Transcript Topic_4_-_Societal_Impact

The Status of Solid-State Chemistry:
Societal Impact
Nanoscience, Health, Energy, National Security,
Technology, Environment
Panelists:
Bill Buhro (Wash. U.) – panel chair
Dan Giammar (Wash. U.) – environment
Jennifer Hollingsworth (LANL) – national defense and nanoscience
Dave Johnson (U. of OR) – thermoelectrics and semiconductor tech.
Art Nozik (NREL) – solar energy and nanoscience
Xiaogang Peng (U. of AR) – nanoscience
Sony to Unveil First Blu-ray Laptop
Tue May 16, 2006, 12:30 AM ET
Sony Corp will release the first laptop
capable of playing, editing and recording
next-generation, high-definition videos in the
Blu-ray DVD format.
• Blu-ray = 25/50
GB/disc
• DVD = 4.7/8.5
GB/disc
h
Sony, which led the development of the Bluray format, said Tuesday the new VAIO AR
Premium model will be available this summer
for $3,500. Besides the Blu-ray DVD drive, the
entertainment-oriented notebook computer
features a 17-inch display, an integrated TV
tuner, and Microsoft Corp.'s Windows Media
Center Edition operating system.
TD
In-rich InGaN QDs
Ga-rich InGaN matrix
• Blu-ray = 405-nm emission from nanostructured,
phase-separated InxGa1-xN quantum wells
Societal Impact of Solid State Chemistry
• Solid-state chemistry
• Nanoscience
• Semiconductor Technology
• Nanoelectronics
• Quantum-dot light-emitting devices
• Energy
• Environment
• National Defense
• Health
Societal Impact: Semiconductor Technology
Cu - caused fundamental
changes in processing
Solid-state chemists needed:
• More elements now used
• Number increasing rapidly
• New materials needed
High-K dielectrics
Low-K dielectrics
Diffusion barriers
Inorganic photoresists
Nanostructured
The shrinking scale of microelectronics
Chip data
from Intel
See also:
D. Normile
Science
2001
G. Moore
• Moore’s Law: transistors per chip doubles every 1.5 – 2.0 years…
• through shrinking feature sizes…
• until photolithographic patterning reaches its minimum-size limit; when’s
that?
• What’s next?
1D nanostructures for nanoelectronics
C-nanotube logic gate
(NOT gate, V inverter)
Ph. Avouris et al. Nano Lett. 2001
Crossed-nanowire FET array
(Si nanowires; “address decoder”)
C. M. Lieber et al. Science 2003
• Current interest exists in C nanotubes and semiconductor nanowires for
nanoelectronic interconnects and devices …
• FETs, SETs, p-n diodes, rectifiers, logic circuits, etc.
• Nanoelectronics by assembly of nanoscale components is in a proof-ofconcept stage
Jack Kilby: Tyranny-of-numbers problem
• Currently, nanoelectronic devices are
fabricated in a serial, one-at-time manner…
• whereas a massively parallel approach for
integration and interconnection is required
• No clear strategy yet exists for the massively
parallel integration of nanoelectronics
• Lieber – Langmuir-Blodgett assembly,
statistical interconnection
• Until this problem is solved assembly-based
nanoelectronics is just a dream
US Patent
3,138,743
• Jack Kilby – Texas
Instruments
• Nobel Prize for
Physics, 2000
• Co-inventor of the
monolithic
integrated circuit
(1958) – became the
Si microchip
Nanocrystals and Colloidal Quantum Nanostructures
II-VI and III-V Semiconductor Nanocrystals
CdE:
JACS 2001, 2002
NanoLett 2001, 2006
Angew Chem 2002
Chem. Mater. 2003
InP/As:
Nano Lett 2002
ZnE:
Nano Lett 2004
Jana et al, JACS 2003
Synthesis:
Performance, rational and green
Oxide
Semiconductor
Noble Metal
Nanocrystals
Magnetic Oxide Nanocrystals
Ag
Jana et al., Chem. Mater. 2004
Chen et al,
JACS 2005
Highly Emissive and Green Quantum Dots (QDs)
Similar Emission Color Range
Cu-ZnSeMn-ZnSe
Emission
ZnSe
350
Outstanding Stability
Cu:ZnSe 200oC
Mn:ZnSe 220oC
400
450
500
550
600
650
Wavelength (nm)
• QD Photoluminescence quantum efficiencies 50 – 90%
QD Light-Emitting Devices
Electroluminescence from QD
devices (Bawendi, 2002)
Note also social impact of SolidState Chemistry in solid-state
lighting (LEDs) and laser diodes
Stimulated emission (lasing) from QDs (Klimov,
Hollingsworth, Bawendi, 2000)
Societal Impact: Quantum Dots
Build Knowledge-Based Industry
http://www.nn-labs.com
Conference PresentationsHighest quality
• APS March Meeting,
2002-2005
Broadest
wavelength range
Large
quantities
• Narrow Gap Semiconductors,
2003
Involve K-12, and
Undergrad. Students
Societal Impact: Energy
• Thermoelectrics
• Fuel Cells – ordered
intermetallic catalysts (PtBi)
• Solar-energy conversion
(photovoltaics)
• Solid-state inorganic
• Si, CuInSe2 cells
• Semiconductor liquidjunction cells
• Nanostructured:
• Dye-sensitized (Grätzel) cells
• Hybrid semiconductororganic cells
• Multiple Exciton Generation
(MEG) in QDs
Societal Impact:
Thermoelectric Materials
Thermoelectrics have both
cooling and power generation
uses
Currently used in small cooling
applications and remote
power generation (space
probes)
Potentially large impact if new
materials with enhanced
efficiency can be found
Two challenges;
Optimize electrical properties
Minimize thermal conductivity
Societal Impact:
Thermoelectric Materials
Fundamental challenges:
• parameters interrelated
• Current models present
synthetic challenges:
• Phonon-glass/electroncrystal model
• Complex unit cells
• Nanostructured
materials
• AgPb10SbTe12
• ZT > 2 (> 700 K)
• Kanatzidis (2004)
Projected Need for Carbon-Free Primary Power
Hoffert et. al. Nature 395, 881, 1998; and Science 298, 981, 2002
Bottom Line: New “disruptive” energy technology is needed
PV Power Costs as Function of Module Efficiency and Cost
From Martin Green
min BOS
Ultimate
Thermodynamic
limit
at 1 sun
ShockleyQueisser limit
For PV or PEC to provide the full level of C-free energy required for electricity
and fuel—solar power cost needs to be ~2 cents/kWh ($0.40/Wp)
Consequences of Size Quantization
in Semiconductor QDs
 Dramatic variation of optical



