Design strategy of TiO2/AgInSe/CdS/CdSe/ZnS photoanode and optimization of CdSe nanoparticles layer for increasing the efficiency of quantum dot-sensitized solar cells

In this study, ternary AgInSe (AISe) quantum dots compound were synthesized using a novel chemical precipitation method followed by a controlled hydrothermal treatment. The as-prepared particles were deposited onto a mesoporous TiO2 substrate to be applied as the photoelectrode of quantum dot sensitized solar cells (QDSSCs). Two configurations of multilayer photoanodes i.e. the TiO2 NCs/AgInSe/CdS/ZnS and TiO2 NCs/AgInSe/CdS/CdSe/ZnS were fabricated and employed for higher photovoltaic performance. The co-sensitizing CdS and CdSe nanocrystals layers were synthesized and deposited through successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) techniques, respectively. The results revealed that the QDSSCs with TiO2 NCs/AgInSe/ZnS photoanode initially showed an efficiency of 0.45 %. Incorporating CdS NCs as a quasi-shell film increased the efficiency to 3.9 % in the optimized TiO2/AgInSe/CdS(3 cycle)/ZnS configuration. Adding CdSe nanocrystals over-layer did not improve the efficiency of corresponding cells due to the increased thickness and resistance. Instead, the TiO2/AgInSe/CdS(2 cycle)/CdSe(12 min)/ZnS photoanode resulted in the efficiency of 4.10 % with 34 % improvement. Using the sub-micron size TiO2 hollow spheres (HSs) as the light scattering layer created further light absorption and enhanced performance. It was shown that the photovoltaic parameters were increased to short circuit current density (Jsc) of 23.25 mA/cm2, open-circuit voltage (Voc) of 512 mV and overall efficiency equal to 4.55 % [Display omitted] •The QDSCs with AISe, CdS and CdSe light absorbing QDs layers were fabricated.•AgInSe2 quantum dots were synthesized via a novel aqueous synthesis approach.•The influence of CdSe QDs layer thickness on PEC of the AISe/CdS QDSCs was investigated.•TiO2 hollow spheres were prepared and utilized for higher light absorption.•A PCE of 4.55 % was achieved for the QDSCs with TiO2/HSs/AISe/CdS/CdSe/ZnS photoanode.