Room temperature exciton formation and robust optical properties of CVD-grown ultrathin BiOSe crystals on arbitrary substrates.

The appealing success of non-van der Waals (non-VdW) two-dimensional (2D) bismuth oxyselenide (BiOSe) crystals in optoelectronics provides an exciting avenue to investigate their fundamental physical properties. To date, the majority of efforts have focused on understanding the properties of 2D BiOSe, usually grown on a mica substrate. However, a gap exists in realizing the origin of photoluminescence (PL) of new age non-VdW BiOSe at visible and near-infrared (NIR) wavelengths and the effect of growth substrates on the structure and optical properties.