基于TADF材料结构简单的高效蓝光及白光器件研究

发布时间：2018-03-31 21:12

本文选题：有机蓝光与白光器件　切入点：热激活延迟荧光材料　出处：《西南大学》2017年硕士论文

【摘要】：有机发光二极管(Organic light-emitting diode,OLED)因具有宽视角、反应快、可弯曲、低功耗、质量轻等优点被广泛应用于平板显示和固态照明设备中。在电激发下,有机发光二极管产生单线态激子和三线态激子,二者数目比例为1:3。传统荧光发光材料种类多,发光覆盖可见光,器件稳定性好,但传统荧光材料中只有单线态激子能被利用进行发光,75%的三线态激子以非辐射发光的方式退激活,极大地限制了器件效率。为了提高器件的发光效率,磷光材料被研发应用于有机发光二极管中。由于磷光材料能同时利用单线态激子和三线态激子发光,基于磷光材料的有机发光器件的内量子效率可达到100%。然而,蓝色磷光材料器件的驱动稳定性有待进一步提高,且磷光材料中含有铱、铂等贵金属导致了其价格昂贵,器件制备成本较高。TADF(thermally activated delayed fluorescence)材料在不含贵金属的情况下能同时利用单线态激子和三线态激子发光,被称为是继荧光材料和磷光材料之后的第三代有机光电材料,引起广泛关注。其中,蓝色TADF材料双[4-(9,9-二甲基-9,10-二氢吖啶)苯基]硫砜(DMAC-DPS)在掺杂与非掺杂型器件中均展示了良好的发光特性。本文主要研究了基于蓝色TADF材料DMAC-DPS的器件特性,主要包括以下几个方面:(1)研究了基于DMAC-DPS的非掺杂型器件,分别讨论了器件的空穴传输层、电子传输层以及发光层厚度对器件特性的影响。制备了结构为ITO/MoO3(5nm)/mCP(40 nm)/DMAC-DPS(30 nm)/SPPO13(50 nm)/CsF(1 nm)/Al(150 nm)的DMAC-DPS非掺杂型器件,器件的外量子效率和功率效率分别是14.3%和26.8 lm W-1。进一步通过比较单极性载流子器件的I-V特性,发现器件中空穴是多数载流子,载流子复合区域靠近发光层与电子传输层的界面。(2)在以上非掺杂型器件的基础上,在DMAC-DPS发光层中掺入不同比例的蓝色荧光材料TBPe,制备了结构为ITO/MoO3(5 nm)/mCP(40 nm)/DMAC-DPS:TBPe(30 nm)/SPPO13(50 nm)/CsF(1 nm)/Al(150 nm)的TADF敏化荧光器件。研究了TBPe掺杂浓度对器件的I-V-B特性、发光效率-电流密度特性及电致发光光谱特性的影响。DMAC-DPS:1.0%TBPe器件的外量子效率是12.7%,接近DMAC-DPS非掺杂型器件的外量子效率。器件色度为(0.15,0.25),较DMAC-DPS非掺杂型器件色度(0.16,0.27)有所改善。进一步讨论了DMAC-DPS:TBPe器件中激发态的产生与演变过程。(3)为了避免TADF敏化荧光器件中多种能量损耗机制对器件效率的影响,我们选择在DMAC-DPS中掺入绿色TADF材料2,4,5,6-四(9-咔唑基)-间苯二腈(4CzIPN)和黄色TADF材料2,3,5,6-四(3,6-二苯基-9-咔唑基)-对苯二腈(4CzTPN-Ph),制备了结构为ITO/MoO3(5 nm)/mCP(40 nm)/DMAC-DPS:G/YTADF(30 nm)/SPPO13(50 nm)/CsF(1 nm)/Al(150 nm)的全TADF发光器件。绿光器件最大外量子效率和最大功率效率分别为为10.9%和32.1 lm W-1,黄光器件的器件最大外量子效率和最大功率效率分别为11.0%和36.6 lm W-1。在该类器件中我们可以在保持较高外量子效率的前提下,较大范围地调节客体材料的掺杂浓度而得到同时具有较好发光效率和发光色纯度的器件。另外我们还发现,与在普遍采用的主体材料CBP中相比,在DMAC-DPS中,4CzTPN-Ph的发光发生了约30 nm的蓝移,这主要来源于不同的主体和客体材料的偶极相互作用。(4)在上述DMAC-DPS:4CzTPN-Ph器件研究的基础上,降低4CzTPN-Ph的掺杂浓度,制备了结构为ITO/MoO3(5 nm)/mCP(40 nm)/DMAC-DPS:4CzTPN-Ph(30 nm)/SPPO13(50 nm)/CsF(1 nm)/Al(150 nm)的白光器件。其中,0.4%4CzTPN-Ph的器件拥有最高14.7%外量子效率。0.8%4CzTPN-Ph的器件色度为(0.29,0.39),最接近白光且器件色度稳定较好。测量的DMAC-DPS:0.4%4CzTPN-Ph薄膜的光致发光光谱和瞬态光谱,光致发光光谱中同样发现550 nm处的发光且在对瞬态光谱中延迟发光部分用双指数衰减模型拟合得出其寿命为0.7μs和2.6μs,与文献报道相近,排除了DMAC-DPS与4CzTPN-Ph形成激基复合物的可能。探讨了DMAC-DPS:TADF器件中激发态的产生与演化原理并与同TADF敏化荧光器件进行了对比,DMAC-DPS:4CzTPN-Ph器件同DMAC-DPS器件几乎相同的外量子效率证明了全TADF器件能有效利用主客体材料产生的全部激子发光,减少了能量的损失。
[Abstract]:Organic light emitting diode (Organic light-emitting diode, OLED) with wide viewing angle, fast response, flexible, low power consumption, light weight and other advantages is widely used in flat-panel displays and solid-state lighting devices. In electrical excitation, organic light emitting diodes to produce singlet excitons and three excitons, two number ratio of 1:3. the traditional fluorescent material, light emitting device covers the visible light, good stability, but the traditional fluorescent material only the singlet exciton can be used for light, three excitons 75% in non luminescent mode deactivation, greatly limits the efficiency of the device. In order to improve the luminous efficiency of the device, the phosphorescent material was developed the application in organic light emitting diode. Because phosphorescent materials can use both the singlet exciton and three triplet excitons, phosphorescent materials of organic light emitting devices in quantum efficiency can reach 100%. based on However, the driving stability of blue phosphorescent material device needs to be further improved, and phosphorescent materials containing iridium, platinum and other precious metals due to its expensive devices high preparation cost.TADF (thermally activated delayed fluorescence) materials using both singlet exciton and exciton emission in the three line not containing precious metal case called after the fluorescent materials and phosphorescent materials of the third generation of organic optoelectronic materials, has aroused widespread concern. Among them, the blue TADF material double [4- (9,9- two -9,10- two methyl hydrogen acridine) phenyl] sulfone (DMAC-DPS) in sulfur doped and non doped devices show good luminescent characteristics. This paper mainly studies the characteristics of