ZnS shell-like CdS quantum dot-sensitized solar cell grown by SILAR approach; effect of electrolyte, counter electrode, and shell thickness

Quantum Dot (QD) sensitized solar cells due to their high potential have attracted tremendous attention to become a low cost and reliable substitute for the fossil fuels. This study reports fabrication and optimization of the CdS QDs sensitized cells connected to ZnO nanowires (NWs) which were grown by hydrothermal method. Optimization process was done using a set of experiments, which were designed to systematically extract the best values. ZnS shell-like CdS QDs were synthesized on the surface of ZnO NWs by successive ionic layer adsorption and reaction approach. The effect of the different components on the charge transfer was studied. The cell with ZnO NW/CdS(4C)/ZnS(3C) as the photosensitizer, CuS as the counter electrode and Na2S 0.6 M, S 0.2 M and KCl 0.4 M in methanol/water (7:3) as the electrolyte exhibited the best performance with the efficiency of 0.419%. Although increasing the dot thickness was supposed to improve the cell performance, defects occurred during the growth, due to large mismatch of core and the shell, decay the cell's efficiency.