Improved performance of quasi-solid-state dye-sensitized solar cells based on iodine-doped TiO2 spheres photoanodes

We report on the synthesis of Iodine-doped hierarchical TiO2 spheres by a general hydrothermal method, and their application as photoanodes of quasi-solid-state dye-sensitized solar cells (DSSCs). The Iodine-doped TiO2 spheres were characterized by SEM, XRD, and XPS. The performance of I-doped TiO2 spheres based DSSCs was obviously enhanced, an optimized energy conversion efficiency of 6.38% was obtained, which increased by 34% compared with the cell based on undoped TiO2 (4.76%). The Iodine-doped and undoped TiO2 spheres based solar cell were analyzed by electrochemical impedance spectroscopy (EIS), intensity modulated photocurrent spectroscopy (IMPS), intensity modulated photovoltage spectroscopy (IMVS) and incident photon-to-current efficiency (IPCE) measurements. The results revealed that the enhanced performance could be explained by the expanded visible-light response, the reduced electron recombination, the improved electron transport and the prolonged electron life time in the TiO2 film by iodine doping. (C) 2018 Elsevier B.V. All rights reserved.