Effects of calcination treatment on the morphology, crystallinity, and photoelectric properties of all-solid-state dye-sensitized solar cells assembled by TiO2 nanorod arrays

Abstract

TiO₂ has been extensively investigated due to its unique photoelectric properties. In this study, oriented single-crystal rutile TiO₂ nanorod arrays were synthesized and then calcined at different temperatures in the atmosphere. The morphology and crystalline characterization indicated that the length of TiO₂ nanorods increased rapidly and the nanorods became aggregated and fragile after calcination, yet the sintering treatment seemed to have almost no effect on the crystallinity. To obtain the all-solid-state, dye-sensitized solar cells (DSSCs), a newly reported solid inorganic semiconductor, CsSnI_2.95F_0.05, was employed as the electrolyte, and the Pt deposited on the conductive side of the fluorine-doped tin oxide (FTO) glass substrate was used as the counter-electrode. The effects of the calcination treatment on the photoelectric properties of the solar cells, including external quantum efficiency (EQE), open circuit voltage (V_OC), short-circuit current (J_SC), and photoelectric conversion efficiency (η), were investigated under the illumination of a solar simulator. As a result, all of the EQE, V_OC, J_SC, and η values of the cells first increased and then declined with the increase of calcination temperatures, and the highest η of 2.81% was obtained by the cell assembled with its TiO₂ electrode sintered at 450 °C for 3 h, a value almost 2.5 times that of the non-sintered sample (1.1%).