CdS quantum dot sensitized solar cells prepared using Al3+ doping into TiO2 photoanodes

Some quantum dot-sensitized solar cells (QDSSCs) were fabricated by doping Al3+ ions into the TiO2 in order to improve their efficiency. Results indicated that the photovoltaic parameters of the optimized cell were boosted compared with those of the reference cell which was free of Al3+ QDs indicating improvements in efficiency, current density and open-circuit voltage, respectively. It was found that the η value was increased by doping 0.1–0.3% of Al3+ into TiO2 paste but adding more amounts (0.4 and 0.5%) decreased the cell efficiency. The highest efficiency was 2.08% by Al3+ doping into the TiO2 photoanode which was 45% higher than that of the reference cell (η=1.43% for the cell made only using TiO2/CdS/ZnS photoanode). The short circuit current was increased from 6.58 mA.cm–2 in Al3+ free cell to 11.49 mA.cm–2 in the 0.3% Al3+-doped cell. The open circuit voltage was enhanced from 0.529 V in Al-free cell to 0.579 V in the 0.3% Al3+-doped cell. Thus, addition of 0.3%wt Al3+ as a dopant was appropriate to attain suitable photocurrent efficiency for the QDSSCs because it could be used in a minimum amount to improve the electron transport, drop the recombination rate and increase the cell efficiency.

Keywords:

Quantum dot sensitized solar cells , Al3+ doping , Photocurrent , Photovoltaic performance , Photoluminescence spectra