Colloidal CdS Quantum Dot Fibers Prepared by Electrospinning of Their Wet Gel for Quantum Nanowires

Dimensional control of quantum dot (QD) assembly patterns has been widely studied for optoelectronic applications. Nevertheless, the long-range ordered one-dimensional (1D) structure of QDs is still challenging. In this study, 1D fibrous assembly of CdS QDs several hundred micrometers in length was achieved by electrospinning a wet QD gel with viscoelastic properties. In the purification of crude CdS QDs synthesized by a typical hot injection method, acetone with a controlled small amount of water was used to precipitate the QDs. Redissolution of such purified CdS QDs into toluene uniquely formed a wet gel. Rheology measurements showed that the formed wet gel showed viscoelastic properties and quick recovery after mechanical deformation. The internal structure of the QD gel was investigated by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, revealing that the QDs were densely packed with a network structure in the gel. Nanofibers of the CdS QDs were formed by electrospinning the CdS QD wet gel, and the diameter and length of the fibers were approximately 110 nm and several hundred micrometers, respectively. The nanofiber formation of CdS QDs from a wet gel provides a strategy for the creation of quantum nanowires.