Comparison of UV optical properties of ZnO nanoparticles dispersed in traditional organic and novel bio-molecular solvents



Two types of ZnO nanoparticles were dispersed in a bio-molecular solvent and in ethanol. The mixtures were characterized by photoluminescence and absorbance measurements. Strong UV emission was observed near the band gap of ZnO at 380 nm. The parasitic green emission which normally appears in ZnO suspensions was weakened when ZnO was dispersed in the bio-molecular solvent. Suspensions were spin-cast on quartz, and then Al contacts were deposited by a standard lift-off process via e-beam lithography. Point contact current-voltage characteristics of the samples were measured under equal intensity conditions using 340 nm UV LED and white LED sources. The ratio of the UV photo-generated current to dark current was as high as 105. Finally, the photocurrent response spectrum was measured. The results show that ZnO nanoparticle is favourable for visible blind UV photodetectors. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)