Synthesis, characterization and optical properties of Co2+ doped PbS nanocrystals

We present theoretical and experimental results in PbS nanocrystalline thin films systematically doped with Co2+ ions utilizing the green Chemical Bath Deposition technique at similar to 90 degrees C. All growth parameters are kept constant by systematically adding different solution's volume containing the Co2+ ions. We apply the first-order chemical kinetic reaction model to investigate some physicochemical parameters. The crystalline phase is investigated by X-ray Diffraction, identifying the cubic phase in all samples. After dopping the PbS sample (PbSCo2+), the grain size decreases from similar to 29.7 nm to similar to 15.7 nm and dislocation density increases from similar to 3.4 lines m(-2) to similar to 6.4 lines m(-2). The absorbance and bandgap studies conducted in the Vis-UV region show the typical S-1(e)-> S-1(h) and S-1(e)-> P-1(h) electronic transitions and the excitonic bands located at similar to 1.5 eV and similar to 1.8 eV due to higher energy transitions from D-1(h)-> D-1(e), and F-1(h)-> F-1(e) respectively in nanocrystals. Finally, we apply three theoretical models to elucidate the correlation associated with the crystal radius and the bandgap energy (E-g).