blue TADF materials based on DMAC-DPS, mainly including the following aspects: (1) study of the non doped devices based on DMAC-DPS, discusses the hole transport layer device, electronic transmission Influence of layer and the thickness of the emitting layer on the device characteristics. The preparation of the structure of ITO/MoO3 (5nm) /mCP (nm 40) /DMAC-DPS (30 nm) /SPPO13 (nm 50) /CsF (1 nm) /Al (150 nm) DMAC-DPS non doped devices, external quantum efficiency and power efficiency of the device is respectively 14.3% and 26.8 LM W-1. I-V by further comparison of characteristics of unipolar carrier device, the device is found holes in the majority carrier, the carrier recombination region near the light emitting layer and electron transport layer interface. (2) based on these non doped devices, in blue luminescent material TBPe DMAC-DPS light-emitting layer doped with different ratio of the system with the structure of ITO/MoO3 (5 nm) /mCP (nm 40) /DMAC-DPS:TBPe (30 nm) /SPPO13 (50 nm) /CsF (nm 1) /Al (150 nm) TADF on the I-V-B device. The sensitized fluorescence properties of TBPe doping concentration on the luminescence devices, density characteristics and electrical efficiency - current photoluminescence spectra characteristics Effect of external quantum efficiency of.DMAC-DPS:1.0%TBPe device is 12.7%, the external quantum efficiency is close to DMAC-DPS non doped devices. The device color (0.15,0.25), compared with DMAC-DPS non doped devices, chroma (0.16,0.27) improved. Further discussed the excited state and evolution of DMAC-DPS:TBPe devices. (3) in order to avoid the effects of a variety of energy loss the mechanism of TADF sensitized fluorescence on the device efficiency of the device, we choose in DMAC-DPS doped green TADF material 2,4,5,6- four (9- carbazole) - isophthalonitrile (4CzIPN) and yellow TADF material 2,3,5,6- four (3,6- two -9- phenyl carbazole) - two of benzene nitrile (4CzTPN-Ph), was prepared with a structure of ITO/MoO3 (5 nm /mCP (nm) 40) /DMAC-DPS:G/YTADF (30 nm) /SPPO13 (nm 50) /CsF (1 nm) /Al (150 nm) of the TADF light emitting devices. Green light devices the maximum external quantum efficiency and the maximum power efficiency were 10.9% and 32.1 LM W-1, yellow light The maximum external quantum efficiency and the maximum power efficiency of the device were 11% LM and 36.6 W-1. in this kind of devices we can keeping high external quantum efficiency, higher concentration range adjustment object materials which also has better device luminous efficiency and luminous color purity. In addition, we also found that compared to and in the main material widely used in CBP, in DMAC-DPS, was about 30 nm blue shift of luminescence of 4CzTPN-Ph, which mainly come from different subject and object material dipole interaction. (4) based on the DMAC-DPS: 4CzTPN-Ph device on the lower 4CzTPN-Ph concentration, preparation structure ITO/MoO3 (5 nm) /mCP (nm 40) /DMAC-DPS:4CzTPN-Ph (30 nm) /SPPO13 (nm 50) /CsF (1 nm) /Al (150 nm) of the white light device. The 0.4%4CzTPN-Ph device has the high external quantum efficiency of 14.7%.0.8%4CzTP N-Ph device (0.29,0.39), chroma is closest to the white and color stability better. DMAC-DPS:0.4%4CzTPN-Ph thin film devices measured by photoluminescence spectroscopy and transient absorption spectra, photoluminescence spectra also found at 550 nm in the light and transient spectra in the delayed luminescence decay model fitting part of its life span is 0.7 s and 2.6 s double index, were similar with the reported DMAC-DPS and 4CzTPN-Ph, excluding the exciplex formation. The influences of the excited state and the evolution principle of DMAC-DPS:TADF devices and TADF devices with the sensitized fluorescence of DMAC-DPS:4CzTPN-Ph devices, the external quantum efficiency of DMAC-DPS devices with almost the same proof of all full exciton the TADF device can effectively use the material object light, reduce the energy loss.

【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN383.1

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