OLED Capping Layer Inkjet Printing Moisture Barrier

The patent uses a composite capping layer structure consisting of an inorganic layer (such as Alq3 or BCP) combined with an organic layer (such as TCTA or NPB). This composite structure leverages the excellent moisture and oxygen barrier properties of the inorganic layer while utilizing the high light extraction efficiency of the organic layer, thereby resolving the contradiction between protection and light output.

The patent optimizes the molecular structure parameters of the organic compounds used in the capping layer. By selecting compounds with specific molecular weights, functional groups, and chemical structures (such as TCTA with its triphenylamine core), the material achieves both high light extraction efficiency and low solubility in inkjet printing solvents, thereby maintaining device lifetime while improving optical performance.

The patent carefully controls the physical and chemical parameters of the organic compounds, including molecular weight, glass transition temperature, and solvent compatibility. These parameter optimizations enable the material to form uniform, smooth films through inkjet printing without developing bumps or hollows, achieving both ease of manufacture and high surface quality.