液晶-聚合物混合材料是一個相當具有應用潛力之複合式材料，因為這個複合式材料同時擁有兩種不同的狀態固相與液相，而且也同時包含均向性(高分子或單體)與非均向性(液晶)物質，眾多液晶顆粒無序且均勻的分布於單體或高分子中，所以過去吸引非常多科學家進行基礎研究與發展光電應用元件，例如可調控式光開關、光柵、雷射等。
因此，本論文著重於研究液晶顆粒無序且均勻的分布於單體或高分子中，其液晶顆粒的大小，會讓其光電特性有很大的不同，為了釐清背後的機制，因此，本論文主要分為三個研究的主題，第一部分是研究PDLC加以不同頻率的交流電時其奇特的光電特性。由於當加以交流電頻率>10 kHz時，樣品會有加熱的現象，因此第二部分就單獨的對PDLC加熱來測量其光電特性。由於前兩部分都是探討顆粒大小對光電特性的影響，因此第三部分乃改變其量測波長，來了解對PDLC光電特性有何影響。
實驗結果發現，傳統的米式散射理論無法完整解釋大顆粒PDLC之光電特性。因此本論文引入微透鏡概念，將大顆粒PDLC視為微透鏡，此微透鏡可理想化為一個半圓的形狀，利用造鏡者公式，先計算出其焦距，再利用散射光與光接收器之面積比值來計算其理論穿透率，利用此計算方式，搭配之前本實驗室所發現的大顆粒PDLC因電流體動力(electrohydrodynamics – EHD)效應之動態散射機制，可對大顆粒PDLC加以不同頻率交流電壓、不同溫度亦或改變量測波長之實驗結果加以完整解釋。最後，本論文利用大顆粒PDLC之微透鏡概念，開發出操作電壓比傳統PDLC還要低的開關元件，且其具有可逆性與重複性。

The thesis mainly investigates the disorderly and uniformly distributed LC particles in monomers or polymers. The size of the LC particles is determinative of their electro-optical (EO) characteristics. To methodically and qualitatively explore the peculiar EO characteristics of the LC particles, the investigation in this thesis is divided into three parts. The first part is to measure the abnormal EO characteristics of polymer-dispersed liquid crystal (PDLC) by applying AC voltage with various frequencies. Since the sample will be heated when the frequency of the AC voltage is higher than 10 kHz, the second part is to measure the thermal dependent EO characteristics of the PDLC by direct heating. The discussion in the first two parts are about the effect of particle size in PDLC on the EO characteristics. In the third part, the wavelength of the probe beam incident in the PDLC for measurement is varied to realize the relation between the wavelength of the probe beam and the EO characteristics of the PDLC.

Experimental results show that the Mie scattering theory cannot fully explain the EO characteristics of the large-particle PDLC. Therefore, the microlens theory is introduced in this thesis. Assume the large-particle PDLC as a microlens with a perfectly semispherical shape, the lens maker’s formula is adopted to calculate the focal length, and then the area ratio of the scattering light and detector is also considered to calculate the transmittance. By using this calculation method and the theory of dynamics light scattering by the electrohydrodynamics (EHD) effect in large-particle PDLCs, the transmitted features of the large-particle PDLC operated at AC voltage with different frequencies, different temperatures, or measured by the probe beam with different wavelengths can be completely explained. Finally, the large-particle PDLC introduced in this thesis is employed to develop tunable light valve devices with lower operating voltage compared to the traditional PDLC. Furthermore, the light valve device exhibits reversibility and repeatability.

1. C. H. An, J. Yang, Y. E. Lee, C. H. Kim, E. Nam, D. Jung, M. Ho. Cho, and H. Kim, “A Triple-Layered Microcavity Structure for Electrophoretic Image Display,” IEEE Trans. On Electron Device 58(4), 1116–1120 (2011).
2. D. W. Leeand and J. W. Shiu, “Writable Cholesteric Liquid Crystal Display and the Algorithm Used to Detect Its Image,” J. Display Technol. 5(6), 172–177 (2009).
