Integration of SnO2-MXene photo-supercapacitor with perovskite solar cell in two-electrode configuration

Abstract

Integrated energy harvesting and storage devices are essential for powering next-generation, self-sustaining electronics. Here, we report a monolithic photo-supercapacitor (PS) that combines a perovskite solar cell (PSC) and a supercapacitor (SC) through a unified SnO₂-MXene nanocomposite, which simultaneously functions as the electron transport layer in the PSC and the active electrode in the SC. This multifunctional approach not only simplifies device architecture but also enhances charge extraction, conductivity, and energy storage performance. The optimized PSC achieved a power conversion efficiency of 14.16%, which improved to 16.11% after ambient aging, while the SnO₂-MXene SC electrode exhibited a specific capacitance of 214 F g⁻¹ at current density of 2 A g⁻¹. The integrated PS device demonstrated an areal capacitance of 77.4 mF cm⁻², an energy density of 6.85 µWh cm⁻², and a power density of 0.24 mW cm⁻², outperforming many state-of-the-art PSC-SC hybrids. This work establishes a new material strategy for compact, high-performance PS and offers a practical route toward wearable and IoT-oriented self-powered systems.