Recently, the numerical simulation of solar cells has attracted tantamount scientific attention in the photovoltaic community because it saves on research time and resources before the actual fabrication of the devices in the laboratories. Despite significant advancements in the fabrication of quantum dot-sensitized solar cells (QDSSCs), the power conversion efficiency (PCE) is still low when compared to other solar cells such as perovskite. This efficiency gap poses a substantial challenge in harnessing the full potential of QDSSCs for widespread adoption in renewable energy applications. Enhancing the efficiency of QDSSCs is imperative for their commercial viability and widespread deployment. In this work, SCAPS-1D was used in the simulation of QDSSCs. The solar cell with a general configuration of FTO/TiO₂/PbS/HTL/Au was investigated. In the device, PbS quantum dots were inserted as the absorber layer, TiO₂ as the electron transport layer (ETL), gold as the back contact, and the following inorganic materials, i.e., copper (I) iodide (CuI), copper (I) oxide (Cu₂O), cadmium zinc telluride selenide (CZTSe), copper iron tin sulfide (CFTS), and copper zinc tin sulfide selenide (CZTSSe) were tested as HTL materials, and FTO acted as the conductive substrate. The best HTL material (CZTSSe) exhibited a PCE of 22.61%, with a fill factor (FF) of 84.67%, an open circuit voltage (V_oc) of 0.753 V, and a current density (J_sc) of 35.48 mA cm⁻². This study contributes to the field by employing SCAPS-1D simulations to optimize QDSSCs, exploring novel inorganic HTL materials for these solar cells and identifying CZTSSe as a promising low-cost HTL that significantly enhances both the performance and commercial viability of QDSSCs.

The increasing global demand for renewable energy has intensified the search for high-efficiency and cost-effective solar cell technologies. Quantum dot-sensitized solar cells (QDSSCs) have emerged as promising candidates due to their tunable optoelectronic properties and enhanced light absorption. In this study, SnS quantum dots were synthesized from dithiocarbamate complexes using different ligands, namely m-toluidine (SnS1), aniline (SnS2), and p-toluidine (SnS3), to investigate the influence of precursor chemistry on material properties and device performance. Structural analysis confirmed the formation of an orthorhombic phase for all samples, while morphological studies revealed well-dispersed nanocrystals for SnS1 (5.93 nm), increased aggregation for SnS2 (8.57 nm), and partially fused domains with an intermediate size for SnS3 (6.67 nm). Optical measurements showed bandgap energies of 2.8, 2.2, and 2.7 eV for SnS1, SnS2, and SnS3, respectively, with SnS3 exhibiting reduced charge-recombination behaviour. Photovoltaic devices fabricated using these materials yielded power conversion efficiencies of 3.40, 2.03, and 7.63% for SnS1, SnS2, and SnS3, respectively, with no significant improvement observed for bifacial configurations. The superior performance of SnS3 is attributed to an optimal balance between light absorption, morphology, and charge transport properties, highlighting the critical role of precursor ligand selection in tuning quantum dot characteristics for improved QDSSC performance.