石墨烯量子點是由數層石墨烯組成，直徑為數十奈米，表面和側面有數種化
學官能基修飾的準零維球狀奈米粒子，其內部電子在各方向上的運動都受到侷限
而表現出顯著的量子侷限效應和邊緣效應，導致能階不連續，當侷域狀態的電子
電洞對產生輻射復合時，即放出螢光。能階間隙與粒子大小有關，根據不同的合
成方法，石墨烯量子點的螢光可從深紫外到綠色甚至黃色。石墨烯量子點具有良
好的化學穩定性和生物相容性、低毒性、低成本、無光致漂白等優越的特性，在
生醫感測、細胞成像、光電元件等領域有無限的應用潛力。
本研究使用石墨烯量子點做為膽固醇液晶雷射的工作物質，取代傳統的雷射
染料。石墨烯量子點以二片膽固醇液晶夾成三明治結構，調整螺距使二片膽固醇
液晶的反射波段只有一邊重疊。為降低石墨烯量子點膽固醇液晶雷射的輸出能量
閾值，將膽固醇液晶樣品經過熱退火的機制使內部缺陷移除，以減少共振腔的損
耗，並配合石墨烯量子點的最佳濃度，經激發後可產生雷射輸出。

Graphene quantum dots (GQDs) are zero dimensional quasi-spherical nanoparticles with diameter from several nanometers to tens of nanometers, consisting of one or a few graphite layers. GQDs generally possess functional groups decorated at basal plane and lateral edge. Besides the factor of size, these characteristic functional groups provide quantum confinement, and lead to discrete quantum states. The electron-hole pairs within localized states can recombine radiatively and emit luminescence. The energy gap generally depends on the size of the GQDs. The luminescence can be varied from deep ultraviolet to green even yellow by different method for the synthesis of GQDs. Due to their superiority in chemical inertness,excellent biocompatibility, low toxicity, low cost, and resistance to photobleaching,GQDs have wide potential applications in biosensor, bioimaging, and photovoltaic.
In this study, GQDs were used to serve as the active material for cholesteric liquid crystal laser, replacing the conventional laser dyes. GQDs were sandwiched between two cholesteric liquid crystal cells. The pitch of one cholesteric liquid crystal layer was shifted with respect to the other so that only the edges of reflective bands overlapped. To lower the lasing threshold of the sandwich cell, the defects in the cholesteric liquid crystal layers were removed by an annealing process. In addition to reducing the cavity loss, the concentration of GQDs was chosen to get maximum fluorescence. Coherent lasing with narrow spectral width was observed after optical excitation.

目錄
摘要……………………………………………………………………………………...I
Abstract…………………………………………………………………………………II
誌謝…………………………………………………………………………………...III
目錄………………………………………………………………………….…………IV
圖目錄………………………………………………………………….........................VI
表目錄…………………………………………………………………………………IX
第一章、簡介……………………………………………………………………………1
1-1、前言………………………………………………………………………………1
1-2、何謂液晶………………………………………………………………………3
1-3、液晶的分類………………………………………………………………………3
1-4、液晶物理特性……………………………………………………………………12
1-4-1、液晶雙折射性……………………………………………………………12
1-4-2、液晶連續彈性體理論……………………………………………………15
1-4-3、溫度對向列型液晶的影響………………………………………………16
1-4-4、電場對向列型液晶的影響………………………………………………17
第二章、理論介紹……………………………………………………………………19
2-1、膽固醇液晶……………………………………………………………………19
2-1-1、熱退火對於膽固醇液晶的影響…………………………………………19
2-1-2、膽固醇液晶光學特性與雷射機制………………………………………19
2-1-3、膽固醇液晶雷射的缺陷模式…………………………………………….23
2-2、石墨烯量子點…………………………………………………...……….………24
2-2-1、石墨烯簡介…………………………………..............................24
2-2-2、石墨烯量子點簡介……………………………………………………….25
2-2-3、石墨烯量子點的合成…………………………………………………….26
2-3、量子點的特性………………………………..........................26
第三章、實驗方法與過程………………….............................31
3-1、材料介紹…………………………………………………………………………31
3-2、樣品空盒的製作…………………………………………………………………33
3-3、樣品製作…………………………………………………………………………34
3-4、實驗架設………………………………………………………………………...38
第四章、實驗結果與討論…………………………………………………………….40
4-1、石墨烯量子點的吸收與穿透量測………………………………………………40
4-2、石墨烯量子點的螢光量測………………………………………………………41
4-3、三明治夾層樣品的特性量測……………………………………………………44
4-3-1、完美平面螺旋結構的膽固醇液晶樣品………………………………….44
4-3-2、膽固醇液晶樣品的穿透量測…………………………………………….46
4-3-3、灌入石墨烯量子點的三明治夾層樣品穿透頻譜量測………………….47
4-3-4、灌入石墨烯量子點的三明治夾層樣品螢光量測………………………48
4-4、三明治夾層樣品雷射輸出量測…………………………………………………50
第五章、結論與未來展望........................................54
參考文獻...................................................56

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