Electron-Conducting PbS Nanocrystal Superlattices with Long-Range Order Enabled by Terthiophene Molecular Linkers

PbS nanocrystals are surface-functionalized with the organic semiconductor 5,5 ''-dithiol-[2,2':5,2 ''-terthiophene] and assembled to afford hybrid nanostructured thin films with a large structural coherence and an electron mobility of 0.2 cm(2)/(V s). Electrochemistry, optical spectroscopy, and quantum mechanical calculations are applied to elucidate the electronic structure at the inorganic/organic interface, and it is established that electron injection into the molecule alters its (electronic) structure, which greatly facilitates coupling of the neighboring PbS 1S(e) states. This is verified by field-effect and electrochemically gated transport measurements, and evidence is provided that carrier transport occurs predominantly via the 1S(e) states. The presented material allows studying structure-transport correlations and exploring transport anisotropies in semiconductor nanocrystal superlattices.