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.