Asian Basic and Applied Research Journal

Dye-sensitised solar cells (DSSCs) have attracted considerable attention as next-generation photovoltaic devices owing to their low fabrication cost, simple processing, and potential for achieving high efficiencies. Lead sulfide (PbS) quantum dots (QDs) were prepared and incorporated into dye-sensitised solar cells (DSSCs) employing natural Hibiscus sabdariffa dye as the primary sensitiser. The optical properties of the fabricated devices were analysed using UV–Vis spectroscopy, which revealed significant enhancement in absorption across the ultraviolet, visible, and near-infrared regions, confirming that PbS QDs effectively broadened the spectral response and improved the light-harvesting capability of the system. Photovoltaic performance was  evaluated through current–voltage (I–V) characterisation under simulated solar illumination at 100 mW/cm². The DSSCs containing a 0.05 M concentration of PbS QDs exhibited notable improvements in device parameters, achieving a short-circuit current density (Jsc) of 5.3 mA cm⁻², an open-circuit voltage (Voc) of 0.680 V, a fill factor (FF) of 0.557, and an overall energy conversion efficiency (η) of 2.01 %. These values were substantially higher than those of control DSSCs fabricated without PbS QDs, highlighting the beneficial role of QDs in enhancing the photovoltaic response. The observed performance improvement can be attributed to the unique optoelectronic properties of PbS, including their tunable bandgap and high charge transport characteristics, which facilitated more effective electron injection into the TiO₂ conduction band and minimised electron–hole recombination losses. In addition, favourable energy level alignment between PbS QDs and TiO₂ contributed to improved charge separation and transport dynamics, thereby increasing both photocurrent and photovoltage outputs. Overall, the study demonstrates that the integration of PbS QDs with natural dyes in DSSCs represents a cost-effective and sustainable strategy to enhance solar energy conversion. These findings provide insight into the potential of quantum dot–dye hybrid systems for next-generation photovoltaics, opening pathways for the development of high-performance and environmentally friendly solar energy devices.