Generalized water-processed metal chalcogenide complexes: synthesis and applications

Metal chalcogenide complexes (MCCs) have attracted considerable attention recently due to their high solubility in polar solvents, low-temperature decomposition to metal chalcogenide films, and service as ligands for colloidal nanocrystals (NCs). However, most of the MCCs were typically synthesized in the highly toxic and explosive hydrazine (denoted as hydrazine-MCCs), severely restricting the wide applications of MCCs. Here we present a versatile and environmentally benign water-based solution method for the preparation of various MCCs (denoted as water-MCCs) through directly dissolving a series of bulk V₂VI₃ chalcogenides (V = Sb, As and VI = S, Se, Te) in water with the presence of (NH₄)₂S at room temperature and ambient atmosphere. We further show that such water-MCCs can be readily processed into corresponding semiconducting thin films upon mild thermal treatment and then be extended to fabricate compositionally controlled semiconductor alloys with tunable band gaps (i.e., Sb₂(S_1-x,Se_x)₃, 0 ≤ x ≤ 1) through simple control of substrate temperature. Furthermore, we present that our water-MCCs, especially for Sb₄S₇^2-, can be utilized to serve as ligands for in-situ-synthesized water-based PbS quantum dots (QDs), achieving a homogeneous and stable aqueous QDs solution without needing further conventional secondary ligand exchange. Our study provides a general strategy for the synthesis of various MCCs using water as safer and more environmentally friendly solvent alternative to hydrazine, thus greatly enhancing the wide applications of MCCs in solution-processed inorganic semiconductors.

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