A p-n junction composed ofAg+-doped manganite La0.8Ag0.2MnO3 (LAMO) and Nb-0.5wt％-doped SrTiO3 (STON) was fabricated using the pulsed laser deposition method.The heterojunction exhibits a good rectifying property over a wide temperature range from 20 to 390K.The minimum diffusion potential and the lowest leakage currents under different negative voltages both occur at 320 K,which is around the metallic-insulator transition temperature of the LAMO film.The photovoltage rises with the decreasing temperature and wavelength of the laser beam.Under the illumination of a 473nm laser beam,the photovoltage grows as the light power increases and seems to be saturated at about 300mW.The maximum VOC is 0.76 V,which is close to the diffusion voltage.