ZnO nanorods as a piezoelectric energy harvester from light induced flexions

Rapid growth is promoting the Internet of Things (IoT) to become one of the main branches of the semiconductor industry. Surprisingly, the IoT growth would have been even faster if economically attractive and reliable alternatives for batteries and wires had been available. Providing power supply to the IoT nodes is challenging regarding their: (i) quantity (close to 8x the human population), (ii) harsh operation environments, (iii) size (typical footprint much smaller than mm²) and (iv) hard-to-reach locations. Modern IoT node requires very small energy (less than 100μJ/cycle) to operate. Wire supply of energy is expensive and uncomfortable while using a battery requires periodic replacements/maintenance and produces tons of toxic waste. Energy Harvesting (EH) could be a solution to overcome the IoT supply difficulties offering self-supplied nodes enabling further IoT market growth. EH converts natural or waste energies (vibrations, heat losses, light, etc.) into useful energy. We present an innovative two-step conversion harvester capable of transforming light into electricity via the PieZoelectric (PZ) effect. Our approach uses a Photo- Mobile Polymer (PMP) integrated with the PZ material. PMP serves as light-to-movement transducer and PZ converts the light-induced PMP flexions into voltage. As a PZ material, a nanostructured ZnO nanorods were used as their fabrication is cheap and ready-to-use at industrial scale. ZnO performance characterization in a dedicated flexions simulator revealed energy as high as 80nJ during 55sec bending runs. This result encourages further PMP and ZnO optimization enabling extension of piezoelectrics onto light conversion.