A scalable, flexible and transparent GaN based heterojunction piezoelectric nanogenerator for bending, air-flow and vibration energy harvesting. (15th July 2018)

• Record Type: Journal Article
• Authors: Johar, Muhammad Ali; Kang, Jin-Ho; Hassan, Mostafa Afifi; Ryu, Sang-Wan
• Is Part Of: Applied energy. Volume 222(2018)
• Page Start: 781
• Page End: 789
• Publication Date: 2018-07-15
• Subjects: Electrochemical lift-off -- Flexible piezoelectric nanogenerators -- Free carrier screening -- Junction screening; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2018.04.038
• Languages: English
• ISSNs: 0306-2619

Abstract

Graphical abstract: Highlights: A novel fabrication of GaN based heterojunction flexible piezoelectric generator. Piezoelectricity from vibrations, finger force, air-flow, and cyclic agitation. High electrical energy generation from ambient vibrations. High output voltages by suppressing internal screening and junction screening. Abstract: Flexible functional devices are extremely suitable for malleable, sustainable, and portable applications such as smart clothing, flexible electronics and medical applications. Here, we present a scalable, transparent, and flexible piezoelectric nanogenerator (STF PNG) fabricated by forming a p-n NiO/GaN heterojunction using an electrochemical lift-off process to transfer GaN onto a flexible substrate. Several actuation sources such as air-flow, finger forces for bending, vibrations with a frequency of 20 Hz, and cyclic stretching-releasing agitation by a linear motor were applied to generate piezoelectric bias. Peak piezoelectric output voltage and current of 30 V and 1.43 µA, respectively, were measured. Such high piezoelectric bias was generated by suppressing free carrier screening and junction screening; the former was achieved due to removal of compressive stresses from GaN after the lift-off process, while the latter was achieved by the deposition of a highly resistive p-type NiO layer on transferred GaN and a sandwiched Polydimethylsiloxane resulting in a very high junction resistivity of the p-n NiO/GaN heterojunction STF PNG. As a result, our approach provides a new strategy for novel and highly efficient design of semiconductor-based flexible PNGs for a wide variety of applications.