本研究探討製程上蒸鍍源的顆粒大小與OLED光電的特性。超音波震盪過後的Alq3粉末粒徑小於市售的Alq3粉末，超音波震盪後的Alq3粉末堆疊緻密，熱傳導效果比較好，由超音波震盪後Alq3所構成的蒸鍍源其溫度相對於市售的Alq3所構成的蒸鍍源較高以及較恆溫。促進較高溫度梯度的蒸鍍製程，提升擴散通量，使氣體Alq3在基板上形成動力驅動的沉積模式，沉積出較小的微晶薄膜，提升元件的電子傳輸性。因為在此系統的固定膜厚下，較小的微晶薄膜阻擋電子能力下降，降低載子的結合率，其元件的電流效率較低。在10000 cd/m2亮度下為例，以超音波震盪後Alq3所構成的蒸鍍源製備出的單元件，其電流密度為0.23 A/cm2，而電流效率為4.55 cd/A，而以市售的Alq3蒸鍍源製備出的單元件，其電流密度為0.09 A/cm2，而電流效率為5.57 cd/A。掌握蒸鍍源粉末的大小分布與粉末間隙，即控制蒸鍍源粉末的熱傳導性，將更準確地控制在薄膜上元件的再現性，以及提升元件電子傳輸性。 The relationship between the particle size of the target source and the photoelectric characteristic of organic light-emitting diode (OLED) was investigated in this thesis. The insonated Alq3 particulates were smaller than the as-received Alq3 particulates. The insonated Alq3 particulates were compacted with a better connectivity which related to heat conduction. With better heat conduction, the Alq3 vapor was deposited on a substrate with a kinetically driven growth mechanism. Smaller crystallites were resulted in the thin film which gave a highly electronic transportation, leading to an increased current density. Because of the given thickness and the drop of the electronic blocking ability, the recombination probability of carriers by the smaller crystallite size in the thin film could not be enhanced. The insonated Alq3 produced device exhibited, at 10000 cd/m2, for example, the current density of 0.23 A/cm2 and the current efficiency of 4.55 cd/A, whereas the as-received Alq3 produced device displayed 0.09 A/cm2 and 5.57 cd/A, respectively. This suggested that the target source with compacted connection accompanied the improvement of the electronic transmission and the reproducibility of OLEDs for thermal evaporation process.
