QLED Electron Transport Layer Cleaning for Impurity Removal

The patent applies preliminary action by performing a pre-treatment step on the substrate before depositing the electron transport layer. The substrate undergoes cleaning and activation treatments to remove contaminants and create a clean surface, preventing impurity introduction at the source rather than attempting to remove them afterward. This preliminary preparation ensures the electron transport layer is formed on a contaminant-free surface, thereby improving service life without compromising layer formation.

The patent converts the potentially harmful effect of common manufacturing impurities into a benefit by using a selective cleaning approach. The cleaning process is designed to remove specific organic contaminants and moisture that cause degradation, while preserving the functional morphology of the electron transport layer. By selectively eliminating harmful impurities through controlled thermal treatment and solvent vapor exposure, the method transforms the manufacturing challenge into an opportunity to enhance both luminous efficiency and device reliability.

The patent applies local quality by using a solution with specific local chemical properties - high polarity solutes that selectively interact with impurity molecules rather than the electron transport material. The solution's polarity is locally optimized to match the impurity characteristics while being incompatible with the electron transport material's solubility requirements. This selective local interaction allows impurity removal through differential solubility, where the high polarity solute binds to and extracts polar impurities while leaving the non-polar or less polar electron transport material intact and undissolved.

The patent applies parameter changes by carefully controlling the polarity parameter of the cleaning solution. The solution uses solutes with polarity values specifically selected to be higher than the electron transport material's polarity threshold, creating a polarity gradient that favors impurity extraction. By adjusting the solution's polarity parameters (through solvent selection and concentration control), the method achieves optimal impurity removal while maintaining the structural integrity of the electron transport layer, as the material's solubility is not reached at the controlled solution parameters.