Efficient passivation of SnO2 nano crystallites by Indoline D-149 via dual chelation

For the first time in SnO2 based dye solar cells, here we report, efficiency exceeding 3% of the cells consisting with Indoline D-149 dye with unmodified SnO2 nano-crystallites. The cells sensitized with metal free D-149 dye together with liquid electrolyte comprising with 0.5 M tetrapropyl ammonium iodide and 0.05 M iodine in a mixture of acetonitrile and ethylene carbonate (1:4 by volume) delivered a short circuit current density of 10.4 mA cm−2 with an open circuit voltage of 530 mV under the illumination of 100 mW cm−2 (AM1.5) having an efficiency of 3.1%. As evident from the FTIR measurement, strong surface passivation of recombination centers of SnO2 crystallites due to the dual mode of attachment of dye molecules to the surface of SnO2 via both COOH and S–O direct bond might be the possible reason for this enhancement in these SnO2 based cells.