Flexible Nanocarbon Electrodes for Holistically Engineered Solar Cell and Battery Integrated Piezoresistive Sensor

Herein, a sustainable graphitic carbon derived from waste polystyrene plastics (PS‐G) has been developed and a proof of concept for the integration of organic solar cells, Al‐ion batteries, and piezoresistive sensors based on PS‐G electrodes has been provided. First, a flexible organic solar cell (OSC) with the PS‐G interfacial layer between the photoactive material and the Al metal has enhanced charge extraction mobility with a power conversion efficiency (PCE) of 3.5%. A new range of possibilities in metal:semiconductor:carbon:metal contact and interfacial tuning in OSCs are made possible by the fact that pure PS‐G without Al can successfully extract electrons with a PCE of 0.89%. Second, when used as the cathode in an Al–carbon battery, PS‐G demonstrates a specific capacity of 148 mAh g −1 at 50 mA g −1 . At different current densities, PS‐G cathodes demonstrate high cycling stability (with 65% capacity retention over 100 cycles). Finally, the best of the fabricated OSCs and the Al–carbon batteries are then combined with a piezoresistive sensor that includes an active PS‐G electrode. The battery‐powered sensor has a resistance of 40–45 × 104 Ω while the solar‐powered sensor has a resistance of 32–35 × 104 Ω, when subjected to mechanical stimuli, with a tensile strength of 20 N.