Hexagonal ABX nanocrystals: rod-shaped BaNbS and BaTaS; BaTiSe, BaZrSe, and other selenide derivatives for optoelectronic applications.

Chalcogenide perovskites have increasingly garnered attention in recent years for various optoelectronic applications. While distorted perovskites such as BaZrS are primarily being explored for photovoltaic applications, hexagonal ABS compounds such as BaTiS have been proposed for optical devices and thermoelectrics due to their intriguing properties arising from their quasi-1D structure, which imparts anisotropy in properties. However, other members of the hexagonal family remain largely unexplored, likely due to their harsh synthesis conditions. In this report, we synthesize nanocrystals of relatively unexplored members of the hexagonal ABX chalcogenides family, which also possess a similar rod-like morphology and could be useful for polarized photodetection applications. Specifically, we modified our previously reported sulfide perovskite nanoparticle synthesis route to produce BaNbS and BaTaS nanocrystals. Furthermore, we explored selenium and selenourea as precursors to synthesize selenide hexagonal nanocrystals such as BaTiSe and BaZrSe, as well as other selenide analogues like BaNbSe and BaTaSe. This marks the first report of nanocrystal synthesis for the BaMSe family, where M is an early transition metal.