<p>In this study, several strategies were employed to enhance the efficiency of quantum dot-sensitized solar cells. The MnS passivation layer, placed after the TiO₂ layer, effectively reduced the surface traps present in TiO₂, leading to an increase in efficiency. As a result, the efficiency increased from 2.45% for the CdS quantum dot-sensitized solar cell to 3% with the addition of the MnS layer. Also, the doping strategy in quantum dots led to the creation of intermediate states in the host material, which consequently reduced the band gap energy and improved light absorption. This resulted in a further increase in efficiency to 3.20% with the addition of 2% Mn doping. The use of a substrate containing TiO₂ hollow spheres allowed light to enter the substrate through multiple scattering and reflection, thereby increasing the optical path length and enhancing the current density. Finally, by adding a CdSe layer via CBD deposition onto the H1₂/HSs/MnS/CdS: Mn photoanode and examining the effect of deposition time on solar cell performance, the efficiency reached 5.01%.</p> Graphical Abstract <p></p>