Phosphorus-doped zinc oxide p–n homojunction thin film for flexible piezoelectric nanogenerators

• Published in: Nano energy 2015-11, Vol.18, p.126-132
• Main Authors: Kwon, Yang Hyeog, Kim, Doo-Hee, Kim, Han-Ki, Nah, Junghyo
• Format: Article
• Language: English
• Subjects: Flexible electronics; Piezoelectric nanogenerator; ZnO pn homojunction
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2015.10.009

The performance of zinc oxide (ZnO)-based piezoelectric nanogenerators (PENGs) has been largely limited by piezoelectric potential screening effect due to excess electrons in ZnO. To address this problem, we report here a method that can greatly enhance the performance of ZnO PENGs by reducing excess electrons. We formed ZnO p–n homojunction thin film, composed of unintentionally doped n-ZnO and phosphorus-doped p-ZnO, on the ITO/Ag/ITO(IAI) coated flexible substrate with a low sheet resistance of 3.03Ω/sq and a high optical transmittance of 88.16%, where were prepared by roll-to-roll sputtering. The fabricated PENG with a p–n homojunction demonstrates the output power up to ~140μW, which is approximately two orders of magnitude higher than that of the PENG only with ZnO. Besides, the output performance related with the p-ZnO and n-ZnO thickness ratio and the roles of p–n junction formation were also systematically investigated. The results here introduce a new method to further extend performance limit of ZnO-based PENGs. [Display omitted] •High performance piezoelectric nanogenerator was demonstrated by forming a ZnO p-n homojunction with phosphorus-doped p-ZnO the n-ZnO layers.•The p-n homojunction effectively reduces excess electrons in ZnO, leading to enhanced output power generation.•The ITO/Ag/ITO substrate provides good conductivity, transparency, flexibility, and reliability under periodically applied stress.