Persistent electrical energy generation from organic diodes under constant pressure: toward organic gravity nanogenerators

Here it is demonstrated that electricity can be continuously generated by pressing organic diodes with the poly(3-hexylthiophene) (P3HT) layers which are sandwiched between indium-tin oxide and aluminum (Al) electrodes. The optimized single devices with the 150-nm-thick P3HT layers are able to generate 60 μV and 45 μA by pressing, while persistent voltage (50 μV) and current (45 μA) generations are achieved by continuous pressing for 7 days. The charge generation by pressing of organic diodes is supported by the current density-voltage and capacitance measurements, while the friction of pi-orbital electrons in the P3HT chains upon pressing is proposed for the mechanism of persistent electricity generation. Organic diode modules with 14 sub-cells in series deliver ca. 0.4 V and ca. 20 μW. The present technology is expected to pave the way for next-generation energy conversion devices, organic gravity nanogenerators that enable continuous electricity generation by gravitational forces.