Optical properties and carrier dynamics in Co-doped ZnO nanorods

TL;DR

This study investigates how Co doping modifies the optical and electronic properties of ZnO nanorods, showing enhanced visible light absorption and improved photoelectric efficiency, with surface defects playing a key role.

Contribution

It provides new insights into how transition metal doping, specifically cobalt, can be used to tune the optoelectronic properties of ZnO nanorods for potential applications.

Findings

Co doping extends light absorption into visible spectrum

Surface defects influence electronic behavior significantly

1% Co doping improves IPCE of ZnO nanorods

Abstract

The controlled modification of the electronic properties of ZnO nanorods via transition metal doping is reported. A series of ZnO nanorods were synthesized by chemical bath growth with varying Co content from 0 to 20 atomic % in the growth solution. Optoelectronic behavior was probed using cathodoluminescence, time-resolved luminescence, transient absorbance spectroscopy, and the incident photon-to-current conversion efficiency (IPCE). Analysis indicates the crucial role of surface defects in determining the electronic behavior. Significantly, Co-doping extends the light absorption of the nanorods into the visible region, increases the surface defects, shortens the non-radiative lifetimes, while leaving the radiative lifetime constant. Furthermore, for 1 atomic % Co-doping the IPCE of the ZnO nanorods is enhanced. These results demonstrate that doping can controllably tune the functional electronic properties of ZnO nanorods for applications.