About

Emily A. Weiss is a Professor of Chemistry and the Irving M. Klotz Research Professor at Northwestern University. Her research focuses on the fundamental physical chemistry of colloidal semiconductor quantum dots in both solution and solid phases. She aims to map the surface chemistry of nanocrystals to their optical and electronic properties, studying mechanisms of energy dissipation such as radiative and non-radiative decay, energy transfer, and charge transfer. Her work involves using various structural, analytical, optical, and electrical characterization methods, including ultrafast transient absorption, time-resolved photoluminescence, coherent anti-Stokes Raman spectroscopy, and current-voltage measurements. Weiss's goal is to understand how organic ligands can be used to control these energy pathways.

Research topics

• Nanotechnology
• Chemistry
• Photochemistry
• Organic chemistry
• Chemical engineering
• Materials science
• Condensed matter physics
• Physics
• Inorganic chemistry
• Atomic physics
• Optoelectronics
• Chemical physics

Selected publications

• Enhanced spectral purity of WSe ₂ quantum emitters via conformal organic adlayers

  Science Advances · 2025-10-03 · 3 citations

  articleOpen access

  Quantum emitters in solid-state materials are typically embedded in the bulk of their hosts, making their electronic transitions inaccessible to surface modification. In contrast, two-dimensional materials, with their all-surface nature, offer a platform for tuning quantum emitters via chemical functionalization. Because of its semiconducting properties that enable electrical addressability, monolayer WSe 2 is a promising candidate for quantum emission, although the complex interplay between point defects and the localized strain needed to activate quantum emission leads to poor spectral purity. Here, we demonstrate that functionalizing monolayer WSe 2 with conformal adlayers of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) improves quantum emission spectral purity. Optical spectroscopy reveals that PTCDA functionalization lowers defect activation energies by 10 meV and induces a 30 nm redshift in quantum emission wavelength, while preserving the bright and dark exciton energies of monolayer WSe 2 . First-principles calculations corroborate these findings, thus providing molecular-level insight into the underlying mechanism of enhanced spectral purity.

  PublisherDOI

• Carbene Functionalization of Monolayer Tungsten Disulfide for Enhanced Quantum Emission

  ACS Nano · 2025-06-03 · 7 citations

  article

  Semiconducting two-dimensional (2D) transition metal dichalcogenides (TMDs) are promising materials for an array of applications, ranging from conventional field-effect transistors, photodetectors, and light-emitting diodes to their more recent use in quantum photonic technologies. Chemical functionalization of 2D TMDs with organic ligands and adlayers provides an additional means for customizing their electronic and optical properties. While many pathways have been reported for the chemical functionalization of 2D TMDs, their frequent reliance on solution-based methods results in limited control over adlayer thickness and coverage, thus hindering utility in high-performance applications. Here we describe the vapor-phase functionalization of a 2D TMD with carbene ligands, specifically tungsten disulfide (WS2) with N-heterocyclic carbenes (NHCs), resulting in molecularly smooth, thin, and uniform adlayers. Reacting NHCs with monolayer WS2 reduces the broad photoluminescence background observed at cryogenic temperatures by 58%, which facilitates the detection of single-photon emitters from strained monolayer WS2, as indicated by second order correlation values (g(2)) as low as 0.17 ± 0.07. Chemical characterization coupled with density functional theory calculations suggests that the NHC adlayer has a dual defect-passivation and doping effect on monolayer WS2 that results in enhanced single-photon emission. Overall, this study establishes vapor-phase carbene functionalization as a homogeneous surface modification scheme for tailoring the quantum emission properties of semiconducting 2D TMDs.

  PublisherDOI

• Slowing Hot Electron Cooling in CdSe Quantum Dots Using Electron‐Rich Exciton‐Delocalizing Ligands

