A facile hot-pressing process for fabricating flexible top electrodes of piezoelectric ZnO nanowire nanogenerators

We report a facile and effective hot-pressing strategy for fabricating the flexible top electrode for a piezoelectric nanogenerator (PENG). Flexible stainless steel (SUS) foil was employed as the bottom electrode and substrate of the device. Zinc oxide nanowires (ZnO NWs) were grown on SUS substrate through the hydrothermal synthesis method. The top electrode of Zn foil was combined with dielectric polydimethylsiloxane (PDMS) film using the hot-pressing process. The resulting top electrode is thick enough to enable the device to generate piezoelectric output differently under bending conditions. The PENG devices generated an output voltage of about 2.2 V and an output current of 8 nA under the optimum operating conditions. The devices fabricated by the hot-pressing process were robust enough to retain their generating ability after thousands of bending and releasing cycles.