Oxygen vacancy mediated temperature dependent emission behavior of localized bound excitons in ZnO nanorods

The present work reports on the tunable optical emission from oxygen vacancies in ZnO nanorods. The common green luminescence at room temperature originated from oxygen vacancy defects can be mediated by simply controlling pH values of alkaline solutions without the introduction of any intentional dopants. The peak energies of the green band are found to be monotonously tuned in the range from 2.17 to 2.47 eV, which could promote the applications of tunable wavelength ZnO optoelectronic devices. The temperature dependent behavior of exciton transitions and oxygen vacancy recombinations in ZnO nanorods is investigated in detail. It is suggested that the localized bound exciton (LBX) attached near the lateral facets of ZnO nanorods could survive up to nearly room temperature due to the large binding energy.