Polymerization‐Confined Crystallization Enables Multicolor Perovskite Nanocomposites via Femtosecond Laser Direct Writing

Abstract Perovskite quantum dots (PQDs) have emerged as promising candidates for advanced optoelectronic applications. However, integrating them into functional microdevices requires precise patterning techniques. While femtosecond (fs) laser direct writing offers sub‐diffraction‐limited resolution and 3D functionality, its direct patterning of PQDs may result in lattice overheating and material decomposition. To resolve this dilemma, a “ Polymerization‐Confined Crystallization ” strategy is proposed, actualized through a specially designed Perovskite‐Monomer Composite Precursor ( PMCP ). In this approach, fs laser direct writing induces two‐photon polymerization within the PMCP solution, enabling monomers to polymerize into a stable network. Subsequently, PQDs crystallize in situ and are confined within the polymer network. This process ensures that PQDs are formed via a polymerization‐confined mechanism, rather than through direct and potentially damaging interaction with the perovskite precursors. This technique achieves a sub‐diffraction‐limited resolution of 120.3 nm and enables the fabrication of multicolor high‐resolution perovskite‐polymer composite patterns. Furthermore, this method offers a significantly simpler approach to fabricating 3D multicolor microstructures compared to direct fabrication techniques within inorganic solid‐state materials. Due to the encapsulation of PQDs within the polymer matrix, the resulting structures exhibit improved stability. This innovative approach enables PQDs applications in high‐resolution patterning, data storage, anti‐counterfeiting encryption, and 3D displays.