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中国科学院长春应用化学研究所高分子物理与化学国家重点实验室, 吉林长春130022
纸质出版日期:2000-8-30,
收稿日期:2000-6-12,
修回日期:2000-8-1,
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秦大山, 李德成, 王言, 张吉东, 谢志元, 王广, 王利祥, 闫东航. 发光层的形态结构对电致发光器件性能影响的研究[J]. 发光学报, 2000,21(3): 243-246
QIN Da-shan, LI De-cheng, WANG Yan, ZHANG Ji-dong, XIE Zhi-yuan, WANG guang, WANG Li-xiang, YAN Dong-hang. Effects of the Morphologies and Structures of Light-emitting Layers on the Performance of Organic Electroluminescent Devices[J]. Chinese Journal of Luminescence, 2000,21(3): 243-246
秦大山, 李德成, 王言, 张吉东, 谢志元, 王广, 王利祥, 闫东航. 发光层的形态结构对电致发光器件性能影响的研究[J]. 发光学报, 2000,21(3): 243-246 DOI:
QIN Da-shan, LI De-cheng, WANG Yan, ZHANG Ji-dong, XIE Zhi-yuan, WANG guang, WANG Li-xiang, YAN Dong-hang. Effects of the Morphologies and Structures of Light-emitting Layers on the Performance of Organic Electroluminescent Devices[J]. Chinese Journal of Luminescence, 2000,21(3): 243-246 DOI:
详细研究了沉积在Poly(9-vinylcarbazole)(PVK)薄膜上的8-羟基喹啉铝(Alq
3
)薄膜的形态结构对电致发光器件ITO/PVK/Alq
3
/Mg-Ag性能的影响.研究结果表明:发光层(Alq
3
层)的表面形貌极大地影响发光层和金属阴极的接触面积
从而影响器件的电流电压特性.发光层的表面越均匀连续
发光层和金属阴极的接触面积就越大
通过器件的电流就越大.在三种条件的器件中
基底温度为438K时制备的Alq
3
薄膜所对应的器件的量子效率最高
298K制备的器件的效率次之
77K制备的器件的效率最差.
Organic electroluminescent devices (OLEDs) have been intensively investigated since the first efficient device was demonstrated.Although there are some studies about the dependence of the performance of OELDs on the morphologies and structures of organic thin films
similar studies on Alq
3
have not been reported.In this paper
organic electroluminescent devices with a structure of ITO/Poly (9-vinylcarbazole)/tris(8-hydroxyquinoline)aluminum(Alq
3
)/Mg:Ag are fabricated at different substrate temperature(77K
298K
and 438K)during Alq
3
deposition.It is found that the surface morphologies of Alq
3
thin films greatly affect the
I-V
characteristics of the devices by the contact area between metal cathode and light-emitting layer.The more uniform Alq
3
film is the larger contact area is
and the greater current is obtained.There is a decrease in the uniformity and smoothness of the Alq
3
thin films on PVK films in the order of S
298
>
S
438
>
S
77
.Accordingly
at the same bias voltage
current through the device increases in the order of I
77
<
I
438
<
I
298
.There is a increase in the quantum efficiencies of the devices in the order of η
77
<
η
438
<
η
298
.We attribute this to different structures of Alq
3
thin films.It is confirmed by transmission electron microscopy that the film deposited at 77K consists of polycrystalline grains
and the ones deposited at 298K and 438K are both amorphous.Crystallization can induces lower quantum efficiency than the glassy state does
which answers for the lowest quantum efficiency obtained at 77K. Despite the same glassy state
the quantum efficiency of the film deposited at 438K is higher than that of the film deposited at 298K
which results from the reduction of impurities and defects in the film deposited at 438K.Additionally
photoluminescence measurements testify that there is a increase in photoluminescence efficiencies of Alq
3
films on quartz substrates in the order of E
77
<
E
298
<
E
438
which is consistent with the above conclusions.In summary
by controlling the morphology and structure of Alq
3
film
we can not only improve the quantum efficiency of device
but also reduce the current of device(equal to reduce Joule heat).Hence
it is a new method to improve the performance of device:controlling the condensation state of organic film by substrate temperature.
基底温度形态结构电流密度量子效率
substrate temperaturemorphology and structurequantum efficiencycurrent density
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