本研究藉由製備ITO/poly(2-methoxy,5-(2´-ethyl-hexoxy)-1,4-phenylenevinylene)(MEH-PPV)(120 nm)/dielectric layer/Al (250 nm)元件，探討在MEH-PPV及Al界面間介電層結構對元件性能的影響。我們從元件電壓-電流-亮度特性曲線計算元件外部量子效率效率，再藉由量測UV-Vis吸收光譜、光激發光光譜及時間解析光激發光光譜計算MEH-PPV光激發光量子效率後，利用元件外部量子效率及MEH-PPV光激發光量子效率進一步計算得到載子再結合效率。
MEH-PPV及Al界面間含18~22 nm PMMA介電層元件或含0.8~1.2 nm含氧化鋁混合物介電層元件，其元件電壓-電流特性曲線顯示元件的起始電壓隨著介電層厚度增加而增加。經170℃熱處理ITO/MEH-PPV/Al元件之電壓-電流特性曲線顯示元件的起始電壓比未經過熱處理的元件低。藉由元件載子再結合效率計算結果發現，含氧化鋁混合物介電層元件載子再結合效率隨著加入介電層厚度增加而降低、經170℃熱處理的元件載子再結合效率比未經過熱處理的元件高，這是因為介電層厚度增加使得電子注入變困難，而170℃熱處理元件因為MEH-PPV高分子與Al金屬界面產生化學反應，電子注入能障相對於未經過熱處理元件低使電子注入較容易所造成。此外，我們發現元件最大亮度時，元件發光功率效率未達到最大。

This work is to prepare diodes consisting of ITO/poly(2- methoxy,5-(2′- ethyl-hexoxy)-1,4-phenylenevinylene)(MEH- PPV)(120 nm)/dielectric layer/Al(250 nm), and investigate the influence of the structure of dielectric layers between MEH-PPV and Al on device efficiencies. The measured voltage- current-brightness characteristics of devices were used to yield external quantum efficiency of devices. The UV-Vis spectra, steady and time-resolved photoluminescence of MEP-PPV in solution and bulk were combined to compute the photoluminescence efficiency of bulk polymer, leading finally to the carrier recombination efficiency in devices.
For PMMA dielectric (thickness= 18 to 22 nm) or mixtures containing aluminum oxide (thickness= 0.8 to 1.2 nm), the voltage-current curves of devices indicate an increase of turn-on voltage with the thickness of dielectric layer. ITO/MEH-PPV/Al device thermally treated at 170℃ is possessed with a lower turn-on voltage than the untreated one. The carrier recombination efficiency for devices with aluminum oxide dielectric decreases with layer thickness, whereas the recombination efficiency for thermally treated ITO/MEH-PPV/Al is higher than the untreated one. This is explained by the increasing barrier height for electron injection caused by the thicker dielectric layer, and the lowering of barrier height due to the formation of interfacial composition resulting from the interfacial reaction between MEH-PPV and Al cathode. Moreover, it is found that, while the device reaches the maximum brightness at a certain voltage, they do not offer the maximum luminous efficiency.

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