Research On Organic Light-emitting Device With N-type Doping By RbBr

Organic Light-Emitting Device(OLED) has many advantages such as solid-state, self-luminou, high brightness, wide viewing angle and flexiblity e, so OLED has been regarded as the future display and lighting technology. The OLED industry has been developing very quickly, OLED displays have a large number of applications in mobile phones, mp3, television, medical electronic equipment, automotive electronic devices, OLED lighting technology has also been going into industrial production. Many companies such as Osram, GE already had OLED lighting products. However, there still exist some problems on OLED technology, such as the turn-on voltage is not low enough, the device efficiency is not high enough, the work life is not long enough.One of the effective methods to solve these problems is electrical doping. Electrical doping includes N-type and P-type doping. The P-type doping research has been widely reported, the development is very rapid. However, the development of N-type electrical doping is relatively slowler than the P-type electrical doping, so the N-type electrical doping requires further study. N-type electrical doping can significantly improve the injection of electrons from the cathode to the organic layers. Now main extensive N-type doped materials are alkali metals and their compounds, Li and Cs as the representative of the alkali metal and their compounds are widely used for the N-type doping material, such as LiF, Li2CO3, CS2CO3, CsF and so on. Li atomic size is relatively small, so Li can easily spread into the light-emitting layer and affects the performance; Cs compounds, such as CS2CO3, its deposition temperature (>600°C) is very high, the high evaporation temperature affects the compatibility of electron injection layer and electron transporting layer, and is not conducive to applications in industrial production. Based on the above factors, a new type of N-type dopant material is needed to avoid the above shortcomings. Therefore, after reading a lot of literature and experimental exploration, the RbBr material is used as a new N-type doping material because the Rb atoms has relatively large atomic size and RbBr has relatively low deposition temperature.In this paper RbBr layer and RbBr:Alq3doped layer were developed in OLED. The RbBr modified layer experiment show that after adding the RbBr modified layer OLED device performance has been greatly enhance. In order to do the further research on the RbBr modified layer for improving OLED performance reasons, the experiment produced a single-carrier devices, experiments show that the current characteristics of device with RbBr layer have been greatly improved, because the electron injection has been strengthened and the number of holes and electrons is more balance, so the luminous efficiency of the device is improved. RbBr:of Alq3doped layer experiments use the structure of ITO/MoO3/NPB/Alq3/RbBr:Alq3/Al. The experiments show that adding a modified layer device performance will be very largly increase.In summary, RbBr is an effective n-type dopant to improve the performance of OLED. RbBr can aviod the disadvantage of Li alkali metal compounds and CS2CO3material. RbBr can be used as a novel N-type electrical doping agent material for further research.