| Quantum dot LEDs(QLED) because of its spontaneous, low energy consumption, high color purity, people are most concerned about the next generation of lighting and display technologies. But it remains on the QLED study is still mainly in the laboratory, the efficiency and lifetime of devices has been hampering the QLED pace of industrialization. Inefficient devices mainly due to injection of holes and poor transmission efficiency, resulting in unbalanced transport of carriers of diseases. QLED devices currently on the other hand are using ITO as the electrodes of the device, and PEDOT:PSS because of its high conductivity is also widely used as hole transport material. But because of the PEDOT:PSS acid and water absorption of the materials themselves have, long-term placement of ITO electrode corrosion affecting the life of the device. In order to effectively address these issues, researchers began to look for a new hole transport materials to replace or modify PEDOT:PSS, transition metal oxides(nickel oxide, molybdenum oxide and vanadium oxide, tungstic oxide, etc) are the most widely studied and achieved some results. Tungsten oxide in particular due to its high transmittance, much merits function and drug-free is the most impressive. But these oxide films prepared by means of basic thermal deposition or magnetron sputtering, costly, is not conducive to the future of industrial development.This paper focuses on solution synthesis of tungsten oxide in application of quantum dot light emitting diode devices to begin. Using different synthetic method for preparation of tungsten oxide nano-particles, and by changing the structure of the mixed-doped tungsten oxide by means of applied QLED devices improve hole-transport capacity of the device, carrier transport process is balanced, so performance and life is greatly improved. The main innovation of this paper can be summarized into the following two parts:(1) Synthesis of tungsten oxide by sol-gel method, and the four different types of device structure is designed to optimize the QLED devices, Eventually, we adopted tungsten oxide /PEDOT:PSS this two-tier structure of as hole injection layer, based on tungsten oxide process conditions such as speed, concentration of exploration, ultimately makes our tungsten oxide optimize device performance has been greatly improved, maximum brightness can reach 41000cd/m~2, maximum efficiency for the 15.1cd/A, 18.25lm/W maximum power efficiency, and optimize device maximum external quantum efficiency(EQE) reached 10.48%, the performance indicators of the relative standard has increased about 30%. And because the addition of tungsten oxide layer, PEDOT:PSS itself has acidic and easily absorb water and isolate the ITO electrode, tungsten oxide itself has very good stability, so we optimized the life expectancy of the device about 20 times higher than standard devices.We use water solution synthesis of tungsten oxide nano-particles, and transmission electron microscopy(TEM), x-ray diffraction(XRD) analysis and synthesis of tungsten oxide nanoparticle shape uniform, without high temperature annealing process. Tungsten oxide and PEDOT:PSS in accordance with a definite volume mixing ratio, quantum dots and then applied to the green light emitting diode devices, device performance is greatly improved. Then we went to I-V testing devices, and making a single hole, found the addition of tungsten oxide improves the hole injection/transport abilities of the device. |
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