Improved efficiency of CdS quantum dot sensitized solar cell with an organic redox couple and a polymer counter electrode

• The organic AT-/BAT and T-/T2 redox couples were used in CdS QDSSCs.
• The AT-/BAT and PEDOT are better than polysulfide electrolyte and Pt and CoS CEs.
• An improved η of 1.53% was obtained with the AT-/BAT electrolyte and the PEDOT CE.
• PEDOT CE deposited at high deposition charge has better electrochemical activity.
• The AT-/BAT outperformed T-/T2 electrolyte due to suppressed charge recombination.

Quantum dot sensitized solar cells (QDSSCs) based on an organic thiolate/disulfide redox couple (C7H5N4S-/C14H10N8S2 or C2H3N4S-/C4H6N8S2) and a polymer counter electrode [poly (3, 4-ethylenedioxythiophene), PEDOT] were fabricated and their photovoltaic performance were investigated. In CdS QDSSC, the organic C7H5N4S-/C14H10N8S2 electrolyte shows better performance than the polysulfide electrolyte, and the PEDOT counter electrode exhibits higher efficiency than that of the Pt counter electrode and the CoS counter electrode. An efficiency of 1.53% was achieved in this QDSSC. The influences of the morphology and the deposition charge of the PEDOT counter electrodes on the cell performance were also studied. Furthermore, it was found that the C7H5N4S-/C14H10N8S2 redox couple outperformed the C2H3N4S-/C4H6N8S2 redox couple due to reduced electron recombination.