Influence of ammonium iodide precursor on the structures and lifetime of charge carriers in the lead sulfide photosensitive elements

The structure and characteristics of photosensitive elements based on thin films of lead sulfide (PbS) were studied. The films were prepared by chemical precipitation in the presence of a precursor (ammonium iodide (NH$_4$I)) in different molar concentrations. It has been established that iodine and its compounds (formed at an early stage of thin film deposition) lead to a change in the formation mechanism of the material structure. In turn, this leads to a decrease in the thickness of the oxygen-containing layers between the crystallites and has a decisive influence on the increase in the mobility of charge carriers. It is shown that the increase in photosensitivity at low frequencies (up to 800 Hz) is associated with the formation of oxygen-containing compositions and the appearance of a second group of charge carriers with lifetimes of 860–930 $\mu$s.