Ligand effects on electronic and optoelectronic properties of two-dimensional PbS necking percolative superlattices
nanocrystals, necking percolative superlattices, ligand, mobility, trap states
ABSTRACT The inter-nanocrystal (NC) distance, necking degree, ordering level, and NC surface ligands all affect the electronic and optoelectronic properties of NC solids. Herein, we introduce a unique PbS structure of necking percolative superlattices to exclude the morphological factors and study the effect of ligands on the NC properties. X-ray photoelectron spectroscopy data indicate that 1,2-ethanedithiol (EDT), oxalic acid, mercaptopropionic acid, and NH4SCN (SCN) ligands were attached to the surface of NCs by substrate-supported ligand exchange. Field-effect transistors were tested and photodetector measurements were performed to compare these NC solids. An SCN-treated film had the highest mobility and responsivity under high-power intensity irradiation owing to its high carrier density, whereas an EDT-treated film had the lowest mobility, photocurrent, and dark current. These findings introduce new avenues for choosing suitable ligands for NC applications.
Tsinghua University Press
Man Zhao,Defang Ding,Fangxu Yang,Dawei Wang,Jiawei Lv,Wenping Hu,Chenguang Lu,Zhiyong Tang, Ligand effects on electronic and optoelectronic properties of two-dimensional PbS necking percolative superlattices. NanoRes.2017, 10(4): 1249–1257