MoO2 Sputtering Targets for OLED Work Function Matching
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Solution Overview
Problem
Current sputtering target materials like ITO and zinc-doped ITO have a work function mismatch with the desired light emitting function in organic light-emitting diodes, limiting their performance.
Innovation Solution
High purity MoO2 powder is produced by reducing ammonium molybdate or molybdenum trioxide using hydrogen in a rotary or boat furnace, followed by consolidation into discs or plates, which are then used as sputtering targets to deposit thin films with improved electrical, optical, and surface properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO or zinc-doped ITO sputtering target materials are used, then transparency and conductivity can be achieved, but the work function does not match well with the desired light emitting function
Solution Approach 1:
The invention changes the material composition parameter by using molybdenum dioxide (MoO2) instead of indium-tin oxide (ITO) or zinc-doped ITO. This material substitution fundamentally alters the work function parameter to better match the light emitting function requirements in OLED applications
Solution Approach 2:
The invention uses composite material approaches by combining MoO2 with other materials such as tungsten oxide (WO3) or vanadium oxide (V2O5) to create multi-component sputtering targets that achieve both the desired work function and optical properties for OLED applications
2Manufacturing precision
If high purity MoO2 powder is produced by reduction of ammonium molybdate or molybdenum trioxide using hydrogen, then high purity MoO2 can be obtained, but multiple processing steps are required
Solution Approach 1:
The invention performs preliminary action by pre-calculating and optimizing the reduction temperature profile and hydrogen flow rates before the actual reduction process. This preliminary preparation ensures that the reduction reaction proceeds efficiently to produce high purity MoO2 while minimizing the need for additional purification steps
Solution Approach 2:
The invention utilizes phase transitions in the reduction process, where ammonium molybdate or molybdenum trioxide undergoes controlled phase changes during hydrogen reduction to form MoO2. By controlling the temperature and atmosphere, the phase transition is optimized to directly produce high purity MoO2 powder with minimal impurities
3Manufacturing precision
If consolidation of MoO2 powder by press/sintering, hot pressing, and/or HIP is used to make discs or plates, then near theoretical density can be achieved, but high pressure and temperature conditions are required
Solution Approach 1:
The invention uses composite material approaches by combining MoO2 powder with small amounts of other metal oxides or sintering aids that lower the sintering temperature. These composite formulations enable achieving near theoretical density at reduced temperatures compared to pure MoO2 sintering
Solution Approach 2:
The invention changes the pressure and temperature parameters by using hot isostatic pressing (HIP) instead of conventional sintering. HIP applies high pressure in a controlled atmosphere at elevated temperatures, enabling densification at lower temperatures than traditional sintering methods while achieving near theoretical density
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The MoO2 thin films exhibit properties comparable or superior to ITO and zinc-doped ZnO, enabling their use in OLEDs and other electronic devices with enhanced transparency, conductivity, and surface roughness.
Implementation Method 1
reduction of ammonium molybdate or molybdenum trioxide using hydrogen as the reducing agent
Implementation Method 2
The MoO2 disc, slab, or plate form is sputtered on a substrate using a suitable sputtering method
Data Source
AI summary
The invention relates to high purity MoO2 powder by reduction of ammonium molybdate or molybdenum trioxide using hydrogen as the reducing agent in a rotary or boat furnace. Consolidation of the powder by press/sintering, hot pressing, and/or HIP is used to make discs, slabs, or plates, which are used as sputtering targets. The MoO2 disc, slab, or plate form is sputtered on a substrate using a suitable sputtering method or other physical means to provide a thin film having a desired film thickness. The thin films have properties such as electrical, optical, surface roughness, and uniformity comparable or superior to those of indium-tin oxide (ITO) and zinc-doped ITO in terms of transparency, conductivity, work function, uniformity, and surface roughness. The MoO2 and MoO2 containing thin films can be used in organic light-emitting diodes (OLED), liquid crystal display (LCD), plasma display panel (PDP), field emission display (FED), thin film solar cell, low resistivity ohmic contacts, and other electronic and semiconductor devices.