Origin of the Substrate-Dependent Stability of a High-Performance Perovskite Supercapacitor for Flexible Electronics

Thin-film-based energy storage devices, especially supercapacitors, are in high demand due to their high power density and ease of integration with portable electronic devices. However, their stability as well as performance is limited due to their substrate properties. Here we have fabricated halide perovskite-based flexible asymmetric supercapacitors by introducing quasi-solid-state gel electrolytes between two electrodes. We have studied the performance and stability of the supercapacitor fabricated on 50-and 200-μm-thick stainless-steel (SS) and 100-μm-thick flexible graphite substrates. A device fabricated on a thin SS substrate follows exponential decay-type behavior, while it is asymptotic for a flexible graphite substrate at a higher bending angle. Both devices are stable for a small twisting angle; however, the device performance decreases sharply for the SS substrate after 60° twisting angle due to fast delamination and crack formation. Bending and twisting cycle measurement of the supercapacitor on a flexible graphite substrate shows better cyclic stability over 50-μm-thick SS substrates due to dissipation of microstrain. To improve the operating voltage of the storage devices, stacked supercapacitors are designed with two or more subcells that can drive white light-emitting diodes (>3.0 V).