  ChemPhotoChem · 2024-01-01 · 5 citations

  articleOpen access

  Abstract Understanding hot carrier dynamics in semiconductor nanocrystals is an important research focus due to their applications in photonics and photovoltaic devices. In this report, we investigated the effects of surface‐bound exciton‐delocalizing ligands (EDLs) on the lifetimes of hot electrons in CdSe quantum dots (QDs). After treatment of CdSe with two different phenylithiocarbamates (PTCs), a class of EDLs, the depletion times of the band‐edge exciton bleach were roughly equivalent as observed through ultrafast transient absorption spectroscopy. However, following the initial ultrafast depletion, the PTC‐treated samples continued to deplete while the untreated CdSe began recovering. Inspection of other transient features – such as the 3 rd exciton and hot biexciton – reveal a general trend in which the PTC‐treated samples relax more slowly at short times (<10 ps) when compared with the untreated CdSe. At longer delay times, in the range of nanoseconds, the CdSe+CF 3 OPTC loses nearly 80 % of its excited state populations, while the CdSe+MeOPTC loses only 20–40 %. We discuss the role that exciton delocalization plays in determining these observed rates as well as how they compare to previous studies. Kinetic differences between the two ligands are attributed to their electron donating/withdrawing abilities and coupling to the CdSe QD. Coherent vibrational wavepacket analysis supports this line of reasoning, showing increased coupling between the exciton and the longitudinal optical (LO) phonon due to increased Coulombic field strength around the hole and electron‐donating MeOPTC. These results indicate that electron‐rich PTCs are especially good candidates for use in QD devices that would make use of hot carriers.

  PublisherOA PDFDOI

• Dark State Concentration DependentEmission and Dynamics of CdSe NanoplateletExciton-Polaritons

  ChemRxiv · 2024-03-05 · 2 citations

  preprintOpen access

  The recent surge of interest in polaritons has prompted fundamental questions about the role of dark states in strong light-matter coupling phenomena. Here, we systematically vary the relative number of dark state polaritons by controlling the number of stacked CdSe nanoplatelets confined in a Fabry-Pérot cavity. We find the emission spectrum to change significantly with an increasing number of nanoplatelets, with a gradual shift of the dominant emission intensity from the lower polariton branch to a manifold of dark states. Through accompanying calculations based on a kinetic model, this shift is rationalized by an entropic trapping of excitations by the dark state manifold, while a weak dark state dispersion due to local disorder explains their non-zero emission. Our results point towards the relevance of the dark state concentration to the optical and dynamical properties of cavity-embedded quantum emitters with ramifications for Bose- Einstein condensate formation, polariton lasing, polariton-based quantum transduction schemes, and polariton chemistry.

  PublisherOA PDFDOI

• Sub‐Diffraction Correlation of Quantum Emitters and Local Strain Fields in Strain‐Engineered WSe₂ Monolayers

  Advanced Materials · 2024-02-12 · 10 citations

  articleOpen accessCorresponding

  Abstract Strain‐engineering in atomically thin metal dichalcogenides is a useful method for realizing single‐photon emitters (SPEs) for quantum technologies. Correlating SPE position with local strain topography is challenging due to localization inaccuracies from the diffraction limit. Currently, SPEs are assumed to be positioned at the highest strained location and are typically identified by randomly screening narrow‐linewidth emitters, of which only a few are spectrally pure. In this work, hyperspectral quantum emitter localization microscopy is used to locate 33 SPEs in nanoparticle‐strained WSe 2 monolayers with sub‐diffraction‐limit resolution (≈30 nm) and correlate their positions with the underlying strain field via image registration. In this system, spectrally pure emitters are not concentrated at the highest strain location due to spectral contamination; instead, isolable SPEs are distributed away from points of peak strain with an average displacement of 240 nm. These observations point toward a need for a change in the design rules for strain‐engineered SPEs and constitute a key step toward realizing next‐generation quantum optical architectures.

  PublisherOA PDFDOI

• Dark State Concentration Dependent Emission and Dynamics of CdSe Nanoplatelet Exciton-Polaritons

  ACS Nano · 2024-07-23 · 8 citations

  article

  The recent surge of interest in polaritons has prompted fundamental questions about the role of dark states in strong light-matter coupling phenomena. Here, we systematically vary the relative number of dark states by controlling the number of stacked CdSe nanoplatelets confined in a Fabry-Pérot cavity. We find the emission spectrum to change significantly with an increasing number of nanoplatelets, with a gradual shift of the dominant emission intensity from the lower polariton branch to a manifold of dark states. Through accompanying calculations based on a kinetic model, this shift is rationalized by an entropic trapping of excitations by the dark state manifold, while a weak dark state dispersion due to local disorder explains their nonzero emission. Our results point toward the relevance of the dark state concentration to the optical and dynamical properties of cavity-embedded quantum emitters with ramifications for Bose-Einstein condensate formation, polariton lasing, polariton-based quantum transduction schemes, and polariton chemistry.

