Hybrid printed three-dimensionally integrated micro-supercapacitors for compact on-chip application

The emerging internet of things requires autonomous and ubiquitous on-chip devices with wireless interconnectivity. On-chip power is required to meet the miniaturization requirement, and an integrated on-chip micro-supercapacitor has enormous potential to meet this requirement owing to its high-power density and long cycle life. However, the two-dimensional expansion of the current co-planer design paradigm of micro-supercapacitors, such as the interdigital layout, hinders the on-chip integration density, resulting in a significant consumption of precious chip footprint and an insufficient energy density. This article reports on the use of a three-dimensional framework along with a hybrid printing strategy to fabricate devices entirely without any post-processing, and highly integrated three-dimensional micro-supercapacitors were printed as proof of concept. The micro-supercapacitors exhibit more than 25 times areal capacitance than the interdigital ones (76 mF/cm 2 vs 2.9 mF/cm 2 ) due to their three-dimensional feature. Moreover, it can provide new functions to achieve adjustable voltage and capacitance flexibility within one device's footprint area. This approach can also enable devices on different substrates. An ultraviolet sensor was integrated with and powered by the three-dimensional micro-supercapacitors on polyimide to demonstrate the compact on-chip application. The three-dimensional framework offers a general solution to the on-chip integration challenges of micro-supercapacitors. Moreover, it can be extended to new materials or even other electronics units, highlighting the promise of further miniaturized and powerful micro-electronics.