Colloidal quantum dot solids and devices
Our interest in colloidal semiconductor quantum dots (QDs) stems from their size-tunable properties, unique photophysics (e.g., multiple exciton generation), and ability to be self-assembled from solution into functional films for optoelectronics. Our work is vertically integrated, encompassing QD synthesis, film fabrication via self-assembly, ligand and surface chemistry studies, structural characterization, fundamental investigations of charge transport using a variety of experimental approaches (field-effect transistors, Hall effect), and fabrication, characterization and modeling of QD-based devices such as solar cells, photodetectors and transistors. A major goal of the QD sub-group is to fabricate QD solids with sufficient spatial and energetic order to trigger the emergence of electronic mini-bands that offer high carrier mobility and long diffusion length with controlled doping, as is necessary for making high-performance QD optoelectronic devices.
The slide above summarizes some of our ongoing work in this field. The videos below show (left) the conversion of an oleate-capped PbSe QD superlattice into an epitaxially-fused superlattice and (right) an electron tomography reconstruction of a 120 × 38 nm disc-shaped region of a PbSe QD epi-superlattice at 0.65 nm resolution.