多層結構有機電晶體之研究;Research on Multilayer Organic Field Effect Transistors

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/65120

Title:	多層結構有機電晶體之研究;Research on Multilayer Organic Field Effect Transistors
Authors:	陳威任;Chen,Wei-Ren
Contributors:	光電科學與工程學系
Keywords:	電晶體;有機;多層式;發光;transistor;organic;multilayer;light-emitting
Date:	2014-07-21
Issue Date:	2014-10-15 14:41:17 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文為實作並探討以具高載子遷移率的P型小分子材料(DNTT)與N型小分子材料(DFH-4T)製作之多層結構有機電晶體之特性，包括雙層結構的雙極性有機電晶體，以及三層結構的有機發光電晶體，並藉由有機層的薄膜形貌與微結構，以及材料能階等資訊，分析元件的光電特性及影響機制。在雙極性有機電晶體中，我們進行DNTT及DFH-4T不同的堆疊順序與一系列不同上接觸電極的研究，以優化載子遷移率與注入效率。實驗中發現N型材料(DFH-4T)在介電材料(PMMA)上成膜時會形成特殊的晶體堆疊形貌。此特殊薄膜形貌對於隨後沉積的DNTT與上金屬接觸具有雙重效果：(1)P型材料(DNTT)沉積於其上仍具備良好的成膜品質和電洞遷移率；(2)金屬沉積於其上可滲透進入有機層，使金屬與有機層之間接觸面積增加，因此利用高功函數金屬作為電極也能有效注入電子。隨後，在使用DFH-4T /DNTT之先後堆疊順序與使用高功函數金屬(Ag)的情況下，我們成功證實電子及電洞載子遷移率皆達到1 cm2/Vs數量級的雙極性有機電晶體。本研究接著在DFH-4T及DNTT有機材料之間插入一層發光層，提供電洞及電子複合的空間，使有機電晶體具備發光的特性。考量DFH-4T與DNTT的能階，我們選用能隙較小的紅光磷光材料(Ir(piq)3)作為客體發光材料，掺雜於主體螢光材料(Bebq2)中，形成發光層。我們進行一系列實驗，探討在發光層中磷光材料的掺雜比例，以及有機材料沉積順序和最下層材料的厚度對有機發光電晶體外部量子效率的影響。在磷光材料掺雜比例為10 wt %、DNTT/Bebq2:Ir(piq)3/DFH-4T的先後沉積順序、以及下層DNTT為10 nm的條件下，得到最高的外部量子效率達0.2 %。此發光電晶體之重要特色為具備近百微米的寬發光帶，並可產生高發光強度，具有發展顯示器應用之潛力。 ;This thesis investigates the multilayer organic field effect transistors fabricated with high-mobility P-type (DNTT) and N-type (DFH-4T) small molecular semiconductors. We characterize the devices including ambipolar field effect transistors and trilayer light-emitting transistors, and correlate their optoelectronic performance with the morphology, microstructures, and the energy levels of organic films. For ambipolar field effect transistors, we perform a series of study on different deposition order of organic films and different top contact electrodes to optimize the mobilities and injection efficiencies of electrons and holes. We observe that N-type organic semiconductor material (DFH-4T) as deposited on dielectric material (PMMA) would form a unique morphology with randomly packed large-sized crystals. Such a unique morphology of DFH-4T has dual effects on the sequential deposition of DNTT and top contact metals: (1) The film quality of P-type materials (DNTT) remains good and hence a high mobility of holes; (2) Evaporated metals will easily penetrate into the bulk of organic films, resulting in an increased contact area between metals and organic films. Therefore, electron injection can be still efficient even using high work-function metals. With DFH-4T/ DNTT deposition order and high work function metal (Ag), we demonstrate the ambipolar organic field effect transistors with electron mobility and hole mobility exceeding 1 cm2/Vs. Next, we insert a light-emitting layer into the DNTT and DFH-4T, to provide a space for electrons and holes to recombine and emit light. In consideration of the energy level of DNTT and DFH-4T, we choose the red phosphorescent material (Ir(piq)3) with a narrow energy bandgap as the guest material, and dope it into the fluorescence material (Bebq2) as the host material to form the light-emitting layer. We perform a series of experiments to understand the effects of the doping concentration of phosphorescent materials in the emitting layer, deposition order of organic semiconductors, and the thickness of the bottom layer (DNTT) on the EQE of organic lighting-emitting transistor. With the doping concentration of 5-10 wt %, deposition order of DNTT/Bebq2:Ir(piq)3/DFH-4T , and 10 nm DNTT as bottom layer, we achieve the highest EQE up to 0.2 %. This light-emitting transistor has significant features of the broad recombination zone approaching to 100 mm and the high emissive intensity, which is promising for display applications in the future.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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