Light-Defined Reaction Fields via Topochemical Control for Single-Shot Projection Photoprinting

A central challenge in three-dimensional (3D) photoprinting lies in the absence of a deterministic translation from optical fields into volumetric chemical reaction fields. Here, we establish a photoprinting strategy in which light acts not merely as a trigger, but as a programmable input that defines a spatial chemical reaction field enabled by molecular spatial homogeneity and topochemical control. Within this light-defined reaction field, topochemical reactions are spatially confined and propagated along the depth direction, generating continuous reaction gradients that deterministically translate optical projections into 3D chemical transformations. We realize this concept using a large-area ADCA-based single-cocrystalline photoresist film, in which well-defined molecular packing supports efficient cascade reactions. The resulting light-defined spatial reaction field enables low-power (µW), millimeter-scale projection photoprinting, producing 3D nanostructures with a sub-diffraction-limited lateral resolution of 153 nm and an axial resolution of 3.5 nm. By integrating a home-built projection system with computational modeling, arbitrary graphic inputs can be directly compiled into programmable 3D chemical reaction fields and rapidly translated into nanoarchitectures within seconds. These results establish topochemical reaction-field-guided projection photoprinting as a powerful strategy for rapid, high-resolution three-dimensional fabrication in ADCA-based single-cocrystalline photoresists and suggest a broader molecular-design principle for future co-crystalline photoprinting materials.