高显色指数白光有机发光二极管的研究
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摘要
具有高显色指数的白光有机发光二极管是有机发光二极管中非常重要的一类,在近几年来受到广泛的重视。本文围绕高显色指数的白光有机发光二极管是有机发光二极管进行了一些列的研究。
采用非掺杂技术制备了高显色指数白光有机发光二极管,器件最大亮度为19096 cd/m2,最大电流效率为4.12 cd/A,器件的发光光谱在8 V到12 V之间色坐标稳定,都在白光等能点(0.333,0.333)附近,白光的显色指数在80.9~90.2之间变化,相关色温在5804 K~6714 K间变化。由于器件中没有激子阻挡层,所以器件的效率比较低。为了提高器件效率,我们进一步在器件中引入Bphen作为激子阻挡层,变化器件结构。提高了器件的效率,得到的器件的最大电流效率为5.17 cd/A,最大功率效率为3.27 lm/W。在7 V到12 V之间色坐标都稳定在白光等能点附近。显色指数都在90以上,相应的相关色温为在5112 K~6989 K之间。
全部利用激基复合物的发射制作了高显色指数白光有机发光二极管,由于激基复合物的光谱较宽,所以获得的白光光谱覆盖范围比较宽,半高宽大于270 nm。得到的器件在8 V到14 V之间,发光的色坐标始终在白光等能点附近,显色指数全部在92以上,相关色温在3376 K到6571 K之间变化。器件的起亮电压大约为5 V,最大亮度为610 cd/m2,最大效率为0.38 cd/A。
首先开发了一种双母体结构,这种双母体结构能够提高多种红光和绿光掺杂剂染料的器件的效率。相对于传统的以Alq3为母体的器件,采用双母体结构的器件对于以DMQA为掺杂剂的绿光器件,效率提高了54%;而对于以DCJTB为掺杂剂的红光器件,效率提高了104%。接下来利用开发的双母体结构制作了高效高显色指数的WOLED,这种WOLED从8 V到14 V所有的色坐标都在白光等能点附近,色温在5000 K到6000 K之间,显色指数全部在90以上。颜色质量符合高要求的白光照明应用。器件的最大亮度在14 V时达到,为27853 cd/m2;最大电流密度在7.5 V时达到,为9.58 cd/A;最大效率比对比器件提高了73.6%。
The white organic light-emitting diode (OLED) with high color rendering index (CRI) is an important category in OLEDs. It has drawm much attention in recent years. In this thesis, a series of studies have done on the white OLEDs with high CRI.
We have fabricated the white OLED with high CRI using undoped technology. The white behaves a maximum luminance of 19096 cd/m2 and a current efficiency of 4.12 cd/A, as well the CIE-1931 xy coordinates shift slightly under biases from 8 to 12 V. A CRI of 90.2 and the corresponding CCT of 5804 K were obtained as well. Because these are no exciton blocking layer in the device, the efficiency is low. To enhance the efficiency, we add the exciton blocking layer into the device. A white OLED with a maximum brightness of 21010 cd/m2 and a current efficiency of 5.17 cd/A were observed, respectively. as well the CIE coordinates locate near the point (0.333, 0.333) under biases from 7 to 12 V. A CRI of 91.2 and the corresponding CCT of 6145 K were obtained.
A type of white OLED using four exciplexes was fabricated. A very broad white EL band with half-width of about 270 nm was obtained by four emission bands that strongly overlap. No monomer emission is responsible for the EL. A CRI of 94.1, CIE coordinates of (x=0.33, y=0.35), and CCT of 5477 K were obtained at bias voltage of 10 V.
Firstly, we investigated a type of cohost system. The cohost system can be used in many different red and green dopants. The maximum current efficiencies are increased by 54% and 104% for green and red devices comparing to the conventional Alq3 single host devices. Then we fabricated a white OLED with high CRI using the cohost system above. As a sesult, a maximum brightness of 27853 cd/m2 and a current efficiency of 9.58 cd/A were observed, respectively. The maximum efficiency is increased by 73.6% compared to the control device. The CIE coordinates shift from (0.3432, 0.3397) to (0.3243, 0.3218), the CCT varies from 5035 K to 5915 K and all the CRIs exceed 90 under the biases from 8 to 14 V.
