Photoconductivity, dark-conductivity and photoluminescence study of hydrothermally synthesized ZnO nanoparticles

In the present work, we report on the photoconductivity (PC), dark-conductivity and photoluminescence (PL) measurements of hydrothermally synthesized Zinc oxide (ZnO) nanoparticles (NPs) with particle size 20-50 nm. The photoconductivity is observed in ZnO nanoparticles due to photoexcitation in the visible range (400 nm-691 nm). The photo and dark conductivity of ZnO NPs have been measured using thick film of powder with out any binder. The photo and dark current behavior as a function of various parameters such as field response, rise and decay time response was studied. The photocurrent (I
_pc
) and dark-current (I
_dc
) follows power law with applied field, I
_pc
¿ V
^r
due to the defect related mechanism including both recombination centers and traps. The ZnO NPs is found to have deep trap of 0.72 eV. The photoluminescence spectra of synthesized ZnO nanoparticles exhibited different emission peaks at 396 nm, 416 nm, 445 nm, 481 nm and 524 nm.