基于p-型掺杂空穴传输层的高效绿色磷光有机电致发光器件

发布时间：2018-01-15 18:36

本文关键词：基于p-型掺杂空穴传输层的高效绿色磷光有机电致发光器件　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：近几十年来,有机电致发光器件(Organic Light-emitting Devices,OLEDs)以其轻薄、柔性、低功耗和面光源等诸多优越性能已经成为下一代全彩显示、固态照明的佼佼者。而OLEDs是由阴、阳电极中间夹着空穴传输层、发光层、电子传输层等有机功能层的“三明治”式结构构成。其中的空穴传输层(Hole Transporting Layer,HTL)是有机功能层的重要组成部分,其空穴传输性能直接决定了空穴向发光层的传输和注入过程,进而影响到载流子的平衡复合,并最终影响器件的性能。然而有机空穴传输材料本身具有空穴迁移率偏低、导电性偏差以及与金属电极接触不良导致的注入势垒偏高等诸多短板限制了器件性能的提高。而通过p-型掺杂技术将p-型掺杂剂掺杂到HTL中构成的p-型掺杂空穴传输层,由于显著地改善了HTL的空穴传输性能,得到广泛应用。为了提高基于Ir(ppy)3的绿色磷光OLEDs器件性能,本文设计了不同的p型掺杂结构HTL,以改善器件性能。主要工作如下:1.利用p-型共掺杂结构(CBP:Mo O_3/CBP)的HTL制备了共掺结构(Co-evaporating Structure,CS)以及混合共掺结构(Mixed Structure,MS)绿色磷光OLEDs。首先优化了CS器件,基于20nm掺杂层厚度和50%掺杂浓度共掺杂HTL的器件性能最优,最大亮度(97880 cd/m2)和最大功率效率(22 lm/W)分是参比器件的52倍和1.3倍。然后优化了MS器件,p-型共掺杂HTL最优的掺杂浓度为50%,厚度为30 nm,故其最大亮度(152600cd/m2)与参比器件相比提高51%,最大功率效率(49 lm/W)提高26%。最后通过对相应的单空穴器件的表征,得出了器件性能的提高归因于p-型共掺杂HTL可提高HTL传输性能及其导电性,提高空穴浓度,降低驱动电压,从而具有更高的亮度和效率的结论。2.采用周期性结构[Mo O_3(3 nm)/CBP]n构成周期性p-型层掺杂HTL,降低了OLEDs启亮电压,提高器件亮度与功率效率。首先进行了周期性p-型层掺杂HTL的优化。其次通过单空穴器件的表征,阐明周期性p-型层掺杂HTL由于改善了HTL的空穴传输性能进而提高了器件的亮度和效率。而三周期器件D-3由于具有最优的掺杂浓度和最适宜的层状Mo O_3空间分布,因而具有最高的最大电流效率(56 cd/A),最大EQE(15.6%)和最大功率效率(45 lm/W)的同时具有最低的效率滚降与启亮电压(3.2 V)。然后通过对比,器件D-3的最大功率效率也要比基于共掺杂结构HTL的参比器件提高18%,这表明了周期性p-型层掺杂结构HTL的优越性。最后对周期性p-型层掺杂HTL的掺杂机理进行了阐述。3.利用C_(60)和Cu Pc形成有机半导体异质结作为基于CBP:Mo O_3的p-型共掺杂结构HTL/ITO阳极的界面修饰层,制备了高效绿色磷光OLEDs。与常规Mo O_3阳极修饰层相比,C_(60)(5 nm)/Cu Pc(25nm)为面异质结最优修饰结构,器件的最大电流效率和EQE提高了12%和11%,分别为60 cd/A和16.8%;而Cu Pc:C_(60)(30 nm,50%)体异质最优修饰结构器件则提高了26%和27%,分别为67cd/A和19.3%。高的器件效率一方面归因于C_(60)与Cu Pc异质结界面处积累的电荷会在电压的作用下形成高效的电荷分离和空穴注入;另一方面归因于C_(60)与Cu Pc异质结具有吸收器件内部绿光光子形成光生载流子的光伏效应。利用Cu Pc:C_(60)体异质结作界面修饰层的器件由于具有更高效的电荷积累、更合适的空穴传输性从而达到更平衡的载流子复合以及更好的光伏特性,因而器件效率要比C_(60)/Cu Pc更优。
[Abstract]:In recent decades, organic electroluminescent devices (Organic, Light-emitting Devices, OLEDs) with its thin, flexible, low power consumption and light and other excellent properties has become the next generation of full-color display, all solid-state lighting. While the OLEDs is from the Yin and Yang electrode sandwiched between the hole transport layer, a light-emitting layer, electronic the transport layer of organic functional layer "sandwich" structure. The hole transport layer (Hole Transporting Layer, HTL) is an important part of the organic functional layer, the hole transport performance directly determines the transmission to the light emitting layer and a hole injection process, and affect the balance of carrier compound, and ultimately affect the device the performance. However the OHTMs itself has low hole mobility, electrical conductivity and metal electrode bias and poor contact caused high barrier into many short board limits the performance of the device Improved. And the p- type dopant doped p- type doped hole transport layer HTL formed by p- type doping technology, due to significantly improve the transmission performance of HTL hole, has been widely used. In order to improve based on Ir (PPy) 3 green phosphorescent OLEDs device performance, this paper introduces the design of P type doping structure different HTL, in order to improve the performance of the device. The main work is as follows: 1. using p- Co doped structure (CBP:Mo O_3/CBP) Co doped structure by HTL (Co-evaporating Structure CS) and mixed Co doped structure (Mixed Structure, MS) OLEDs. green phosphor