Aqueous synthesis of CdSeTe-alloyed quantum dots, fabrication of CdSeTe, CdS and CdSe QDs-sensitized solar cells and optimization of the sensitizing, light scattering and passivating layers

In this research, quantum dot-sensitized solar cells (QDSCs) with multilayer photoelectrodes, i.e., the TiO nanocrystals/CdSeTe/CdS/CdSe/ZnS, were fabricated and investigated. The CdSeTe nanocrystals (NCs) were easily synthesized in aqueous solution and deposited on nanocrystalline TiO scaffold through drop-casting method. The other sensitizing/passivizing films were also prepared by successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) methods. It was shown that QDSC with TiO nanocrystals/CdSeTe/CdS/ZnS photoanode demonstrated an energy conversion efficiency of 2.95%. This efficiency was enhanced about 30% through the addition and optimization of a CdSe QDs film in the photoelectrode. The CdSe-sensitizing film was effectively deposited in just 9 min and ZnS was applied as the normal passivating film. In the next stage, TiO hollow spheres (HSs) were prepared with desired dimension via a template scarifying approach to enhance the light travelling path inside the photoelectrode and increase the light harvesting efficiency. The mentioned point resulted in 12% enhancement compared to the HSs-free QDSC. The last improvement was finally performed by optimization of the ZnS passivating layer and showed a 30% improvement in PCE of the final QDSC in comparison with HSs-free CdSeTe/CdS/CdSe-sensitized solar cell. The pioneer cell was compared with the CdSe and HSs-free reference cell which demonstrated a considerable 68% enhancement in photovoltaic performance.