Multilayers of CdSe Nanocrystals and Bis-Dithiocarbamate Linkers Displaying Record Photoconduction

Bis(dithiocarbamate) molecules were reacted with (hexadecylamine/ stearate)-capped CdSe nanocrystals (7.5 nm diameter) to form multilayers on ITO glass via layer-by-layer alternation. The new materials were investigated by UV-vis and FTIR spectroscopy, photoluminescence, and photoconductivity. FTIR and UV-vis analysis of multilayers showed that the bis(dithiocarbamate) linkers operate the complete removal of caps and cover the nanocrystal layer (ca. 2 × 10-8 mol cm-2 layer-1 in CdSe units) with a dense linker layer (ca. 2 × 10-9 mol cm-2 layer-1). The photoconductivity of the multilayer films obtained with such linkers is strongly enhanced, compared with analogous films produced with bis(carboxylate) linkers of comparable length and structure, attaining record values 10-100 times higher.