Photovoltaic spectra for lead selenide diffusedp‐njunctions have been studied versus temperature and substrate impurity concentration. The shape of the spectra and its variation with these two parameters can be explained by taking into account the contribution to photovoltage of several mechanisms. At low photon energies, absorption near the junction is dominant. On the high‐energy side, the flat response can be assigned to absorption in the substrate material, followed by spontaneous reemission (radiative energy transfer). In the intermediate region, the dip in photoresponse is due to variations in the spatial distribution of photoexcited carriers which are generated in a wide region of chemical impurity gradient. Careful evaluation of those parameters which we measured in ourp‐nstructures fits with the characteristics of PbSe studied by other methods.