Research in the Weiss Group
Department of Chemistry
Northwestern University
2016
Classes of Solar Energy Conversion
Photovoltaic
Photocatalytic
Solar Thermal/Thermoelectric
www.openfuelstandard.org
At the Microscopic Level…
conversion of excited states to mobile charge carriers
+
-
-
migration of energy and charge carriers
+
-
collection of charge carriers
V
-
-
+
redox-driven chemical
reactions
+
Energy exchange between electronic and vibrational oscillators
-
The Role of Interfaces in Energy Conversion
- To connect the energy conversion process to the macroscopic world
- To provide gradients in free energy (chemical or electrical potentials) to drive energy conversion processes
McEuen and co-workers, Nano Lett., 10 (2010)
Nanostructured materials have a high density of interfaces
- large flux of energy and charge between nanoscale components
How can we use chemistry to best exploit the interfacial area within nanostructured materials
for energy conversion
PLUS…
(and minimize loss)?
- solution processible inorganics
- size-tunable excited state energies
- plasmons
Semiconductor nanocrystals, aka, Quantum Dots
20 nm
e-
Bohr “Radius” ≈ 5.9 nm (CdSe)
2 – 6 nm
QD
50 nm
h+
SAMs on Nanoparticles as Molecular
Recognition Layers
Spectral and Spatial Control of Excitons
within Quantum Dot-Molecule
Assemblies
Raman Shift
Dissipation of Electronic Energy into
Vibrations at Nanoscale Interfaces
Electron Ratchets
Photocatalysis with Quantum Dots
Photocatalysis
QDs as catalysts for water
oxidation, proton reduction, CO2
reduction, organic transformations
Synthesis • NMR • Transient Absorption
Energy Dissipation at
Interfaces
Control of electronic-to- vibrational
energy transfer at QD and NP
surfaces?
FTIR • NIR and mid-IR Transient Absorption •
Calculations
New Modes of Charge
Transport
Electronic Ratchets
Synthesis • Photoelectrical Measurements •
Fabrication • Quantum Dynamics
SAMs as Molecular Recognition Layers
on Nanoparticles
Interfacial charge transfer, self-assembly, interparticle
interactions, sensing
Manipulation of Excitons
in QD-Organic Assemblies
Up- and down-conversion
processes, energy transport
Synthesis • New Separation Techniques• Selfassembly • Spectroscopy
Key Skill-Sets
-Solution-phase
and purification of nanoparticles and imaging (TEM)
-
(linear/non-linear; electronic/vibrational)
-Ground-state
-
(absorption/fluorescence/Raman)
on colloid surfaces (ICP, NMR, XPS, EDX)
-Time-correlated single
SEM)
(time-resolved PL)
deposition, characterization (AFM, ellipsometry,
Quantum dynamics, molecular
dynamics, electronic structure
http://sites.weinberg.northwestern.edu/weiss-lab/
Full group meetings: Thursdays 10-11:30, Tech K140
Subgroup meetings: Check group calendar
OPEN HOUSE!! September 29th 5-7 PM
Willens (B) Wing Atrium – above IMSERC