Pure UV emitting ZnO nanosol were prepared by sol-gel method using steric cleaner. Their band gap was approximately 6 eV. Hence the increase in band gap compared to bulk ZnO (3.37 eV) is attributed to decrease in particle size to nano-order and quantum confinement effect. Absorbance and photoluminescence property of the ZnO sols were investigated. Novel property of the prepared ZnO nanosol is that they showed no absorption, emission and excitation in the visible region, but only in the UV

more »

... . Maximum UV emission was around 340 nm and 320 nm for excitation at 227 nm and 250 nm, respectively. The UV emission is due to excitonic emission and the absence of visible emission is due to absence of intrinsic defects. Such ZnO nanoparticles with pure UV emission and no visible emission is rare, but is on demand, hence it adds advantage to the experimental method. Additionally, the emission spectrum of the ZnO sols showed size dependent stokes shift of around 2.3 eV compared to their absorption spectrum, which is due to decrease in particle size to nano-order and the vibrational relaxation of the excited nanoparticles to the ground state. The ZnO nanosol due to its wide band gap can be used in engineering high voltage and high temperature electronic applications.