退火处理对有机电致发光器件性能的影响

发布时间：2018-05-31 13:03

本文选题：有机电致发光器件 + 退火处理　；参考：《重庆师范大学》2015年硕士论文

【摘要】：有机电致发光器件(organic light emitting device,OLED)以其制备工艺简单、轻质便携、可选材料丰富、视角宽、柔性易弯折等优点,在显示和照明领域具有广泛的应用前景,受到越来越多的关注。尽管有机电致发光器件至今已发展近30年,但在单色OLED研究中,蓝光器件在效率,稳定性和寿命等方面仍不及红、绿两色器件。这主要是由于蓝光材料能隙大,选择合适的蓝光材料比较困难所造成的。本论文采用控制温度进行原位退火处理来实现绿光材料Alq3发光光谱蓝移,并从界面势垒,载流子迁移,载流子复合等物理机制等角度,来分析采用退火处理后器件性能变化的原因。本文首先探讨了氧等离子体处理ITO阳极后,对所制备结构为ITO/NPB(50nm)/Alq3(60 nm)/Al(100 nm)标准器件性能的影响。我们使用氧等离子体对ITO阳极进行不同功率(0,40,50,60,70 W)和不同时间(0,5,10,15,20 min)的处理,利用处理后的ITO阳极制备标准器件,并采用keithley2400-PR655测试系统对器件的电压-电流-亮度特性进行测试。研究了标准器件ITO阳极氧等离子体在实验条件允许范围内的最佳处理功率和最佳处理时间。经过氧等离子体处理的ITO阳极,其表面得到彻底清洗的同时,提高了ITO阳极的功函数,降低了空穴的注入势垒,提高了空穴注入率,进而提高了所制备器件的发光效率和亮度。实验证明,当腔室内的压强控制在约80 Pa,清洗功率为70 W时,氧等离子体处理持续15min后所制备的器件性能最好。我们探讨了退火处理对Alq3晶相和光谱的影响。我们制备了ITO/Alq3(60 nm)/NPB(50 nm)和ITO/NPB(50 nm)/Alq3(60 nm)样片,在90,120,130,145,160,180℃下进行90 min的真空原位退火处理,研究其晶相,光致发光谱与透射谱的变化情况。发现随着退火温度的升高,尤其是130℃以上温度Alq3出现结晶现象,出现新晶相,即β-Alq3,导致Alq3的光致发光谱峰值也从未退火处理时的539 nm,逐渐蓝移到503 nm,发生了大约30 nm的蓝移,其透射吸收峰也出现蓝移现象。围绕退火处理对有机电致发光器件性能影响的研究主题,我们制备了标准器件。同样在90,120,130,145,160,180℃下进行90 min的真空原位退火处理,进一步研究了退火处理对有机电致发光器件光电性能的影响。由于退火处理使得Alq3出现新晶相,载流子在有机层内的迁移减弱,整体上呈现随着退火温度升高,器件启亮电压逐渐增大,亮度也随之下降的规律。其中退火温度从130℃到145℃过程中,出现稍稍变化,推测Alq3出现了大部分甚至全部结晶的现象,使得有机层界面出现新的契机,更加适合电子与空穴的迁移。当退火温度达到180℃时,低电压情况下就会出现Al阴极脱落现象,无法测量此温度退火处理后器件的光电性能。但从器件的寿命和稳定性方面考虑,与未进行退火处理的器件相比,退火处理后器件未出现明显发热甚至炸裂的现象。在130℃退火处理后的电流效率达到最大值为2.38 cd/A。同时,器件的电致发光光谱峰值发生约30 nm的蓝移,与结晶后产生β-Alq3的光谱蓝移现象相同。
[Abstract]:Organic electroluminescent devices (organic light emitting device (OLED)) have been widely used in the field of display and lighting, with its advantages of simple preparation technology, portable light quality, rich light quality, wide selectable material, wide angle of view, flexible flexural and so on. The organic electroluminescent device has been developed for nearly 30 years, but in monochromatic O In the LED study, blue light devices are still less than red in efficiency, stability and life expectancy. This is mainly due to the difficulty in selecting the suitable blue light materials because of the large gap in the blue light materials. This paper uses the control temperature to carry out the in-situ annealing treatment to realize the blue shift of the green light material Alq3 luminescence spectrum, and from the interface barrier, The effects of carrier migration, carrier recombination and other physical mechanisms on the performance changes of the devices after annealing are analyzed. First, the effects of the oxygen plasma on the performance of the ITO/NPB (50nm) /Alq3 (60 nm) /Al (100 nm) standard device after the oxygen plasma treatment of the ITO anode are investigated. We use oxygen plasma to carry out the ITO anode. The processing of different power (0,40,50,60,70 W) and different time (0,5,10,15,20 min), using the treated ITO anode to prepare standard devices, and using keithley2400-PR655 test system to test the voltage current luminance characteristics of the device, and study the best treatment of the standard device ITO anodic oxygen plasma in the allowable range of experimental conditions. Power and optimum processing time. The surface of the ITO anode treated by oxygen plasma is thoroughly cleaned, while the work function of the ITO anode is improved, the injection barrier of the cavity is reduced, the hole injection rate is increased, and the luminous efficiency and brightness of the fabricated devices are improved. The experiment shows that the pressure control in the chamber is about 80 Pa, When the cleaning power is 70 W, the performance of the devices prepared by the oxygen plasma treatment for 15min is the best. We discuss the effect of annealing treatment on the crystal phase and the spectrum of Alq3. We have prepared ITO/Alq3 (60 nm) /NPB (50 nm) and ITO/NPB (50 nm) /Alq3 (60 nm) samples, and carried out the vacuum in-situ annealing treatment of 90 min at 90120130145160180 centigrade. The crystal phase, photoluminescence spectrum and transmission spectrum change. It is found that with the increase of annealing temperature, especially the temperature Alq3 above 130 degrees C, the new crystalline phase, that is, beta -Alq3, leads to the peak of photoluminescence of Alq3, which has never been annealed at 539 nm, and gradually blue shift to 503 nm, and the blue shift of about 30 nm has occurred, and its transmission is transmitted and absorbed. We have prepared a standard device for the study of the effects of Annealing on the performance of organic electroluminescent devices. We also performed a 90 min vacuum in-situ annealing at 90120130145160180 C, and further studied the effect of Annealing on the photoelectric properties of the electromechanical generator. The migration of the carrier in the organic layer is weakened. As the annealing temperature increases, the brightness of the device increases gradually and the brightness decreases as the annealing temperature rises. In the process, the annealing temperature varies slightly from 130 to 145, and most of the crystallization of the Alq3 appears. There is a new opportunity for the organic layer interface, which is more suitable for the transfer of electrons and holes. When the annealing temperature reaches 180 degrees C, the Al cathodic loss phenomenon will appear at low voltage conditions. It is impossible to measure the photoelectric performance of the device after the annealing treatment. But considering the life and stability of the device, it is compared with the device that has not been annealed. After annealing treatment, the device has no obvious heat or even crack. The current efficiency after annealing at 130 C reaches the maximum value of 2.38 cd/A., and the peak of the electroluminescent spectrum of the device takes about 30 nm blue shift, which is the same as the blue shift of beta -Alq3 after crystallization.
【学位授予单位】：重庆师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN383.1

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