Emerging Devices Based on Two-Dimensional Monolayer Materials for Energy Harvesting

Two-dimensional(2-D)materials of atomic thickness have attracted considerable interest due to their excellent electrical,optoelectronic,mechanical,and thermal properties,which make them attractive for electronic devices,sensors,and energy systems.Scavenging the otherwise wasted energy from the ambient environment into electrical power holds promise to address the emerging energy needs,in particular for the portable and wearable devices.The versatile properties of 2-D materials together with their atomically thin body create diverse possibilities for the conversion of ambient energy.The present review focuses on the recent key advances in emerging energy-harvesting devices based on monolayer 2-D materials through various mechanisms such as photovoltaic,thermoelectric,piezoelectric,triboelectric,and hydrovoltaic devices,as well as progress for harvesting the osmotic pressure and Wi-Fi wireless energy.The representative achievements regarding the monolayer heterostructures and hybrid devices are also discussed.Finally,we provide a discussion of the challenges and opportunities for 2-D monolayer material-based energy-harvesting devices in the development of self-powered electronics and wearable technologies.