Facile synthesis of novel antimony selenide nanocrystals with hierarchical architecture by physical vapor deposition technique

Stoichiometric antimony selenide (Sb₂Se₃) nanocrystals have been successfully engineered by a facile physical vapor deposition method, employing a single precursor of polycrystalline Sb₂Se₃ charge in a closed quartz ampoule under high vacuum without any foreign seed or extraneous chemical elements. This work underscores the efficacy of the vapor deposition process and provides synthetic strategies to scale down bulk Sb₂Se₃ into novel nanostructures. The morphological evolution of the tailored architecture was examined on micro and nano size scales by scanning electron microscopy and high-resolution transmission electron microscopy. The intrinsic mechanism governing the nanostructure formation is revealed as layer-by-layer growth, related to the unique layered structure of Sb₂Se₃. The optical properties of the grown crystals were probed by UV–vis–NIR and photoluminescence tools. The band-gap values of the microfibers, nanorods, nanooctahedra and nanospheres estimated from UV–vis–NIR analysis are found to be 1.25, 1.47, 1.51 and 1.75 eV, respectively. Powder X-ray diffraction, energy-dispersive analysis by X-rays, X-ray photoelectron spectroscopy, Raman spectroscopy and photoluminescence studies confirmed the quality, phase purity and homogeneity of the as-grown nanostructures. The adopted physical vapor deposition method is thus shown to be a simple and elegant route which resulted in the enhancement of the band gap for the Sb₂Se₃ samples compared with their counterparts grown by chemical methods. This approach has great potential for further applications in optoelectronics.