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.

Selected Publications

Collective topo-epitaxy in the self-assembly of a 3D quantum dot superlattice.
Abelson, A., Qian, C., Salk, T., Luan, Z., Fu, K., Zheng, J.-G., Wardini, J. L., Law, M. Nature Materials, 19, 49-55 (2020) PDF  Online Article

Structural characterization of a polycrystalline epitaxially-fused colloidal quantum dot superlattice by electron tomography.
Chu, X., Heidari, H., Abelson, A., Unruh, D., Hansen, C., Qian, C., Zimanyi, G., Law, M., Moule, A. J. Journal of Materials Chemistry A, 8, 18254-18265 (2020) PDF  Online Article

Dynamic deformability of individual PbSe nanocrystals during superlattice phase transitions.
Wang, Y., Peng, X., Abelson, A., Xiao, P., Qian, C., Yu, L., Ophus, C., Ercius, P., Wang, L.-W., Law, M., Zheng, H. Science Advances, 5, eaaw5623 (2019) PDF  Online Article

PbSe quantum dot field-effect transistors with air-stable electron mobilities above 7 cm2 V-1 s-1.
Liu, Y., Tolentino, J., Gibbs, M., Ihly, R., Perkins, C. L., Liu, Y., Crawford, N., Hemminger, J. C., Law, M. Nano Letters, 13, 1578-1587 (2013) PDF  Online Article

Robust, functional nanocrystal solids by infilling with atomic layer deposition.
Liu, Y., Gibbs, M., Perkins, C. L., Zarghami, M. H., Bustamante, Jr., J., Law, M. Nano Letters, 11, 5349-5355 (2011) PDF  Online Article

Dependence of carrier mobility on nanocrystal size and ligand length in PbSe nanocrystal solids.
Liu, Y., Gibbs, M., Puthussery, J., Gaik, S., Ihly, R., Hillhouse, H. W., Law, M. Nano Letters, 10, 1960-1969 (2010) PDF  Online Article

Emergence of distinct electronic states in epitaxially-fused PbSe quantum dot superlattices.
Kavrik, M. S., Hachtel, J., Ko, W., Qian, C., Abelson, A., Unlu, E. B., Kashyap, H., Li, A.-P., Idrobo, J.-C., Law, M. Nature Communications, 13, 6802. (2022) PDF  Online Article

Photobase-triggered formation of 3D epitaxially-fused quantum dot superlattices with high uniformity and low bulk defect densities.
Qian, C., Abelson, A., Miller-Casas, A., Capp, R., Vinogradov, I., Udagawa, N. S., Ge, N.-H., Law, M. ACS Nano, 16, 3239–3250 (2022) PDF  Online Article

Atomic lattice-resolved electron tomography of a 3D self-assembled mesocrystal.
Chu, X., Abelson, A., Qian, C., Igouchkine, O., Field, E., Ma, K.-L., Law, M., Moule, A. J. Advanced Functional Materials, 2301026 (2023) PDF  Online Article

High-mobility hole transport in single-grain PbSe quantum dot superlattice transistors.
Abelson, A., Qian, C., Crawford, Z., Zimanyi, G. T., Law, M. Nano Letters, 22, 9578–9585 (2022) PDF  Online Article

Elimination of the bias-stress effect in ligand-free quantum dot field-effect transistors.
Tolentino, J., Gibbs, M., Abelson, A., Law, M. The Journal of Chemical Physics, 159, 044709 (2023) PDF  Online Article