Frequency stable dielectric constant with reduced dielectric loss of one-dimensional ZnO–ZnS heterostructures. Issue 37 (16th September 2021)

• Record Type: Journal Article
• Authors: Zafar, Amina; Younas, Muhammad; Fatima, Syeda Arooj; Qian, Lizhi; Liu, Yanguo; Sun, Hongyu; Shaheen, Rubina; Nisar, Amjad; Karim, Shafqat; Nadeem, Muhammad; Ahmad, Mashkoor
• Is Part Of: Nanoscale. Volume 13:Issue 37(2021)
• Page Start: 15711
• Page End: 15720
• Publication Date: 2021-09-16
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d1nr03136h
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : ZnO–ZnS heterostructure is developed which shows frequency stable dielectric response at ≥10 3 Hz due to coupling of the bare charges in the form of overlapping large polaron and Zn 2+ –VO dipoles present at ZnO–ZnS heterostructure interface. Abstract : The synthesis of one-dimensional heterostructures having high dielectric constant and low dielectric loss has remained a great challenge. Until now, the dielectric performance of ZnO–ZnS heterostructures was scarcely investigated. In this work, large-scale ZnO–ZnS heterostructures were synthesized by employing the chemical vapor deposition method. High resolution transmission electron microscopy (HRTEM) confirms the formation of heterostructures. X-ray photoelectron spectroscopy (XPS) shows that S atoms fill up the oxygen vacancy (VO ) in ZnO, leading to the suppression of charge carrier's movement from ZnO to ZnS; instead there is charge transfer from ZnS to ZnO. Conductivity mismatch between adjacent ZnO and ZnS materials leads to the accumulation of free charges at the interface of the heterostructure and can be considered as a capacitor-like structure. The electrical behaviors of the potential phases of ZnO, ZnS and the ZnO–ZnS heterostructure are well interpreted by a best fitted equivalent circuit model. Each heterostructure acts as a polarization node with a specific flip-flop frequency and all such nodes form continuous transmission of polarization, which jointly increase the dielectric energy-storage performance. The orientational polarization of the polarons and Zn 2+ –VO dipoles present at the heterostructure interface contributes to the frequency stable dielectric constant at ≥10 3 Hz. Our findings provide a systematic approach to tailor the electronic transport and dielectric properties at the interface of the heterostructure. We suggest that this approach can be extended for improving the energy harvesting, transformation and storage capabilities of the nanostructures for the development of high-performance energy-storage devices.