Though the origin of deep-level emission in CuO is under debate, and little information is available on the CuO defect structure, the deep emissions are generally supposed to relate to defects in CuO nanomaterial. CuO is intrinsically a p-type semiconductor due to the existence of Cu vacancies. However, recent theoretical calculations indicate that although Cu vacancies are the most stable defects in CuO, they do not change the electronic structures of CuO. Otherwise, oxygen vacancies or OCu antisite defects are likely responsible for these emissions, while their formation energy is not much different from the formation energy of Cu vacancies [35]. The green emission is commonly assigned to the singly ionized oxygen vacancies; the yellow or red emission has been supposed to relate to the interstitial metal ion in the oxide. Therefore, the evolution of green and yellow bands in CuO is competitive. The blue shift behavior of the near band edge transition compared with that of the bulk CuO, in combination with the findings from UV-vis analysis, was generally attributed to the enhancement of the quantum confinement effect resulting from the decrease in the dimensional structure and the size of the nanoparticles. One can also evaluate the concentration of structural defects by comparing the photoluminescence intensity ratio of near-band edge emission to green deep-level emission. Some groups applied this kind of assignment. Vila et al.Observed luminescence bands centered at 1.33, 1.23, and 1.11 eV in CuO nanomaterial and suggested that the emission with the highest energy corresponds to near band edge transition in CuO, while oxygen vacancies and oxygen on copper antisite defects most probably introduce the two other emissions. If you are looking for high quality, high purity, and cost-effective copper oxide, or if you require the latest price, please email contact mis-asia.
