，擁有較高頻譜壓縮比，並使用本實驗室架設之全正色散光纖雷射作為光源，於實驗上得到頻譜壓縮比高達45倍之結果。

• 學位論文

利用色散遞增光纖產生頻譜壓縮雙峰與特性分析

雷射光頻譜壓縮藉由能量在頻譜上的重新分佈，達到增加頻譜亮度，亦即頻譜訊雜比之目的，有助於提升飛秒雷射和超連續光頻譜的應用及發展性。本論文使用線性色散遞增光纖，透過絕熱系統下光孤子脈衝壓縮的反向操作達到頻譜壓縮。 然而，近年來有關頻譜壓縮的研究仍局限於頻譜上存在單一高峰的範疇。本論文成功地利用色散遞增光纖產生頻譜壓縮雙峰，且頻譜雙峰的特性，包括相對振幅及波長得以透過雷射源的平均功率、入射脈衝啁啾的條件調整並做分析。比對以飛秒鎖模脈衝為雷射源所量測到的實驗結果與透過非線性薛丁格方程式的數學模型所計算的數值模擬結果，兩者具有非常好的相似性。