| Summary: | 碩士 === 義守大學 === 電子工程學系 === 92 === In organic materials, the mobility of the holes(μp , 10-4 cm2/Vs)) are much fast than the electrons(μn , 5x10-6 cm2/Vs). The extra holes will decrease the efficiencies of the light emission. Therefore, the most important issue is to balance the amount of the holes and electrons in the organic light emitting diode (OLED). There are two common ways to achieve it. First is to increase the electrons mobility. Second is to decrease the holes mobility. In this work, we decrease the holes mobility to improve the combined efficiency between the holes and electrons.
We inserted a NPB：Alq3 mixed layer between these two NPB and Alq3 layers to decrease the holes mobility and improve the combined efficiency between the holes and electrons. After inserting the NPB：Alq3 layer, the current density of the device( ITO/ MTDATA（15 nm）/ NPB[（60-X）nm]/NPB：Alq3 (Y wt%)(X nm) / Alq3（60 nm）/ LiF(0.7 nm)/ Al(180 nm)) is decreased obviously. This result suggests that NPB：Alq3 layer could delay the holes mobility. The optimum concentration in our device is 30 wt% while the total thickness is 30nm. Finally, we also discuss the possibility of emission light in the NPB：Alq3 layer and the applications of red OLEDs in the future.
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