Synergistic Engineering of Crystalline Organoantimony‐Selenite Clusters Enabling Water‐Developable, High‐Sensitivity Nanopatterning

Comprehensive Summary The development of photoresists that combine high‐sensitivity with environmental benignity is essential for advancing next‐generation nanofabrication technologies. Herein, we present a molecular engineering strategy wherein selenite ligands are employed to assemble a series of dinuclear phenylantimony(oxo)‐selenite clusters (designated as α , β , γ ) with precisely tunable phenyl group densities, ranging from four to eight per cluster. A synergistic sensitivity mechanism is elucidated: the high‐atomic‐number ( Z ) inorganic core, comprising Sb and Se, functions as an efficient energy absorption antenna, while the surrounding shell of labile Sb–C bonds gives a high density of reactive initiation sites. Among the series, cluster γ exhibits optimal lithographic performance, achieving complete solubility switching at 26 μC·cm –2 , while maintaining sub‐nanometer film smoothness. Notably, all resists are fully developable in pure water, underscoring their compatibility with environmentally sustainable processing. This work establishes a synergistic core‐shell design principle for the development of high‐performance, eco‐friendly photoresists.