Unravelling the Effect of Sulfur Precursors on Metal Coordination and Optical Properties in Zn _1‐x Cd _x S Alloyed Nanocrystals

Abstract Colloidal ternary alloyed semiconductor nanocrystals (NCs) have garnered significant attention due to their solution processability and composition‐tunable optoelectronic properties. The precise control over the composition and optical characteristics of ternary alloyed NCs remains a critical challenge. Herein, a one‐pot synthesis strategy is reported for monodisperse Zn 1‐x Cd x S NCs (x = 0.1–0.4) employing two different sulfur precursors (sulfur powder or N, N’‐diphenylthiourea (DPTU)) in conjunction with L‐type (oleylamine, OLA) and X‐type (oleic acid, OA) ligand systems. Structural characterization reveals that both sulfur sources yield NCs with nearly crystalline phases, similar average particle sizes, and spherical morphology, regardless of Zn/Cd ratios. However, photoluminescence (PL) analysis demonstrates a composition‐dependent spectral shift from the blue region to the red region. DPTU‐derived NCs exhibit a 20 nm additional redshift compared to sulfur powder counterparts at high Zn content (x = 0.1). X‐ray photoelectron spectroscopy (XPS) deconvolution identifies a slight shift in Zn 2p 3/2 binding energy for DPTU‐derived NCs, while solid‐state 67 Zn NMR spectra display distinct local chemical structure, collectively indicating sulfur precursor‐induced modulation of Zn coordination environments. These findings elucidate the critical yet overlooked role of sulfur precursor in modulating metal chemistry coordination during alloyed NCs growth.