Size dependence of optical properties in solution-grown Pb1 xFexS nanoparticle films

The optical band gap ( E g ) of Pb 1− x Fe x S solution-grown nanoparticle films was varied from 2.65 to 2.22 eV with an increase in iron concentration 0.25 ≤ x ≤ 0.75 in films grown at fixed pH and temperature by the chemical bath deposition method. The presence of excitonic structure in the ternary Pb 1− x Fe x S for x ≥ 0.50 suggests increasing binding energy with increase in iron concentration in the films. A shift of excitonic peak towards higher energy with an increase in iron concentration is also observed.