Fabrication of cobalt-doped lead sulfide nanoparticles sensitized solar cell

Abstract

Quantum dot solar cells (QDSCs) have gained considerable attention because of their tunable bandgap, high absorption efficiency, and potential for cost-effective energy conversion. This research focuses on the development and analysis of cobalt-doped lead sulfide (Co-doped PbS) quantum dots (QDs) placed on zinc oxide (ZnO) nanoflowers for application in QDSCs. Cobalt ions were incorporated into the PbS quantum dot lattice to modify optoelectronic properties and enhance power conversion efficiency. ZnO nanoflowers were synthesized via a hydrothermal process, while Co-doped PbS QDs were prepared using the successive ionic layer adsorption and reaction (SILAR) method. The structural and optical properties of the quantum dots were analyzed using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), and UV-Vis absorption spectroscopy, confirming successful cobalt doping and uniform quantum dot size distribution, with an average particle size of 5.9 nm. Photovoltaic performance was evaluated through current-voltage (J-V) measurements under simulated sunlight (AM 1.5G). The results demonstrated a significant increase in open-circuit voltage (Voc), short-circuit current density (Jsc), and power conversion efficiency (PCE) compared to undoped PbS QDSCs. The highest efficiency was achieved with Co-doped PbS QDs fabricated using 8 SILAR cycles, yielding a Voc of 0.12V, Jsc of 3.09 mA/cm2, and a PCE of 0.095%. However, contrary to theoretical expectations, the J-V curve only exhibits marginal improvements in Voc and Jsc, resulting in lower-than-anticipated overall efficiency. Further analysis indicates that cobalt doping may have introduced defects, contributing to moderate degradation and increased non-radiative recombination, adversely affecting device performance. Despite current challenges, this study underscores the potential of cobalt-doped PbS QDs for advancing low-cost, highly efficient QDSCs.