Simultaneous Engineering of Cation Disorder and Morphology of Molecular-ink Derived AgBiS2 Phothocathodes for Solar Water Splitting

Abstract

This study introduced a strategy based on coordination chemistry for the simultaneous control of cation disorder and morphological refinement in ternary chalcogenide AgBiS2 thin films. Cation disorder, a key parameter influencing optoelectronic properties such as light absorption, was effectively controlled by manipulating metal–ligand interactions within an n-butyl dithiocarbamate (DTC)-based molecular ink system. To further modulate crystallization kinetics, urea was incorporated as a cost-effective and environmentally benign Lewis base additive. Thermodynamic calculations and binding energy analyses revealed that urea preferentially coordinated with Bi3+ cations, thereby suppressing premature nucleation and promoting the growth of large and uniform grains without disrupting the DTC–metal coordination framework. This dual-control strategy enabled the fabrication of high-quality AgBiS2 thin films with enhanced optical absorption and reduced grain boundary recombination, resulting in the first AgBiS2-based photocathodes for photoelectrochemical water splitting.