A novel hierarchical solution-processed fractional structured molybdenum oxide (MoO3) catalyst is fabricated from tricarbonyltris (propionitrile) molybdenum and used as the counter electrode of all-solid-state fiber-shaped dye-sensitized solar cells (S-FDSSC). The Tafel plot results and electrical impedance spectroscopy suggest that the use of the fractional structured MoO3 catalyst enhances the efficiency of the reduction of I-3 to 3I at the counter electrode/electrolyte interface. Because of the improvements of the short-current circuit and fill factor, the power conversion efficiency of the MoO3-modified S-FDSSC improves by 60% compared with that of the reference S-FDSSC. In addition, because of the robust fractional structure of MoO3, the MoO3-modified S-FDSSC maintains 90% and 95% of efficiency after 350-fold bending and the incident light angle dependency test, respectively. At 65% humidity and at 65 degrees C, the power conversion efficiency of the MoO3-modified device decreases by <20% after 350 h of storage, while that of the reference device drops by more than 70%. (C) 2020 Elsevier Inc. All rights reserved.