  PublisherDOI

• Mixed-dimensional heterostructures for quantum photonic science and technology

  MRS Bulletin · 2023-08-15 · 9 citations

  article
  PublisherDOI

• Control of photoswitching kinetics with strong light-matter coupling in a cavity

  ChemRxiv · 2023-07-06 · 2 citations

  preprintOpen access

  Most photochemistry occurs in the regime of weak light-matter coupling, in which a molecule absorbs a photon and then performs pho-tochemistry from its excited state. In the strong coupling regime, enhanced light-matter interactions between an optical field and multiple molecules lead to collective hybrid light-matter states called polaritons. This strong coupling leads to fundamental changes in the nature of the excited states including multi-molecule delocalized excitations, modified potential energy surfaces, and dramatically altered energy levels relative to non-coupled molecules. The effect of strong light-matter coupling on covalent photochemistry has not been well ex-plored. Photoswitches undergo reversible intramolecular photoreactions that can be readily monitored spectroscopically. In this work, we study the effect of strong-light matter coupling on the kinetics of photoswitching within optical cavities. Reproducing prior experiments, photoswitching of spiropyran/merocyanine photoswitches is decelerated in a cavity. Fulgide photoswitches, however, show the opposite effect, with strong coupling accelerating photoswitching. While modified merocyanine switching can be explained by changes in radiative decay rates or the amount of light in the cavity, modified fulgide switching kinetics suggest direct changes to excited-state reaction kinetics.

  PublisherOA PDFDOI

• CCDC 2161287: Experimental Crystal Structure Determination

  The Cambridge Structural Database · 2023-02-14

  datasetOpen access

  An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  PublisherDOI

• Solution Combustion Synthesis and Characterization of Magnesium Copper Vanadates

  Inorganic Chemistry · 2023-06-01 · 14 citations

  articleOpen access

  Magnesium vanadate (MgV2O6) and its alloys with copper vanadate were synthesized via the solution combustion technique. Phase purity and solid solution formation were confirmed by a variety of experimental techniques, supported by electronic structure simulations based on density functional theory (DFT). Powder X-ray diffraction combined with Rietveld refinement, laser Raman spectroscopy, diffuse reflectance spectroscopy, and high-resolution transmission electron microscopy showed single-phase alloy formation despite the MgV2O6 and CuV2O6 end members exhibiting monoclinic and triclinic crystal systems, respectively. DFT-calculated optical band gaps showed close agreement in the computed optical bandgaps with experimentally derived values. Surface photovoltage spectroscopy, ambient-pressure photoemission spectroscopy, and Kelvin probe contact potential difference (work function) measurements confirmed a systematic variation in the optical bandgap modification and band alignment as a function of stoichiometry in the alloy composition. These data indicated n-type semiconductor behavior for all the samples which was confirmed by photoelectrochemical measurements.

  PublisherDOI

Recent grants

• Charge Transfer as a Probe of the Permeability of Organic Adlayers on Colloidal Semiconductor Quantum Dots

  NSF · $362k · 2014–2017

• A Quantum Dot Probe for Nanosecond-Timescale Imaging of Fast Biological Processes

  NIH · $417k · 2018–2021

• SusChEM: Visible Light-Driven Reduction of Carbon Dioxide using Heavy Metal-Free Colloidal Quantum Dots as Sensitizers

  NSF · $409k · 2017–2020

Frequent coauthors

• Daniel T. Chang

  800 shared

• Sylvia K. Plevritis

  600 shared

• Ivan Smirnov

  University of California, San Francisco

  600 shared

• N. Saito

  600 shared

• Kelsey Hopkins

  Purdue University West Lafayette

  600 shared

• Lih‐Shen Chin

  Shanghai University of Traditional Chinese Medicine

  600 shared

• Olivier Gevaert

  600 shared

• Tali Mazor

  University of California, San Francisco

  600 shared

Labs

• Weiss LabPI

Awards & honors

• Harry Gray Award for Creative Work in Inorganic Chemistry by…
• Camille Dreyfus Teacher-Scholar Award, The Dreyfus Foundatio…
• Kavli Emerging Leader in Chemistry, American Chemical Societ…
• NU-Argonne Early Career Investigator Award for Energy Resear…
• A.P. Sloan Research Fellowship (2011)