Photoluminescence properties of a single tapered CuO nanowire

Photoluminescence spectroscopy has been employed in order to explore the optical emission properties of a single CuO nanowire, grown on a copper grid in static air by simple thermal oxidation method. As the diameter of the single tapered CuO nanowire decreases, the green emission of the nanowire gradually shifts towards the higher energy side. A steady blue shift of 20 nm of the photoluminescence (PL) peak has been attributed to nanosize effect. Higher surface to volume ratio and enhanced surface defects along the growth direction of the nanowire might be responsible for the observed PL behavior. In addition, crystallization process along the length of the nanowire during growth to form pure CuO structure from the precursor state may also have some role in observed shift in the PL peak.