Investigation of charge transfer in nanostructured hybrid solar cell using Kelvin Probe Force Microscopy

In this paper, a novel type of nanostructured hybrid solar cell based on zinc oxide nanowires is proposed. The structure of the novel device is ITO/zinc oxide nanowire/poly(3-hexylthiophene-2,5-diyl) (P3HT): single walled carbon nanotube (SWCNT)/PEDOT:PSS/SWCNT. In order to clarify the charge transfer process in the proposed nanostructure, Kelvin Probe Force Microscopy (KPFM) is employed to study the surface potential distribution at the interfaces between nanowires and their adjacent layers. A clear picture of the band alignment and charge transfer is obtained by studying surface potential change in the dark and under illumination. The role of SWNT is elucidated to be hole transporter, while zinc oxide nanowire is proved to act as electron transporter.