Tutorial ES21—Nanogenerators and Piezotronics—Principles, Materials, Devices and Nanosystems

Nanogenerators and piezoelectric are the two recently developed technologies for effective harvesting of ambient mechanical energy for self-powered systems. Ever since the wide-range applications of laptop computers and cell phones, the search for power sources for driving portable electronics has become increasingly important. The current technology mainly relies on rechargeable batteries. However, for the near future, micro-/nanosystems will be widely used in health monitoring, infrastructure and environmental monitoring, Internet of Things and defense technologies. The traditional batteries may not meet or may not be the choice for power sources. The nanogenerator was invented to meet these technological challenges. There are currently three effects commonly used for converting tiny physical motion into electricity: piezoelectric, triboelectric and pyroelectric effect. Piezoelectricity, a phenomenon known for centuries, is an effect of the production of electrical potential in a substance as the pressure on it changes. Piezo-photonics has attracted much attention because it may find broad applications in mechano-optical conversion, structural health diagnosis, nondestructive analysis, novel light sources and displays. The piezo-phototronic effect is a result of three-way coupling among piezoelectricity, photonic excitation and semiconductor transport, which allows tuning and controlling of electro-optical processes by strain-induced piezopotential. The tutorial will include two sections:

• Nanogenerators–From Sustainable Power Source to Self-Powered Systems
• Piezotronics, Piezo-Photonics and Piezo-Phototronics–From Electrochemical Catalyst to 2D Materials

8:30 am—Nanogenerators and Piezotronics—History and Fundamental Principles
Zhong Lin Wang, Georgia Institute of Technology

Wang will first introduce the fundamental science, engineering approach and technological applications of nanogenerators as a sustainable, self-sufficient power source for micro-/nanosystems by harvesting energy from our body and living environment. He will then introduce the fundamentals of piezotronics and piezo-phototronics and give an update on the progress of their applications in energy science, electronics and sensors.

9:15 am—High Performance Triboelectric Nanogenerators for Continuous Self-Powered Electronics
Jeong Min Baik, Ulsan National Institute of Science and Technology

Baik will first introduce the fabrication of triboelectric nanogenerators with high-output as well as the preparation of the triboelectric active materials. This will be followed by a review of the physical and chemical understanding for the mechanism to generate the high output in terms of energy-conversion efficiency. Baik will also survey the potential applications for the self-powered systems such as IoT sensors, filters, etc.

10:00 am—BREAK

10:30 am—Triboelectric Nanogenerators for Internet of Things
Haixia Zhang, Peking University

This part will introduce the development of IoT and requirements of energy harvesting. Then, we will review the progress of materials, performance of triboelectric nanogenerators and other energy harvesters. Lastly, the demonstrations of TENGs for IoT Applications will be investigated with the latest research achievements. The trend of IoT, TENGs and energy harvester technology will be discussed.

11:15 am—Implantable and Wearable Self-Powered Medical Electronics
Zhou Li, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences

This part will begin with a demonstration of the first in vivo mechanical energy harvester and devices. We will then show a pacemaker prototype for controlling the frequency of a heartbeat for the first time. Finally, Li will demonstrate other applications such as real-time acquisition and wireless transmission of self-powered cardiac monitoring data. These works are concentrated on live-powered implantable medical devices.

1:30 pm—Piezotronic Effect for Efficient (Photo)Electrochemical and Catalyst Applications
Xudong Wang, University of Wisconsin–Madison

This part will first discuss the fundamental principles of applying the piezotronic effect in engineering the interfacial band structure. Practical systems that implement the piezotronic enhancement will also be discussed. Lastly, Wang will show that piezoelectric potential can raise the energy of electrons at the surface of piezoelectric material (or electrode) to such a level that is sufficient to drive proton reduction reactions within its immediate vicinity.

2:15 pm—Piezotronics for 2D Materials
Wenzhuo Wu, Purdue University

This part will first elaborate on the fundamental physics and materials science of the piezotronic effect in 2D materials, which serve as the basis for understanding and utilizing the interfacial and charge-carrier engineering in 2D piezotronics. Wu will then discuss the latest progress in the fundamental exploration and technological advances in 2D materials piezotronics. Finally, he will provide a perspective of this rapidly advancing field.

3:00 pm —BREAK

3:30 pm—Piezo-Phototronics of 3rd Generation Semiconductor
Weiguo Hu, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences

This part will first introduce the framework of the piezo-phototronic effects in III-Nitrides quantum well. Furthermore, Hu will survey the carrier dynamic process in piezo-phototronic effects with the transit piezo-phototronic model and time-resolved photoluminescence. Finally,  he will discuss the applications of the piezo-phototronic effect on III-Nitrides visible light communications, micro LEDs and solar cells.

4:15 pm—Principle and Luminescence Application of Piezo-Photonics
Jianhua Hao, The Hong Kong Polytechnic University

This part will first introduce physical mechanisms of piezo-photonics. Some host materials and metal-ion activators will be described for demonstrating the piezo-photonic effect. Hao will then provide a unified profile and recent prototypical demonstrations of light emission triggered by various mechanical stimuli. Finally, he will discuss the challenges and perspectives of this research field.