A highly-durable, highly-flexible transparent electrode (FTE) is developed by applying a composite made of a thin metal grid and a doped conducting polymer onto a colorless polyimide-coated NOA63 substrate. The proposed FTE exhibits a transparency of 90.7% at 550 nm including the substrate and a sheet resistance of 30.3 Ω/sq and can withstand both moderately high-temperature annealing (∼180 °C) and acidic solution (70 °C, pH 0.3) processes without performance degradation. The fabricated FTE yielded good mechanical stability under 10 000 cycles of bending deformations at a bending radius less than 1 mm without degradation of electrical conductivity. The high durability of the proposed FTE allows for the fabrication of flexible energy harvesting devices requiring harsh conditions, such as highly flexible perovskite solar cells (FPSCs) with a steady-state power conversion efficiency (PCE) of 12.7%. Notably, 93% of the original PCE is maintained after 2000 bending cycles at an extremely small bending radius of 1.5 mm. The FPSCs installed on curved surfaces of commercial devices drive them under various environments. The applicability of the proposed FTE is further confirmed via the fabrication of a flexible perovskite light-emitting diode. The proposed FTE demonstrates great potential for applications in the field of flexible optoelectronic devices.
Keywords: conducting polymer; highly flexible; light-emitting diode; metal grid; perovskite solar cell; transparent electrode.