以有機磷酸修飾電極表面功函數及對有機發光元件效率影響研究; Modulation of electrode surface work function with phosphonic acid derivatives for application in Organic Light-emitting devices

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6544

Title:	以有機磷酸修飾電極表面功函數及對有機發光元件效率影響研究;Modulation of electrode surface work function with phosphonic acid derivatives for application in Organic Light-emitting devices
Authors:	陳宜伶;Yi-ling Chen
Contributors:	化學研究所
Keywords:	有機發光元件;Organic Light-emitting devices
Date:	2009-07-08
Issue Date:	2009-09-22 10:21:33 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本研究主要分為三個部分，第一部份是合成不同碳數末端是三氟甲基的長碳鏈磷酸，另外還用不同碳鏈長度的飽和磷酸吸附在鋁上形成自組裝薄膜，藉由橢圓儀、紅外光譜儀、接觸角和光電子光譜儀進行表面性質分析。第二部分是用這些磷酸分子吸附在ITO上，並利用兩個極性相反的分子製備混和自組裝薄膜，利用接觸角、光電子光譜儀和X光電子能譜儀進行表面分析。第三部分則是以這些磷酸分子修飾過的ITO為陽極，製成底部發光元件，研究這些修飾對於元件電流密度和發光效率的影響。第一部份研究結果顯示，磷酸在鋁上的排列會隨著碳數增加而有較好的排列，且依照不同比例混合製備混合自組裝薄膜時，分子吸附在鋁上的比例和在溶液中的比例很接近。第二部分的結果顯示，經過混合比例磷酸修飾的ITO表面功函數的數值會隨著三氟甲基比例的增加而變大，而且是呈線性增加。第三部分的結果顯示，結構為ITO-SAM/ HTL/ Alq3/ LiF/ Al的元件，不論是以NPB或BPAPF為電洞傳輸層，電流密度皆隨著碳鏈長度的增加而變小，發光效率則是隨著碳鏈長度增加而上升。在此主要是碳鏈長度不同造成的穿隧障礙為影響發光效率的主因。若以混合比例的磷酸修飾ITO，且元件結構改為ITO-SAM/ BPAPF/ Alq3/ LiF/ Al ，則其電流密度隨著功函數數值的增加而上升，並以混合比例為1:1的元件有最好的發光效率。 The thesis is divided into three parts. The first part deals with the synthesis of CF3-terminated alkanephosphonic acid molecules with different chain lengths and the self-assembled monolayers(SAMs) formed by these molecules on Al substrate. SAMs of CH3-terminated alkanephosphonic acids with different chain lengths were also formed for comparison. Mixed monolayers formed from these two components were prepared. The surface structures and properties were characterized by using ellipsometry, reflection absorption IR (RAIR), contact angle and photoelectron spectrometer (AC-2). In the second part, similar monolayers as well as mixed monolayers were formed on ITO substrate. The surface properties were investigated by contact angle, photoelectron spectrometer, and X-ray photoelectron spectroscopy. A linear correlation between the ITO work function and the composition of the adsorbing solutions was observed. In the third part, organic light-emitting devices were fabricated with SAM-modified ITO as the anode substrate. The I-V curves, current density, and the luminous efficiency were analyzed to elucidate the charge balance situation in the devices. The performance of the devices with a configuration of ITO-SAM/HTL/Alq3/LiF/Al showed that, with molecules of same terminal functional group as modifier, the current density decreased with increasing chain length, whereas the luminous efficiency increased with increasing chain length. On the other hand, with mixed monolayer as modifier, the current density depends on the work function and thus the injection barriers. The luminous efficiency exhibits a maximum with ITO modified with 1:1 ratio of fluorinated and protiated hexanephosphonic acid as anode, suggesting a more balanced hole/electron carriers under the specific condition.
Appears in Collections:	[Graduate Institute of Chemistry] Electronic Thesis & Dissertation

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