Failure Mechanism for Flexible Dye-sensitized Solar Cells Under Repeated Bending

In this study, vacuum cold spraying method was used to prepare TiO₂ nano-porous coatings on ITO-PEN plastic substrate to assemble flexible dye-sensitized solar cells (DSCs). The performance evolution of the flexible DSCs during multiple bending was studied, and the bending failure mechanism were clarified. Results showed that there was a critical bending radius R_C (12 mm for outward bending mode, 9 mm for inward bending mode and 12 mm for alternating bending mode) while bending the flexible DSCs. When the bending radius was R_C, the efficiency of the flexible DSCs kept unchanged with increasing bending cycle. When the bending radius was lower than R_C, the efficiency of the flexible DSCs decreased with increasing the bending cycle. The performance degradation of the flexible DSCs was mainly dominated by the delamination and spallation of the TiO₂ coatings. Based on these results, the bending failure mechanism was proposed.