Micromate 5: Application Solution for OLED Electronic Material Digestion
1、 Preface
OLED stands for Organic Light Emitting Diode, also known as Organic Electroluminescence Display. OLED belongs to a current type organic light-emitting device. Under the action of an electric field, the holes generated by the anode and the electrons generated by the cathode will move. The holes are injected into the hole transport layer, the electrons are injected into the electron transport layer, and then migrate to the light-emitting layer. When the two meet in the luminescent layer, energy excitons are generated, which excite luminescent molecules and ultimately produce visible light.
The optoelectronic properties of OLED largely depend on the characteristics of the luminescent material.
For anode materials, in order to improve the efficiency of hole injection, high work function and translucency are required. Generally, Au, transparent conductive polymers (such as polyaniline), and ITO conductive glass are used. ITO conductive glass with stable properties is commonly used as an OLED anode material due to its transmittance of over 80% in the wavelength range of 400 nm to 1000 nm and high transmittance in the near ultraviolet region.
For cathode materials, in order to improve the efficiency of electron injection and prolong the service life of the device, it is required to have the lowest possible work function. Typically, single-layer metal cathodes or alloy cathodes made of metals such as Al, Ag, Ca, In, Mg, etc. are used. A barrier layer, such as LiF, CsF, RbF, etc., can also be added between the light-emitting layer and the metal click to form a dual electrode with Al, which can significantly improve the performance of the device.
However, during the production process of OLED, some metal impurities may be introduced, and non emissive metal impurities will become black spots on the OLED display screen, accelerating the oxidation of luminescent components and leading to large-scale screen distortion and black screen phenomena. Usually, metal residues above 400 ppb will affect the luminescence performance.
Currently, ICP-MS method is commonly used to detect residual metal elements in OLEDs. OLED materials are mainly tightly structured polymer materials that cannot be pre treated using traditional digestion methods. This experiment used the Boao Micromate 5 microwave digestion instrument to digest OLED luminescent materials. This method is fast and requires less acid, which is beneficial for accurate and rapid determination of trace metal elements in the future.
2、 Instruments and reagents
Bo Ao Micromate 5 Microwave Digestion Instrument, Analytical Balance;
OLED electronic material sample, nitric acid, NPM-UHM-100 (N-methylpyrrolidone) organic solvent.
3、 Test method
1. Weigh 0.1 g of the sample and place it at the bottom of the digestion tank, being careful not to hang it on the wall;
2. Add 6-8 mL of nitric acid as a digestion agent and assemble the digestion tank;
3. Dissolve the sample at a temperature of 200 ℃ for 1800 seconds;
4. After the digestion is completed and cooled to room temperature, remove the digestion tank, open it in a fume hood, and adjust the volume for subsequent analysis.
4、 Results and Discussion
The experiment used the Boao Micromate 5 microwave digestion instrument to digest 0.1 g of OLED electronic material. After digestion, the sample was clear and transparent without precipitation.
