Influence of Morphology on the Optical Properties of Self-Grown Nanowire Arrays

Abstract

Nanostructured materials such as nanowire arrays often absorb light more strongly than thin films, so they can be used to improve the performance of solar cells. In this study, a series of self-grown Cu2S nanowire arrays with different diameters, lengths, and morphologies is prepared by solid–gas reaction between Cu foil and a mixture of H2S and O2. The structure of the arrays is characterized by XRD, TEM, XPS, and Raman. Their light absorption performance is investigated systematically by diffuse reflectance and photoluminescence spectroscopy. The nanowire arrays are single-crystal Cu2S semiconductors, and their band gap can be adjusted by changing the morphology, diameter, and length of nanowires in the arrays. The light-absorption ability is enhanced from 70% for a planar Cu2S film to 93.5% for a Cu2S nanowire arrays and is less sensitive to both the wavelength and incident angle of light because of the morphology and distribution of the nanowires. The light absorption is high (about 92–95%) over a wide range of wavelengths (240–670 nm) and only decreases by 3% as the incident angle increases from 10 to 40°. This research shows the potential of Cu2S nanowire arrays for use in solar energy applications.