Colloidal Bismuth Chalcohalide Nanocrystals

Here we present a colloidal approach to synthesize bismuth chalcohalide nanocrystals (BiEX NCs, in which E=S, Se and X=Cl, Br, I). Our method yields orthorhombic elongated BiEX NCs, with BiSCl crystallizing in a previously unknown polymorph. The BiEX NCs display a composition-dependent band gap spanning the visible spectral range and absorption coefficients exceeding 10(5) cm(-1). The BiEX NCs show chemical stability at standard laboratory conditions and form colloidal inks in different solvents. These features enable the solution processing of the NCs into robust solid films yielding stable photoelectrochemical current densities under solar-simulated irradiation. Overall, our versatile synthetic protocol may prove valuable in accessing colloidal metal chalcohalide nanomaterials at large and contributes to establish metal chalcohalides as a promising complement to metal chalcogenides and halides for applied nanotechnology.

Automated summary

In this study, a colloidal approach was developed to synthesize bismuth chalcohalide nanocrystals (BiEX NCs) with adjustable band gaps. The obtained BiEX NCs exhibited chemical stability and solution processability, making them promising candidates for photoelectrochemical applications. The versatile synthetic protocol presented in this study could be valuable for the fabrication of colloidal metal chalcohalide nanomaterials.