Ink Composition for Organic Semiconductor Uniformity

The patent changes the physical parameters of the solvent system by selecting specific combinations of hydrophilic solvents (e.g., alcohols, glycols) and hydrophobic solvents (e.g., aromatic hydrocarbons, halogenated hydrocarbons) with controlled solubility parameters. This parameter optimization ensures the ink maintains homogeneity during storage while providing controlled drying characteristics for uniform film formation.

The patent uses a composite solvent system comprising multiple components with different hydrophilicity. The specific combination of hydrophilic and hydrophobic solvents creates a synergistic effect where the hydrophilic solvent ensures good solubility of the organic semiconductor material while the hydrophobic solvent controls evaporation rate, achieving both storage stability and uniform film thickness.

The patent segments the evaporation process into distinct stages by using solvents with different volatility. The hydrophobic solvent evaporates first providing a controlled initial drying phase that ensures uniform film formation, followed by complete evaporation of the hydrophilic solvent phase, eliminating residual solvent while maintaining film thickness uniformity.

The patent exploits phase transitions of the solvent components during drying. The hydrophobic solvent transitions from liquid to vapor first due to its higher volatility, establishing uniform film thickness. Subsequently, the hydrophilic solvent completes the evaporation process, ensuring no residual solvent remains in the final film while maintaining the achieved uniformity.