“…Neither the traditional silicon solar cells nor the emerging perovskite solar cells can be comparable with FOPV in applications requiring flexible properties. Polyethylene terephthalate (PET), which has the characteristics of light weight and bending resistance, is a widely used ideal flexible substrate in organic electronic devices, including organic field-effect transistors [ 3 , 4 , 5 ], organic light emitting diodes [ 6 , 7 ], and FOPVs [ 8 , 9 ]. The research on FOPV primarily focuses on developing new polymeric functional materials [ 10 , 11 ], electrodes [ 12 , 13 , 14 , 15 , 16 , 17 , 18 ], and substrates [ 19 , 20 , 21 , 22 ].…”