Tuning the physical properties of PbS thin films towards optoelectronic applications through Ni doping

Ni-doped PbS (PbS:Ni) thin films were deposited on glass substrates by cost-effective spray pyrolysis technique with different concentrations of Ni (0, 2, 4, 6 and 8 at.%). XRD studies reveal that all the films exhibit face centered cubic structure. The preferential orientation of the undoped PbS film is along the (2 0 0) plane and for the doped films the preferential orientation is along the (1 1 1) plane. Optical studies show that the film transparency increases with increase in Ni doping concentration and the optical band gap exhibit a red shift from 2.26 eV to 2.06 eV. Electrical studies show that all the as deposited PbS:Ni thin films have resistivity in the order of 10−1 Ω-cm. Raman studies reveal that the peak at 161 cm−1 might have been originated from the combination of longitudinal and transverse acoustic phonon modes in PbS crystals. Increased transparency and nominal resistivity values obtained make PbS:Ni thin films suitable for optoelectronic applications especially in solar cells.