Researchers Design Hybrid Solar-Vibration Energy Harvester

Researchers from South Korea have devised a nanotechnology-inspired hybrid device that can harvest energy from both sunlight and sound vibrations simultaneously, paving the way for the creation of cells that can potentially create a continuous and reliable energy source by leveraging the versatility of their energy sources.

A team of researchers including Dae-Yeong Lee from Sungkyunkwan University and the Samsung Advanced Institute of Technology created the device by integrating a piezoelectric nanogenerator and a silicon nanopillar solar cell to successfully harvest energy from two sources, "demonstrating its strong potential as a future ubiquitous energy harvester," they wrote in a paper.

Scientists have already come up with a number of ways for devices to harvest energy from the sun, wind, sound vibrations, and even ambient electricity that hovers in the air from device and appliance emissions. But the new hybrid device like the one described in the paper would be able to overcome some of the limitations of one-source energy harvesters, which depend upon their environment to work effectively, researchers said.

"Solar cells and nanogenerators require specific environmental conditions, such as solar light and mechanical vibration," Lee and his team wrote in the paper. "Thus, there is an increasing demand for a hybrid system that utilizes two or more energy sources in order to harvest ubiquitous energy continuously."

Researchers developed the device by integrating a silicon nanopillar cell -- the sunlight-harvesting part of the device -- with a piezoelectric nanogenerator. They fabricated the silicon nanopillar cell using a mask-free plasma etching process, and used a spin coating method to stack the piezoelectric nanogenerator atop the solar cell, according to the paper.

Researchers tested the device and found it could generate solar electricity with a 3.29 percent conversion efficiency while simultaneously generating 0.8 volts from the piezoelectric nanogenerator. The nanogenerator's output was based on exposure to a sound of 100 decibels. This type of result proved the device demonstrated "its strong potential as a future ubiquitous energy harvester," researchers said.

In addition to successfully harvesting energy from each of its components simultaneously, the device is also extremely compact, with a height of several hundred nanometers. This means it can fit in some of the smallest devices designed for ultra-low power that are beginning to leverage different types of harvesters rather than use batteries for power.

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