Improved Property in Inverted Bottom-emission Organic Light-emitting Diodes Using 8-Hydrozyquinolinolatolithium Layer
We demonstrate inverted bottom-emission organic light-emitting diodes (IBOLEDs) using 8-Hydroxyquinolinolatolithium (Liq) as an electron injection layer and an indium-tin-oxide coated glass substrate directly as cathode. The performances of devices with different thickness of Liq were investigated. Experiment results show that the efficiency of device with 1-nm-thick Liq is four times higher than that without Liq. The turn-on voltage of devices decreased from 20 to 9V as the 1-nm-thick Liq was employed. Liq itself is an organic material which has a very similar electronic structure to Alq3. Therefore the energy level mismatch would be minimal and made the number of injected electrons and holes balance, and it significantly improves the device properties by inserting Liq electron injection layer between the emitting layer and cathode. At the same time, we also demonstrate IBOLEDs using LiF as an electron injection layer and an indium-tin-oxide coated glass substrate directly as cathode. We found that the device using Liq as an electron injection layer is less sensitive to the Liq thickness than using LiF in efficiency. This property of Liq would be very important in the mass production. The difference may be attributed to the fact that Liq is an organic semiconductor and LiF an insulator, it can only be used when deposited as an ultra-thin layer. Our experimental results support the assumption that free lithium released from lithium quinolate is responsible for the improved device performance, and this release is more effective than that observed in devices with LiF. The results prove that Liq layer is also suitable for electron injection in IBOLEDs with an indium-tin-oxide coated glass substrate directly as cathode. This IBOLEDs can be integrated readily with the n-channel of the α-Si TFT backplane, which is proved to be useful in manufacturing Active-matrix organic light emitting device with high-power efficiency and long device stability for future large-size OLEDs display applications.
J.F.Li W.L.Chang F.J.Zhang
School of Physical Science and Technology,Lanzhou University,Lanzhou 730000,China;School of Mathemat School of Mathematics,Physics & Software Engineering Lanzhou Jiaotong University,Lanzhou 730070,Chin School of Physical Science and Technology,Lanzhou University,Lanzhou 730000,China
国际会议
Progress in Electromagnetics Research Symposium 2009(2009年电磁学研究新进展学术研讨会)(PIERS 2009)
北京
英文
1068-1072
2009-03-23（万方平台首次上网日期，不代表论文的发表时间）