| 摘要: | 本論文主要探討以二維材料MXene薄膜作為液晶配向層之可行性，並系統性比較其與傳統機械摩擦聚醯亞胺(polyimide, PI)配向層於液晶盒中之配向行為與光電特性之差異。由於傳統摩擦式配向製程所伴隨之粉塵污染、表面損傷與靜電累積等問題，可能成為液晶元件製程之缺點，因此發展無摩擦製程且具良好配向能力之新型配向材料具有重要研究價值。故本研究利用旋轉塗佈製程於ITO玻璃基板上製備MXene薄膜，並以兩片塗佈完成之基板組裝成液晶盒，而後注入向列型液晶E7，透過偏光顯微鏡觀察其液晶配向狀態，以驗證MXene配向層在無摩擦條件下誘導液晶形成穩定水平配向之能力。實驗結果顯示MXene配向層可提供均勻且穩定之液晶排列效果，配向方向平行液晶注入液晶空盒時的流動方向，其配向品質可與傳統摩擦PI配向層相互比擬。進一步針對MXene液晶盒之光電特性進行量測，包含電壓‒穿透率曲線、動態反應時間及低頻電壓操作穩定性，並與PI 液晶盒進行比較。結果顯示，MXene液晶盒於操作電壓與動態切換行為上皆展現良好表現，且在特定MXene濃度條件下，其下降時間明顯縮短，顯示MXene配向層有助於提升液晶元件之動態反應效率。此外，在低頻電壓驅動條件下，MXene液晶盒亦展現較佳之穿透率穩定性。在界面性質分析方面，錨定能計算結果顯示，MXene配向層可提供高於傳統摩擦PI配向層之表面錨定能，顯示其能夠提供更高的表面能(~10-3 J/cm2)使液晶分子分佈更穩定；同時，高溫熱處理實驗結果亦證實MXene液晶盒在特定條件下具有良好之配向穩定性。綜合上述結果，本研究證實MXene薄膜具備作為新型無摩擦液晶配向層之應用潛力，未來可望應用於先進液晶顯示與新型光電元件之製程整合。;This thesis investigates the feasibility of employing two-dimensional MXene thin films as liquid crystal (LC) alignment layers and systematically compares their alignment behavior and electro-optical properties with those of conventional mechanically rubbed polyimide (PI) alignment layers in LC cells. Since traditional rubbing-based alignment processes are accompanied by issues, such as particle contamination, surface damage, and electrostatic charge accumulation, which may limit the performance and reliability of LC devices, the development of a rubbing-free alignment technique with effective alignment capability is of significant research interest. In this study, MXene thin films were fabricated on indium-tin-oxide (ITO)-coated glass substrates using a spin-coating process, and nematic LC E7 was filled into the LC cells. The LC alignment characteristics were examined using polarized optical microscopy to verify the ability of the MXene alignment layer to induce stable planar alignment under rubbing-free conditions. The experimental results demonstrate that the MXene alignment layer enables uniform and stable LC alignment, where the alignment direction is parallel to the LC flow direction during LC filling, and the resulting alignment quality is comparable to that of conventional rubbed PI alignment layers. Furthermore, the electro-optical properties of MXene LC cells were systematically characterized, including voltage–transmittance relationships, dynamic response times, and stability under low-frequency voltage driving, and were compared with those of PI LC cells. The results indicate that MXene LC cells exhibit favorable operating voltages and dynamic switching behaviors. Under specific MXene concentration conditions, a noticeably shortened fall time was observed, suggesting that the MXene alignment layer effectively enhances the dynamic response performance of LC devices. In addition, MXene LC cells show improved transmittance stability under low-frequency voltage operation. From the perspective of interfacial properties, anchoring energy analysis reveals that the MXene alignment layer provides a higher surface anchoring energy than the conventional PI alignment layer, indicating stronger interfacial constraints and more stable LC molecular alignment. Moreover, thermal treatment experiments confirm that MXene LC cells maintain good alignment stability under elevated temperature conditions. Overall, the results of this study demonstrate that MXene thin films possess strong potential as a novel rubbing-free LC alignment layer, offering promising prospects for integration into advanced LC displays and emerging optoelectronic devices. |