采用非掺杂技术制备了高显色指数白光有机发光二极管,器件最大亮度为19096 cd/m2,最大电流效率为4.12 cd/A,器件的发光光谱在8 V到12 V之间色坐标稳定,都在白光等能点(0.333,0.333)附近,白光的显色指数在80.9~90.2之间变化,相关色温在5804 K~6714 K间变化。由于器件中没有激子阻挡层,所以器件的效率比较低。为了提高器件效率,我们进一步在器件中引入Bphen作为激子阻挡层,变化器件结构。提高了器件的效率,得到的器件的最大电流效率为5.17 cd/A,最大功率效率为3.27 lm/W。在7 V到12 V之间色坐标都稳定在白光等能点附近。显色指数都在90以上,相应的相关色温为在5112 K~6989 K之间。
全部利用激基复合物的发射制作了高显色指数白光有机发光二极管,由于激基复合物的光谱较宽,所以获得的白光光谱覆盖范围比较宽,半高宽大于270 nm。得到的器件在8 V到14 V之间,发光的色坐标始终在白光等能点附近,显色指数全部在92以上,相关色温在3376 K到6571 K之间变化。器件的起亮电压大约为5 V,最大亮度为610 cd/m2,最大效率为0.38 cd/A。
首先开发了一种双母体结构,这种双母体结构能够提高多种红光和绿光掺杂剂染料的器件的效率。相对于传统的以Alq3为母体的器件,采用双母体结构的器件对于以DMQA为掺杂剂的绿光器件,效率提高了54%;而对于以DCJTB为掺杂剂的红光器件,效率提高了104%。接下来利用开发的双母体结构制作了高效高显色指数的WOLED,这种WOLED从8 V到14 V所有的色坐标都在白光等能点附近,色温在5000 K到6000 K之间,显色指数全部在90以上。颜色质量符合高要求的白光照明应用。器件的最大亮度在14 V时达到,为27853 cd/m2;最大电流密度在7.5 V时达到,为9.58 cd/A;最大效率比对比器件提高了73.6%。
The white organic light-emitting diode (OLED) with high color rendering index (CRI) is an important category in OLEDs. It has drawm much attention in recent years. In this thesis, a series of studies have done on the white OLEDs with high CRI.
We have fabricated the white OLED with high CRI using undoped technology. The white behaves a maximum luminance of 19096 cd/m2 and a current efficiency of 4.12 cd/A, as well the CIE-1931 xy coordinates shift slightly under biases from 8 to 12 V. A CRI of 90.2 and the corresponding CCT of 5804 K were obtained as well. Because these are no exciton blocking layer in the device, the efficiency is low. To enhance the efficiency, we add the exciton blocking layer into the device. A white OLED with a maximum brightness of 21010 cd/m2 and a current efficiency of 5.17 cd/A were observed, respectively. as well the CIE coordinates locate near the point (0.333, 0.333) under biases from 7 to 12 V. A CRI of 91.2 and the corresponding CCT of 6145 K were obtained.
A type of white OLED using four exciplexes was fabricated. A very broad white EL band with half-width of about 270 nm was obtained by four emission bands that strongly overlap. No monomer emission is responsible for the EL. A CRI of 94.1, CIE coordinates of (x=0.33, y=0.35), and CCT of 5477 K were obtained at bias voltage of 10 V.
Firstly, we investigated a type of cohost system. The cohost system can be used in many different red and green dopants. The maximum current efficiencies are increased by 54% and 104% for green and red devices comparing to the conventional Alq3 single host devices. Then we fabricated a white OLED with high CRI using the cohost system above. As a sesult, a maximum brightness of 27853 cd/m2 and a current efficiency of 9.58 cd/A were observed, respectively. The maximum efficiency is increased by 73.6% compared to the control device. The CIE coordinates shift from (0.3432, 0.3397) to (0.3243, 0.3218), the CCT varies from 5035 K to 5915 K and all the CRIs exceed 90 under the biases from 8 to 14 V.
引文
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