Spin-coated fluorinated PbS QD superlattice thin film with high hole mobility
Pan Xia1, Daniel W Davies2, Bijal B Patel2
1Department of Chemistry & Materials Science and Engineering Program, University of California, Riverside, 900 University Avenue, Riverside, California 92521, USA. mltang@ucr.edu.
Abstract:
Motivated by the oleophobic and electron-withdrawing nature of perfluorocarbons, we explore the effect of a trifluoromethyl coating on lead sulfide quantum dots (PbS QDs) in thin film transistor (TFT) geometry. The low surface energy conferred by the oleophobic perfluorocarbons creates QDs packed in a primitive cubic lattice with long range order, as confirmed by grazing incidence small angle X-ray scattering (GISAXS) and transmission electron microscopy (TEM). Hole mobilities as high as 0.085 cm2 V-1 s-1 were measured in the TFTs. No electron transport was observed. This suggests that the electron-withdrawing nature of the trifluoromethyl ligand is eclipsed by the excess holes present in the PbS QDs that likely stem from cation vacancies induced by the thiol group.