3. B. Y. Lee and J. H. Lee, “Printable flexible cholesteric capsule display with a fine resolution of RGB subpixels,” Curr. Appl. Phys. 11(6), 1389–1393 (2011).
4. J. L. Fergason, “Encapsulated liquid crystal and method,” US Patent, 4435047 (1984).
5. D. Churchill and J. V. Cartmell. “Radiation sensitive display device containing encapsulated cholesteric liquid crystals,” US Patent, 3578844 (1971).
6. J. L. Fergason, “Encapsulated liquid crystal and method,” US Patent, 4435047 (1984).
7. O. V. Yaroshchuk and L. O. Dolgov, “Electro-optics and structure of polymer dispersed liquid crystals doped with nanoparticles of inorganic materials,” Opt. Mater. 29(8), 1097–1102 (2007).
8. O. V. Yaroshchuk, L. O. Dolgov, and A. D. Kiselev, “Electro-optics and structural peculiarities of liquid crystal-nanoparticle-polymer composites,” Phys. Rev. E. 72(5), 051715 (2005).
9. A. Masutani, T. Roberts, B. Schuller, N. Hollfelder, P. Kilickiran, and G. Nelles, “Nanoparticle Embedded Polymer Dispersed Liquid Crystal for Paper-like Display,” J. Soc. Inf. Display 16(1), 137–141 (2008).
10. A. Hinojosa and S. C. Sharma, “Effects of gold nanoparticles on electro-optical properties of a polymer-dispersed liquid crystal,” Appl. Phys. Lett. 97(8), 081114 (2010).
11. A. V. Sadovoy and V. F. Nazvanov, “Study of the electro-optical response of polymer dispersed liquid crystal doped with multi-wall carbon nanotubes,” SPIE 616407-1–616407-4, (2006).
12. S. Chandrasekhar, Liquid Crystal (Cambridge University Press, New York, 1992).
13. I. C. Khoo, Liquid Crystals: Physical Properties and Nonlinear Optical Phenomena (John Wiley & Sons, New York, 1995).
14. S. Zumer and J. W Doane, “Light scattering from a small nematic droplet”, Phys. Rev. A. 34(4), 3373–3386 (1986).
15. J. W. Caruthers, “On Rayleigh and Mie scattering,” ASA. 14(1), 070001 (2011).
16. J. Q. Zhao and Y. Q. Hu, “Bridging technique for calculating the extinction,” Appl. Opt. 42(24), 4937–4945 (2003).
17. M. I. Barnik, L. M. Blinov, M. F. Grebenkin, and A. N. Trufanov, “Dielectric Regime of Electrohydrodynamic Instability in Nematic Liquid Crystals,” Mol. Cryst. Liq. Cryst. 37(1), 47–56 (1976).
18. M. I. Barnil, L. M. Blinov, and S. A. Pikin, “Instability mechanism in the nematic and isotropic phases of liquid crystals with positive dielectric anisotropy,” Sov. Phys. JETP 45(2), 756–761 (1977).
19. S. A. Pikin, Structural Transformation in Liquid Crystals (Gordon & Breach, New York, 1991).
20. W. Helfrich, “Conduction-induced alignment of nematic liquid crystals: basic model and stability considerations,” J. Chem. Phys. 51(9), 4092–4105 (1969).
21. R. Williams, “Domains in Liquid Crystals,” J. Chem. Phys. 39(2), 384–388 (1963).
22. E. F. Carr, “Domains Due to Magnetic Fields in Bulk Samples of a Nematic Liquid Crystal,” Mol. Cryst. Liq. Cryst. 34(7), 159–164 (1977).
23. G. E. Zvereva, and A. P. Kapustin “in Primeneniye ultraakustiki kissledovaniyu veshchestva,” (Application of Ultraacustics to Investigation of Substances), Moscow 15, 69–? (1961).
24. A. N. Trufanov, L. M. Blinov, and M. I. Barnik, “New type of high-frequency electrohydrodynamic instability in nematic liquid crystals,” Sov. Phys. JETP 51(2), 314–319 (1980).
