Band gap engineering in PbS nanostructured thin films from near-infrared down to visible range by in situ Cd-doping

Effect of annealing on structural and optoelectronic properties of nanostructured ZnSe thin films

“…The band gap at annealing temperature 300 • C was found to be 2.67 eV, which is very close to that of bulk ZnSe (2.70 eV) [24]. The increase in energy band gap from 2.60 to 2.67 eV may be related with the existence of high-density levels within the band gap [25] and the structural changes causing quantum confinement effects in the ZnSe films with annealing temperature [21][22][23]. The calculated values of band gap are in good agreement with that of the films deposited by vacuum evaporation (2.63-2.64 eV) [9], screen-printing (2.66 eV) [26] and two-source evaporation (2.68 eV) [27] methods.…”

“…The films annealed at 100 and 200 • C show less transmittance at shorter wavelengths, whereas film annealed at 300 • C revealed higher transmittance. The variation in absorption edge most probably due to the improvement in structural order, removal of residual stresses and quantum confinement effects [21][22][23]. The films showed blue shift with the increase of annealing temperature, which indicates that absorption edge shifting towards bulk ZnSe.…”

Effect of double substitutions of Cd and Cu on optical band gap and electrical properties of non-colloidal PbS thin films

“…There have been several studies on Cd-substituted PbS thin films [12,18]. Depending on the content of Cd content, different crystal structure and optical properties were reported since CdS has a hexagonal wurzite structure compared to the cubic structure of PbS [12]. Cu is considered as a promising doping element because d-orbitals of Cu provide deep acceptor states in metal sulfides [19].…”

Properties of PbS: Ni2+ Nanocrystals in Thin Films by Chemical Bath Deposition

“…5 eV required for achieving a most efficient solar cell [8], likewise sizedependent new physical aspects have generated an ongoing thrust for new practical applications, and PbS nanocrystals with grain-size (GS) dimensions in the range 1-20 nm are of technological interest for advanced optoelectronic applications, showing a stronger quantum confinement effect when the crystallite size matches the dimension of Bohr exciton [9]. In this context, there are two situations called the weak confinement and the strong regimes [10]. In the weak regime the particle radius of the electron-hole pair, but the range of motion of the exciton, is limited, which causes a blue shift in the absorption spectrum.…”