Monolithic Perovskite Solar Capacitor Enabled by Double-Sided TiO2 Nanotube Arrays

An integrated power pack that renders simultaneous solarenergy harvesting and storage represents a particularly promising energysource toward future applications. Herein, we report a high-performancehybrid power pack of perovskite solar cell (PSC) and supercapacitor viacapitalizing on double-sided TiO2nanotube arrays that have a dual-functionas electron transport layer (ETL) for PSC and cathode for supercapacitor,respectively (i.e., a monolithic perovskite solar capacitor). Specifically, asimple yet robust acid-treatment strategy followed by selective oxygen plasmaexposure on only the PSC side is employed to concurrently increase theperformance of double-sided TiO2nanotube electrodes in both the PSC andsupercapacitor units. Intriguingly, the integrated power pack delivers fastresponse under photocharging because of efficient charge transfer across thetwo sides of the TiO2nanotube array electrode, attaining a high overalloptoelectrical energy conversion and storage efficiency of 9.18%. This work demonstrates a viable route to engineeringintimately linked energy conversion-storage systems of interest.