Solvothermal synthesis of hexagonal pyramidal and bifrustum shaped ZnO nanocrystals: natural betacyanin dye and organic Eosin Y dye sensitized DSSC efficiency, electron transport, recombination dynamics and solar photodegradation investigations

K. Subalakshmi, J. Senthilselvan, K. Ashok Kumar, S. Arun Kumar, A. Pandurangan

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

In this research work, a novel hexagonal pyramidal and bifrustum shaped multifaceted ZnO nanocrystals with high specific surface area has been synthesized for the first time, by one pot solvothermal method without employing structure modifying surfactant or capping agent. The XRD and HRTEM results confirmed that the ZnO nanocrystals are grown in hexagonal wurtzite phase with (101) orientation. Also for the first time, by using the HRTEM images of hexagonal bifrustum shaped ZnO nanocrystal, simple geometric calculation is proposed to estimate its mass specific surface area, surface-to-volume ratio and ZnO unit concentrations. DSSC devices were fabricated by sensitizing the hexagonal ZnO nanocrystals with natural betacyanin dye (extracted from Cactus fruit pulp and Malabar nightshade berry fruit) and organic dyes (Eosin Y and Methylene blue organic dyes). Natural betacyanin Cactus dye and organic Eosin Y dye sensitizations of the multifaceted ZnO nanocrystal resulted in a high power conversion efficiency of 0.845 and 0.92%, respectively. The results on redox behavior and interfacial charge transfer kinetics of the DSSCs are discussed by using cyclic voltammetry and electrochemical impedance spectroscopy. Visible solar light assisted photodegradation behavior of the natural and organic dyes were investigated by using the multifaceted ZnO nanocrystal as photocatalyst, and it is found that natural betacyanin Cactus dye has resulted in good photostability for about one week duration and the photodegradation mechanism is explained. We successfully demonstrated for the first time a high efficiency in natural betacyanin Cactus dye sensitized nanocrystalline ZnO based DSSC device with better photostability than the organic Eosin Y sensitized device.

Original languageEnglish
Pages (from-to)15565-15595
Number of pages31
JournalJournal of Materials Science: Materials in Electronics
Volume28
Issue number20
DOIs
StatePublished - 1 Oct 2017

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