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研究生：	馮冠文 Feng, Guan-Weng
論文名稱：	高分子發光二極體元件於變溫量測下特性之研究 The characteristics of polymer light-emitting diodes with varied temperature
指導教授：	郭宗枋 Guo, Tzung-Fang
學位類別：	碩士 Master
系所名稱：	理學院 - 光電科學與工程研究所 Institute of Electro-Optical Science and Engineering
論文出版年：	2006
畢業學年度：	94
語文別：	中文
論文頁數：	77
中文關鍵詞：	空間電荷、低溫、變溫、有機電激發光元件、聚芴高分子
外文關鍵詞：	organic light-emitting diodes, space charge, ultra low temperature, varied temperature, SCLC, polyfluorene, PLED, OLED
相關次數：	點閱：122 下載：3
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本論文使用自製之低溫控制機具結合光電特性測量系統進行低溫恆溫以及低溫變溫下操作元件之實驗，目的在極低溫下能凍結有機膜的相貌，藉由低溫操作下維持元件之發光顏色，證明我們對於聚芴高分子藍光有機電激發光二極體於常溫操作下變色機制是屬於薄膜型貌變化的假設，而非先前文獻所言的屬於高分子劣化反應。找出聚芴高分子藍光元件在偏壓作用下變化原因，提供一合理正確的藍光材料必須改進的方向。
另外，使用對溫度變化修正過之SCLC(Space Charge Limited Current)公式來檢視低溫變溫下聚芴高分子及其他共軛高分子電洞(Hole-only)元件電特性，並依照擬合之相符程度提出電洞元件J-V曲線特性在低溫下之合理解釋。各種材料之電洞元件於低電場(< 3×105 V/cm)下(電荷注入點之前)之電特性符合移動率固定之SCLC，而高於此電場則必須考慮到Poole-Frenkel effect 對載子移動率帶來的影響。
最後在低溫變溫測量中發現PLEDs電激發光光譜的兩個現象，降溫下EL光譜紅位移現象及降溫下元件效率提升現象。在參考無機半導體或螢光體低溫下測量之文獻，對這兩項發現做出合理的解釋為低溫下分子熱擾動減少，電子在激發態的時間變長，有足夠的時間讓激發的電子緩解至最低激發態能階再行放光，所以平均發光能隙減少。此外，低溫下分子振動情況降低避免激子產生非輻射放射，所以低溫下EL增強。

In this thesis, we proposed that the mechanism of color shifting of polyfluorene(PFO) light emitting devices is polymer film morphology reformation during operating in room temperature. In low temperature environment, about 85K, the color shifting was not happened instead of red-shift in room temperature. This result indicated the color shift is not caused by material degradation which was reported in other groups’ study, and provided a value information for improvement of blue polymer LED (PLED) material.
Also, in low temperature environment, J-V characteristics of PFOs and many conjugated polymer devices were compared with the results of temperature-dependent Space Charge Limited Current(SCLC) simulation. It was found that J-V curves of these polymers were well matched with SCLC in low electric field(<3×105 V/cm) and with fixed carrier mobility. When electric field is stronger than 3×105 V/cm), Poole-Frenkel effect which influences carrier mobility must be taken into account.
Finally, two electroluminescence (EL) phenomenon were observed in different temperature measurements. When temperature decreased, one was that red-shifting of EL spectrum, and the other was the increasing of PLED efficiency. Based on inorganic semiconductor theories, these phenomenon were implied that molecular thermal vibration is lower, relaxation life time is longer, and non-radiative transition is reduced in low temperature.

中文摘要....................................................................................I
英文摘要................................................................................. III
誌謝......................................................................................... IV
目錄...........................................................................................V
表目錄...................................................................................VIII
圖目錄......................................................................................IX
符號及物理參數說明...........................................................XIII
第一章 緒論...............................................................................1
 1-1 前言.................................................................................... 1
   1-1-1 有機電激發光二極體的歷史簡介................................2
   1-1-2 有機電激發光二極體顯示器的最新發展及應用........3
 1-2 有機電激發光二極體外觀及結構簡介(共軛高分子系)...5
 1-3 研究動機與目的..................................................................6
 1-4 各章提要..............................................................................7
第二章 有機暨高分子發光二極體發光原理與文獻回顧......10
 2-1 有機電激發光二極體之發光原理....................................10
   2-1-1 有機及無機電激發光機制概略比較...........................10
   2-1-2 有機電激發及元件發光流程簡述...............................13
   2-1-3 有機電激發光二極體電荷注入理論...........................14
     2-1-3~1  Richardson-Schottky 熱激發載子注入理論..........14
     2-1-3~2  Fowler-Nordheim 穿隧理論...................................15
   2-1-4 有機電激發光二極體之電洞元件載子傳導理論.......16
     2-1-4~1 空間電荷侷限電流.................................................16
     2-1-4~2 無陷阱、低電場理論模型Child's law...................17
     2-1-4~3 高電場下考慮Poole-Frenkel theorem載子
                   hopping傳導的理論模型.......................................18
     2-1-4~4 變溫下考慮載子移動率隨溫度改變的理論模
                   型............................................................................18
 2-2 聚芴高分子藍光元件變色及改善之文獻回顧................20
   2-2-1 聚芴高分子之低分子量部分影響...............................20
   2-2-2 聚芴高分子鏈上氧化產生酮缺陷影響.......................21
   2-2-3 聚芴高分子間的聚集影響...........................................21
第三章 元件製作暨實驗裝置..................................................23
 3-1 元件製作流程....................................................................23
   3-1-1 ITO基板黃光製程........................................................23
　 3-1-2 ITO基板清洗與UV-ozone前處理..............................24
   3-1-3 塗布有機薄膜...............................................................25
   3-1-4 真空熱蒸鍍陰極金屬...................................................27
 3-2 聚芴高分子藍光變色機制研究實驗設置........................28
 3-3 PLEDs變溫光電特性測量系統實驗設置.........................31
第四章 低溫下Polyfluorene PLEDs變色機制研究..................33
 4-1 前言....................................................................................33
 4-2 實驗與結果討論................................................................34
   4-2-1 元件結構與材料...........................................................34
   4-2-2 流程設計與結果討論...................................................35
     4-2-2~1 實驗設計.................................................................35
     4-2-2~2 實驗流程結果討論.................................................36
 4-3 結論....................................................................................47
第五章 PLEDs在變溫操作下之特性研究...............................49
 5-1 前言....................................................................................49
 5-2 實驗與結果討論................................................................50
   5-2-1 元件結構與材料...........................................................50
   5-2-2 流程設計與結果討論...................................................52
     5-2-2~1 實驗設計.................................................................52
     5-2-2~2 實驗流程結果討論.................................................53
 5-3 結論....................................................................................68
第六章 未來研究建議..............................................................70
第七章 總結..............................................................................72
參考文獻...................................................................................73
自述...........................................................................................77
                                    

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校內：2007-06-28公開
校外：2007-06-28公開

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