| Organic light emitting diode (OLED) has been paid more and more attention due to its excellent performance, and has been applied to all kinds of products.It is composed of thin film structure, which is composed of organic materials between positive and negative electrodes. It has the advantages of self luminous, full color, simple structure, wide viewing angle, fast response, low driving voltage and low energy consumption. Especially flexible organic light emitting diode (FOLED) is more thin and light, the impact is known as the "dream display", and with the development of TFT-OLED technology, it has become a new generation of development trend.Indium tin oxide (ITO) is a traditional material used as a transparent electrode for OLED. However, the equipment of ITO film deposition is expensive, the production cost is high, and the resistance of the film is high, and the transmission rate is lowwhen it is fabricated in a flexible substrate. And ITO has a brittle and poor adhesion between the substrate, the film will be broken in the bend, so that the devices fail. Ag is one of the best conductive metals, and has excellent ductility. MoO3 has relatively low evaporation temperature and excellent hole transport capacity. In this paper, we use Ag, MoO3 to make metal, dielectric film, and replace ITO as OLED anode, which can be used in the field of flexible devices, etc. This paper mainly study the following two parts:I.The nano thickness of metal/dielectric/metal (Ag/MoO3/Ag) film is prepared by vacuum thermal evaporation, and the transmittance of different structures is studied.The device structure is Ag/MoO3/Ag/MoO3 (10 nm)/NPB (40 nm)/Alq3 (60 nm)/LiF (1 nm) /Al (150 nm). Compare of the voltage and current density, voltage luminance and spectral characteristics of the device. The results show that the device performance with the structure of Ag/MoO3/Ag 20/20/10 (nm) is better. At a driving voltage for 11 V, its brightness to 18421 cd/m2, the current efficiency for 2.45 cd/A; And because of the micro cavity effect in the device, the EL spectrum is blue shifted, and the half height width becomes narrow. But considering the electrode transmittance at the 530 nm is only 17%, so by the conversion the device actual brightness is higher than ITO electrode device. The Ag/MoO3/Ag stack is relatively simple and has a certain application prospect in the optimization of the OLED device.II.The transmittance of the Ag/MoO3/Ag electrode limits the performance of OLED device, and the transmittance of the film systemis needed to improve.Through literature research, it is found that the properties of the substrate can be changed by the SAM layer, which can change the law of the Ag layer, so that the Ag layer has a very high transmission rate and conductivity in a very thin case. The photoelectric properties of MPTMS/Ag/MoO3 composite electrode are studied with the change of MoO3. By optimizing the thickness of each layer of MPTMS/Ag/MoO3, when the structure is MPTMS/Ag (8 nm)/MoO3 (30 nm), the transmission rate of the 520 nm is 75%, the surface resistance reaches 3.78 Ω/sq. With MPTMS/Ag (8 nm)/MoO3 (30 nm) as the electrode making OLED devices, the highest brightness reached 37036 cd/m2, the current efficiency of 4.5 cd/A, and the driving voltage is very low. the driving voltage when the brightness is 100 cd/m2 reaches as low as 2.6 V. The improvement of the device performance is mainly due to the reduction of the hole injection barrier. Then, flexible OLED devices are fabricated on the PET substrate, device performance and the glass substrate devices differ greatly, because of poor surface hydrophilicity of PET, hydroxyl number less, and the device performance is poor. In the future, we can enhance the device performance by increasing the hydrophilicity of PET. The optimized MPTMS/Ag/MoO3 electrode is a simple and feasible method to achieve the device with low drive and high brightness.The lifetime of devices depends greatly on the device package quality, so the detection method of the package quality is of great significance to the optimization of the package. In this study, we theoretically study the feasibility of Ca thin film electrical method to detect encapsulated water permeability, and use the water permeability of the encapsulation method in the laboratory.The water permeability of the package in the experiment is 7.164 ·10-6g/m2·h.The test precision of the electrical method of Ca thin film can meet the requirements of the device, and can be applied in various kinds of packaging methods, and can be easily implemented in the experiment process. |
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