25. S. Pikin, V. Chigrinov, “New type of high-frequency instability in nematic liquid crystals,” Sov. Phys. JETP 51(1), 123–125 (1980).
26. P. G. de Gennes and J. Prost, The Physics of Liquid Crystals (Clarendon Press, New York, 1993).
27. D.-K. Yang and S. T. Wu, Fundamental of liquid crystal devices (Wiley, 2006).
28. S. Chandrasekhar, Liquid Crystal (Cambridge University Press, New York, 1992).
29. B. Bahadur, Liquid Crystals-Application and Uses Vol.1, (World Scientific Publishing, Singapore, 1990).
30. Eds. H. –S. Kitzerow and Ch. Bahr, Chirality in Liquid Crystals (Springer, New York, 2001).
31. S. Zumer and J. W Doane, “Light scattering from a small nematic droplet”, Phys. Rev. A. 34(4), 3373-3386 (1986).
32. A. N. Trufanov, L. M. Blinov, and M. I. Barnik, “New type of high-frequency electrohydrodynamic instability in nematic liquid crystals,” Sov. Phys. JETP 51(2), 314–319 (1980).
33. S. Pikin and V. Chigrinov, “New type of high-frequency instability in nematic liquid crystals,” Sov. Phys. JETP 51(1), 123–125 (1980).
34. P. G. d. Gennes, “Calcul de la distorsion d'une structure cholesterique par un champ magnetique,” Solid State Commun. 6(3), 163165 (1968).
35. 陳秋雲譯，e世代液晶顯示器，全華科技股份有限公司，第五章，民國90年。
36. 張瑞勳，國立台灣工業技術學院，碩士論文，民國83年。
37. G. W. Gray and ‎Hans W. Spiess, Physical Properties of Liquid Crystals (Wiley-VCH, 2009).
38. J. R. Hodkinson and I. Greenleaves, “Computations of Light-Scattering and Extinction by Spheres According to Diffraction and Geometrical Optics, and Some Comparisons with the Mie Theory,” J. Opt. Soc. Am. 53(5), 577–588 (1963).
39. R. Apetz and M. P. B. van Bruggen, “Transparent Alumina: A Light-Scattering Model,” J. Am. Ceram. Soc. 86(3), 480–486 (2003).
40. S. K. Wu, T. S. Mo, J. D. Lin, S. Y. Huang, C. Y. Huang, H. C. Yeh, and C. R. Lee, “Electrohydrodynamics-induced abnormal electro-optic characteristics in a polymer-dispersed liquid crystal film,” Crystals 7(7), 227–? (2017).
41. Q. Fu and W. Sun, “Mie theory for light scattering by a spherical particle in an absorbing medium,” Appl. Opt. 40(9), 1354–1361 (2001).
42. C. H. Chan, T. Y. Wu, M. H. Yen, C. E. Lin, K. T. Cheng, and C. C. Chen, “Low power consumption and high-contrast light scattering based on polymer-dispersed liquid crystals doped with silver-coated polystyrene microspheres,” Opt. Express 24(26), 29963–29971 (2016)
43. R. R. Deshmukh and A. K. Jain “The complete morphological, electro-optical and dielectric study of dichroic dye-doped polymer-dispersed liquid crystal,” Liquid Crystals 41(7), 960–975 (2014).
44. R. J. Martin. “Scattering Matrices for Slightly Non-spherical Particles,” J. Mod. Optics 42(1), 157–169 (1995).
45. A. M. Lackner, J. D. Margerum, E. Ramos, and K.C. Lim “Droplet Size Control In Polymer Dispersed Liquid Crystal Films,” SPIE 1080-53–1080-61, (1989).
46. J. Li, Refractive Indices of Liquid Crstals and Their Applications in Display and Photonic Devices (University of Central Florida, Florida, 2005).
47. 吳冠瑋,“手性分子液晶反射色彩的電熱調控,”國立交通大學照明與能源光電研究所，碩士論文，民國107年。