共軛高分子水平元件中電荷傳輸特性

Abstract

為了解決傳統共軛聚合物元件中載子低遷移率的問題，在本文中，我們利用電子束微影技術製作水平結構，使電極平行於電流方向。其結構為Au/MEH-PPV/Au，使電洞在intrachain上傳輸，我們預期其有較小的電阻和較大的載子遷移率。並改變金屬電極間的距離，從0.9 micron到14.7 micron，量測電流電壓的曲線，得到水平結構中電洞的遷移率，發現其遠大於傳統三明治結構的遷移率，大約102到103倍。且發現電洞遷移率和傳輸間的距離無明顯的關係。在改變間距的同時，同時改變量測時的溫度，瞭解電洞遷移率和溫度的相關性。隨著溫度的降低，電洞遷移率亦隨著指數性的降低。而實驗所得的熱活化能障約為三明治結構的1/2。

In order to solve the problem of the low carrier mobility in conjugated polymer, we use EBL(electron beam lithography) to fabricate the horizontal device with the electrodes parallel to electric current direction. The horizontal device is made up of Au/MEH-PPV/Au, and the hole carriers transport along the intra-chain instead of inter-chain hopping. Therefore, it is expected that there will be less resistivity and higher carrier mobility. We change the distance between the Au electrodes, ranging from 0.9 micron to14.7 micron, and measure the current-voltage curve to get the hole mobility in the horizontal device. It is found that the carrier mobility is about 102 to 103 much larger than the traditional sandwich structure. Besides, there is little dependence between the hole mobility and carrier transport distance. As the electrode distance is changed, we also change the measurement temperature to understand the temperature dependence of hole mobility. With the decrease of the temperature, the hole mobility decreases exponentially. In addition, the thermal activation energy gap is approximately half of that of the sandwich device.