本文選題：有機(jī)發(fā)光器件 + 電子注入層��； 參考：《西南大學(xué)》2015年碩士論文

【摘要】：有機(jī)發(fā)光二極管(OLED)具有自主發(fā)光、廣視角、高效率、低功耗、可用于柔性顯示等特性,被認(rèn)為是下一代顯示技術(shù)最重要的技術(shù)之一,在OLED器件中,通常采用低功函數(shù)金屬如Ca和Ba來(lái)提高電子的注入效率,然而這些低功函數(shù)金屬對(duì)空氣中的水分和氧氣十分敏感,陰極金屬的失效將嚴(yán)重地影響器件的正常工作和驅(qū)動(dòng)穩(wěn)定性。研究引入了金屬氧化物如ZnO和TiO2作為電子注入層或通過(guò)對(duì)ITO進(jìn)行修飾來(lái)制備倒置結(jié)構(gòu)以解決這個(gè)問(wèn)題。然而,金屬氧化物到有機(jī)發(fā)光材料之間存在著很大的電子注入勢(shì)壘。本論文通過(guò)加入聚乙烯亞胺(PEIE)修飾層來(lái)提高電子的注入效率。論文主要的研究工作包括以下幾個(gè)方面：(1)在ITO或ITO/ZnO和發(fā)光層MEH-PPV層之間加入PEIE層有效地提高了器件發(fā)光效率。此外,在發(fā)光層與金屬Al之間加入PEIE層使器件的發(fā)光效率增加了50倍。加有PEIE層的單電子器件的電流密度比未加PEIE層的高出5-10倍,由此表明PEIE層能夠有效地改善了器件的電子注入能力,提高器件的發(fā)光效率。為了探究電子注入效率改善的機(jī)制,我們通過(guò)紫外線(xiàn)光電子能譜和X-射線(xiàn)光電子能譜法測(cè)量了PEIE/Al和ZnO/PEIE樣品的功函數(shù),發(fā)現(xiàn)在PEIE的修飾下ZnO和Al的功函數(shù)分別被降低了1.2 eV和1.0 eV,功函數(shù)的降低主要來(lái)源于界面偶極子層的形成。X射線(xiàn)光電子能譜的測(cè)量結(jié)果表明中性胺是降低功函數(shù)的主要原因。(2)為了探究從ZnO/PEIE到具有不同最低未占有軌道(LUMO)能級(jí)的發(fā)光材料的電子注入效率,我們研究了使用PF-TBT、SY和PFA分別作為發(fā)光層的有機(jī)-無(wú)機(jī)復(fù)合發(fā)光器件,其LUMO能級(jí)分別為-3.6、-2.7、-2.1 eV。這些有機(jī)-無(wú)機(jī)復(fù)合器件的發(fā)光效率與使用PEDOT:PSS和CsF作為空穴和電子注入層的傳統(tǒng)結(jié)構(gòu)器件的發(fā)光效率相似,由此表明從ZnO/PEIE到發(fā)光聚合物層的電子注入勢(shì)壘非常小。所以,對(duì)于LUMO能級(jí)差別較大的發(fā)光聚合物而言,PEIE都可以作為有效的電子注入層。(3)相比于普遍采用的Cs2CO3電子注入層,PEIE具有與有機(jī)材料接近的表面能并可形成均勻的薄膜,對(duì)有機(jī)發(fā)光層特別是包含磷光材料的發(fā)光層的形貌影響較小。因此,我們探究了基于溶液加工小分子材料發(fā)光層和PEIE電子注入層的有機(jī)-無(wú)機(jī)復(fù)合發(fā)光器件的發(fā)光特性。發(fā)光器件的最高發(fā)光效率是87.6 cd A-1,在亮度為1000 cd m-2時(shí),器件的外量子效率為20.9%。該器件的發(fā)光效率為以往報(bào)道的基于ZnO:Cs2CO3電子注入層的發(fā)光器件的4倍,這歸因于PEIE具有優(yōu)良的電子注入能力和空穴/激子阻擋能力,特別是PEIE與發(fā)光層之間可形成良好界面。
[Abstract]:Organic light emitting diodes (OLEDs) are considered as one of the most important technologies in the next generation of display technology, because they have the characteristics of independent luminescence, wide viewing angle, high efficiency, low power consumption, and can be used for flexible display. Low power function metals such as Ca and Ba are usually used to improve the efficiency of electron injection. However, these low power function metals are very sensitive to air moisture and oxygen, and the failure of cathode metals will seriously affect the normal operation and driving stability of the devices. Metal oxides such as ZnO and TiO2 were introduced as the electron implantation layer or modified by ITO to prepare the inverted structure to solve this problem. However, there are large electron injection barriers between metal oxides and organic luminescent materials. In this paper, the electron injection efficiency is improved by adding polyethylene imine (PEIE) modified layer. The main research work includes the following aspects: (1) adding PEIE layer between ITO / ITO / ZnO and MEH-PPV layer can effectively improve the luminescence efficiency of the device. In addition, the addition of PEIE layer between the luminescent layer and Al increases the luminescence efficiency by 50 times. The current density of single electron device with PEIE layer is 5-10 times higher than that without PEIE layer, which shows that PEIE layer can effectively improve the electron injection ability of the device and improve the luminescence efficiency of the device. In order to explore the mechanism of improving electron injection efficiency, we measured the work functions of PEIE-Al and ZnO / PEIE samples by ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy. It was found that the work functions of ZnO and Al were decreased by 1.2 EV and 1.0 EV respectively under the modification of PEIE. The decrease of work function was mainly due to the formation of interfacial dipole layer. The results of X-ray photoelectron spectroscopy showed that neutral amine was the reducing work function. (2) in order to explore the electron injection efficiency from ZnO / PEIE to luminescent materials with different lowest non-occupied orbital (LUMO) energy levels, Using PF-TBTSY and PFA as luminescent layers, the LUMO levels of organic-inorganic composite luminescent devices are studied. The LUMO levels are -3.6 ~ 2.7U ~ (-2.1) EV, respectively. The luminescence efficiency of these organic-inorganic composite devices is similar to that of conventional devices using PEDOT: PSS and CSF as hole and electron injection layers, which indicates that the electron injection barrier from ZnO / PEIE to luminescent polymer layer is very small. Therefore, PEIE can be used as an effective electron injection layer for luminescent polymers with different LUMO energy levels. (3) compared with the widely used Cs2CO3 electron implantation layer, PEIE has surface energy close to that of organic materials and can form a uniform film. It has little effect on the morphology of the organic luminescent layer, especially the luminescent layer containing phosphorescent material. Therefore, we investigated the luminescence characteristics of organic-inorganic composite luminescent devices based on solution fabrication of small molecular materials and PEIE electron implantation layers. The maximum luminescence efficiency of the device is 87.6 CD A-1. When the luminance is 1000 CD m-2, the external quantum efficiency of the device is 20.9. The luminescence efficiency of the device is 4 times higher than that of the previously reported device based on ZnO: Cs2CO3, which is attributed to PEIE's excellent electron injection ability and hole / exciton blocking ability, especially the good interface between PEIE and the luminescent layer.
【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TN383.1

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本文編號(hào)：2076159