Photocapacitors integrating Binder-Free MXene Microsupercapacitor and Carbon Perovskite Solar Cell for Indoor Applications

The development of the Internet of Things (IoT) ecosystem, which encompasses large networks of connected devices, requires continuous and reliable power supply. Photocapacitors (PCs), which combine a solar cell with a (super)capacitor in a single device, offer a sustainable and compelling solution, mitigating the effect of intermittency of solar energy, thanks to the presence of an energy storage element, and allowing ubiquitous portable optoelectronic devices, for both outdoor or indoor lighting environments. In this work, we report for the first time the integration of a binder-free exfoliated Ti ₃ C ₂ T _x MXene microsupercapacitor (MSC) with a carbon-based perovskite solar cell (C-PSC) on a single glass/indium tin oxide (ITO) substrate. One terminal was shared between the MSC and the solar cell, and two additional terminals were dedicated to each individual device. The C-PSC demonstrated an efficiency of 7.11% under 1 sun illumination and 22.6% efficiency under indoor light intensity of 1000 lx. On the other hand, all blade-coated, laser scribed MXene-based MSC, with interdigitated in-plane layout, demonstrated a capacitance of 16 mF/cm² at 0.08 mA/cm² current density, good capacitance retention and coulombic efficiency over 6,000 charge-discharge cycles. The integrated PC achieved an overall efficiency under 1 sun illumination of 8.5% measured in constant current mode and 3.8% measured at open circuit voltage. The device was characterized also under 1000 lx at open circuit voltage, delivering 8% overall efficiency, showing promise as a compact and reliable self-rechargeable power supply pack for portable IoT devices.