Efficiency improvement of CdS and CdSe quantum dot-sensitized solar cells by TiO2 surface treatment

CdS and CdSe quantum dots (QDs) have been synthesized via successive ionic layer adsorption and reaction for the fabrication of quantum dot-sensitized solar cells (QDSSCs). In this work, several approaches such as incorporation of ZnS passivation layer, scattering layer, treatment with TiCl4, and increasing the TiO2 layer thickness have been applied on TiO2 layer in order to improve the solar cell performance. By passivating the QD-sensitized TiO2 layer with ZnS, the performance of the cells increased due to reduction of charge recombination at the photoanode/electrolyte interface. With a thicker TiO2 layer thickness of 26 μm, further enhancement was observed. The efficiency of the CdS and CdSe QDSSCs improved from 1.06% to 1.48% and from 1.41% to 3.05%, respectively. On the other hand, scattering layer and treatment with TiCl4 did not bring much improvement to the cells.