Colloidal synthesis forms the backbone of our research. In addition to enabling deeper physical insight in spectroscopic and transport studies and producing superior devices, synthetic advances such as shape control, charge (doping) control, passivation of undercoordinated surface atoms etc. are themselves important for the wider field of colloidal inorganic chemistry. Past synthesis-related milestones from the group include the introduction core/shell nanocrystal heterostructures, first chemical reduction (n-doping) of nanocrystals, elucidation of gold nanoparticle growth mechanisms, synthesis of superconducting metal nanoparticles, and the introduction of size-tunable HgTe nanoparticles for infrared optoelectronics.

The group currently focuses on the mercury chalcogenide (HgX, X = S, Se, Te) family of nanocrystals with infrared energy gaps in the 0.1 – 0.6 eV (2000 – 10000 nm wavelength) range. Synthetic efforts focus on improving the nanoparticle size distributions,  growing novel HgX/MX (M = metal) heterostructures and controlling the doping. The doping control and associated surface chemistry present especially rich challenges in HgX systems due to their small energy gaps. This allows chemical perturbations which are usually inconsequential to produce sizable effects, rendering HgX a unique platform for the study of nanoparticle interfacial chemistry.

Selected publications

• Toward Bright Mid-infrared Emitters: Think-shell n-Type HgSe/CdS Nanocrystals J. Am. Chem. Soc. 2021
• Shape-controlled HgTe colloidal quantum dots and reduced spin–orbit splitting in the tetrahedral shape J. Phys. Chem. Lett. 2020
• Quantum dot solids showing state-resolved band-like transport Nat. Mater. 2020
• HgTe/CdTe and HgSe/CdX (X = S, Se and Te) core/shell mid-infrared quantum dots Chem. Mater. 2019
• Conduction band fine structure in colloidal HgTe quantum dots ACS Nano 2018
• Synthesis of nonaggregating HgTe colloidal quantum dots and the emergence of air-stable n-doping J. Phys. Chem. Lett. 2017
• HgS and HgS/CdS colloidal quantum dots with infrared intraband transitions and the emergence of a surface plasmon J. Phys. Chem. C 2016
• Synthesis of colloidal HgTe quantum dots for narrow mid-IR emission and detection J. Am. Chem. Soc. 2011
• Mechanism of silver (I)-assisted growth of gold nanorods and bipyramids J. Phys. Chem. B 2005
• Organic-capped ZnO nanocrystals: synthesis and n-type character J. Am. Chem. Soc. 2001
• n-type colloidal semiconductor nanocrystals Nature 2000
• Synthesis and characterization of strongly-luminescing ZnS-capped CdSe nanocrystals, J. Phys. Chem. 1996