Optical and Electrical Properties of Size-Controlled Cu–7,7',8,8'-Tetracyanoquinodimethane Nanocrystals

Abstract

We report the optical and electrical properties of Cu-TCNQ (TCNQ = 7,7 0 ,8,8 0 -tetracyanoquinodimethane) nanocrystals (NCs) fabricated by previously reported chemical reduction reprecipitation methods. The size of the resulting NCs ranges from 50 nm to 10 mm along the long axis. Raman experiment, X-ray photoelectron spectroscopic experiment, and elemental analysis reveal that these NCs have few TCNQ dianions due to the excess amount of Cu. The absorption of interband transition in the near-infrared region shows a blue shift, and the band gap increases with decreasing NC size. The obtained NCs show high electric conductivity, compared with typical Cu-TCNQ microcrystals, and multistep switching due to the existence of TCNQ dianions. #