Hybrid cells for simultaneously harvesting multi-type energies for self-powered micro/nanosystems

Our living environment has an abundance of energies in the forms of light, thermal, mechanical (such as vibration, sonic wave, wind, and hydraulic), magnetic, chemical, and biological. Harvesting these types of energies is of critical importance for long-term energy needs and sustainable development of the world. Over the years, rationally designed materials and technologies have been developed for converting solar and mechanical energies into electricity. Photovoltaic relies on approaches such as inorganic pn junctions, organic thin films, and organic-inorganic heterojunctions. Mechanical energy generators have been designed based on principles of electromagnetic induction and piezoelectric effect. Innovative approaches have to be developed for conjunctional harvesting of multiple types of energies using an integrated structure/material so that the energy resources can be effectively and complimentarily utilized whenever and wherever one or all of them are available. We give a review on the hybrid cells that are designed for simultaneously harvesting solar and mechanical, and chemical and mechanical energies using nanotechnology. The two energy harvesting approaches can work simultaneously or individually, and they can be integrated in parallel and series for raising the output current and voltage, respectively. Innovative approaches have been demonstrated for developing integrated technologies for effectively scavenging available energies in our environment around the clock. (C) 2012 Elsevier Ltd. All rights reserved.