Design of Multicarboxylated Phenolic Resin Functionalized With Cinnamic Acid for Quantum Dots Photolithography

Quantum dots (QDs) are essential for next-generation displays, yet their hydrophobic ligands cause poor adhesion to the substrates, thus leading to film detachment during photolithography. To address this, a carboxyl-functionalized phenol-formaldehyde (PF) oligomer was rationally designed and synthesized, in which each structural unit bears a carboxyl group to enable strong interfacial interactions with QD surfaces and underlying substrates, serving as a versatile platform for multifunctional photoresist development. Building on this, cinnamate (CA) groups were further introduced as photoactive crosslinking units and chain-end groups by polycondensation of the PF oligomer with phenylphosphonic dichloride, yielding the multifunctional PFP-CAs. The obtained PFP-CAs with multicarboxylate groups exhibit high viscosity and excellent solubility in the solvent of propylene glycol methyl ether acetate (PGMEA). A QD photoresist (QDPR) formulation was subsequently prepared by dispersing QDs with PFP-CAs in PGMEA, and high-resolution patterns with a feature size down to 5 μm has been achieved, demonstrating that the multicarboxylate architecture effectively overcomes the adhesion limitations of conventional QDPRs. These findings establish PFP-CAs as a promising resin platform for high-resolution QD photolithography, offering a practical and scalable pathway toward the precise color-patterning required in next-generation manufacturing.