was optimized firstly CS device, 20nm device performance optimal doping layer the thickness and doping concentration of Co doped HTL 50% based on the maximum brightness (97880 cd/m2) and the maximum power efficiency (22 lm/W) is 52 times the reference device and 1.3 times. Then optimize the MS device, the doping concentration p- Co doped HTL optimal is 50%, the thickness of 3 0 nm, the maximum brightness (152600cd/m2) and the reference device is 51% higher than that of maximum power efficiency (49 lm/W) to improve the 26%. finally through the characterization of single hole corresponding device, the device performance is attributed to the increase of type p- Co doped HTL can improve the transmission performance of HTL and conductivity, increase the hole concentration to reduce the driving voltage, which has higher brightness and efficiency of the conclusion.2. using periodic structure of [Mo O_3 (3 nm) /CBP]n periodic p- type layer doped HTL, reduces the OLEDs turn-on voltage, improve the brightness and power efficiency. The first optimization layer of HTL doped p- type second periodic. Through the characterization of single hole devices, clarify the periodic p- type doped HTL layer due to the improvement of the transmission performance of HTL hole and improves the brightness and efficiency of device. And the three cycle D-3 device because the doping concentration has the best and the most suitable layered Mo O_3 The spatial distribution, thus has the maximum current efficiency is the highest (56 cd/A), EQE (15.6%) and the maximum power efficiency (45 lm/W) and has the lowest efficiency roll and the turn-on voltage (3.2 V). Then by comparing the maximum power efficiency of D-3 devices than Co doped HTL structure. Based on the 18% higher than the device, it shows the superiority of the periodic p- type doping layer structure of HTL. Finally the mechanism of doping periodic p- type doped HTL layer are described by.3. C_ (60) and Cu Pc to form an organic semiconductor heterojunction as p- CBP:Mo based on O_3 Co doped HTL/ITO anode interface structure the modified layer was prepared by high efficient green phosphorescent OLEDs. and conventional Mo O_3 anode modification layer compared to C_ (60) (5 nm) /Cu Pc (25nm) optimal structure for surface modification of heterogeneous devices, the maximum current efficiency and EQE increased by 12% and 11%, respectively, 60 cd/A and 16.8% Cu (Pc:C_; 60 (30) Nm, 50%) the heterogenous optimal modified structure devices increased by 26% and 27%, respectively 67cd/A and 19.3%. high device efficiency on the one hand due to the C_ Cu Pc (60) and the charge accumulation at the interface of the heterojunction will charge separation and hole injection in the formation of efficient voltage effect; on the other hand, due to the C_ (60) and Cu Pc heterojunction with absorption device internal green photons to form the photovoltaic effect of photogenerated carrier. Using Cu Pc:C_ (60) bulk heterojunction devices interface modification layer with more efficient charge accumulation, hole transport is more appropriate to achieve a more balanced and better photovoltaic properties of composite carrier therefore, the efficiency of the device than the C_ (60) /Cu Pc better.

【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN383.1

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