(002)-Preferred orientation ZnO and Li-doped ZnO thin films on glass substrates and Li-doped ZnO/ZnO bilayers on fluorine-doped SnO2 glass substrates are grown by pulsed laser deposition technique. These films are characterized by X-ray diffraction, UV-visible transmission spectroscopy, surface photovoltage spectroscopy, and electric measurements. The optical transmittance of Li-doped ZnO/ZnO bilayers is about 86%. The bilayer grown on FTO glass substrates exhibits a typical rectifying characteristic of p-n heterojunctions. In addition, the photovoltaic response of ZnO is blue-shifted from 380 to 363 nm and greatly enhanced resulting from the formation of p-n homojunctions based on ZnO. (C) 2013 Elsevier B.V. All rights reserved.