(002)-Preferred orientation ZnO and Li-doped ZnO thin films on glass substrates and Li-doped ZnO/ZnO bilayers on fluorine-doped SnO 2 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 363nm and greatly enhanced resulting from the formation of p–n homojunctions based on ZnO.