Freestanding ZnO nanorod/graphene/ZnO nanorod epitaxial double heterostructure for improved piezoelectric nanogenerators. (March 2015)

• Record Type: Journal Article
• Authors: Shin, Dong-Myeong; Tsege, Ermias Libnedengel; Kang, Seok Hee; Seung, Wanchul; Kim, Sang-Woo; Kim, Hyung Kook; Hong, Suck Won; Hwang, Yoon-Hwae
• Is Part Of: Nano energy. Volume 12(2015:Mar.)
• Page Start: 268
• Page End: 277
• Publication Date: 2015-03
• Subjects: Double-sided heterostructures -- ZnO nanorods -- Preheating hydrothermal -- Graphene -- Nanogenerator; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2014.12.040
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: It has been intensively studied that vertically aligned ZnO nanorods over the last decade due to their remarkable piezoelectric properties and a potential for various applications. Here, we present a simple strategy for fabricating the freestanding ZnO nanorods/graphene/ZnO nanorods double sided heterostructures. The characterization of the double sided heterostructures by using SEM, and Raman scattering spectroscopy reveals the key process and working mechanism of a formation of the heterostructure. The mechanism is discussed in detail in term of the decomposed seed layer and the vacancy defect of graphene. The approach consists of a facile one-step fabrication process and could achieve ZnO coverage with a higher number density than that of the epitaxial single heterostructure. The resulting improvement in the number density of nanorods has a direct beneficial effect on the double side heterostructured nanogenerator performance. The total output voltage and current density are improved up to~2 times compared to those of a single heterostructure due to the coupling of the piezoelectric effects from both upward and downward grown nanorods. The facile one-step fabrication process suggests that double sided heterostructures would improve the performance of electrical and optoelectrical device, such as touch pad, pressure sensor, biosensor and dye-sensitized solar cells. Graphical abstract: Highlights: Freestanding epitaxial double heterostructures grown using a regulated preheating hydrothermal method are presented. The approach consists of a facile one-step fabrication process and could achieve ZnO coverage with a higher number density than that of the epitaxial single heterostructure. This improvement in the number density leads to a piezoelectric nanogenerator with an increased output voltage and current density.