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

and electronic properties
Large blue shift of absorption
edge
Discrete energy
levels/structured absorption
and photoluminescence
spectra
Enhanced photoredox
properties for photogenerated
electrons and holes
PL blinking in single QDs
Slowed relaxation and cooling
(~10X) of photogenerated hot
electrons and holes (excitons)
Enhanced Auger processes
(including exciton
multiplication)
 Conversion of indirect
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



semiconductors to direct
semiconductors or vice versa
Greatly enhanced exciton
absorption at 300 K
Greatly enhanced oscillator
strength per unit volume
(absorption coefficient)
Greatly enhanced non-linear
optical properties
Greatly modified pressure
dependence of phase changes
and direct to indirect
transitions
Efficient anti-Stokes
luminescence
3rd Generation Photon Conversion
Valid Thermodynamic Approaches to Achieve Photon
Conversion Efficiencies > 32%
(Exceeds the Shockley-Queisser Limit at low cost)
1.
2.
3.
4.
5.
Tandem Cells (exceed S-Q limit but very expensive)
Hot Carrier Conversion
a. Extract, collect, and utilize hot carriers
b. Impact ionization/multiple exciton generation
(MEG)*
Intermediate Band Solar Cell
Thermophotonic Solar Cells
Down conversion and upconversion of incident
photons (M. Green and P. Wuerfel)
See:
M. Green, “Third Generation Photovoltaics”. Springer, 2003
A. Marti and A. Luque, “Next Generaton Photovoltaics”, Inst.
Of Physics Series in Optics and Optoelectronics, 2002
Red ≡ Nanostructures (quantum dots) can provide a path, and *
indicates recent breakthrough
MEG and quantum efficiencies in QDs
NREL
LANL
• PbSe and PbS QDs
• Generation of 7 concurrent excitons – which is not the limit
• Predict much higher solar-cell efficiencies if these carriers can be
separated and collected
Configurations for QD and nanowire solar cells
Nozik, 2005
• ZnO-nanowire dyesensitized cell (P. Yang,
2005)
• Enhance electron diffusion
length by replacing
nanoparticle film with
oriented single-crystal
wires
Environmental Impacts:
Size Effects on Environmental Behavior
– adsorption
– oxidation-reduction
– catalysis
Nanoscale Size Affects Chemical Reactions
– quantum effects on (photo)catalysis
– altered surface regions dominant
– enhanced apparent solubility
1600
Specific Surface Area (m2/g)
Large Surface Area/Mass Benefits Interfacial
Reactions (solid-water and solid-gas)
TiO2 ; Density = 4.2 g/cm3
1400
1200
1000
800
600
400
200
0
1
10
100
1000
Particle Diameter (nm)
Nanoscale Size Enables New Applications
– transport solid reactants in subsurface (e.g.,
groundwater)
– incorporation in membranes
– sensors for environmental systems
Banfield and Zhang, 2001, in
Nanoparticles and the Environment,
10000
Environmental Impacts:
Applications of Nanostructure Materials
Treatment and Remediation
– engineered reactors
• adsorbents for water and exhaust gas treatment
– higher capacity (mass basis) but not necessarily greater
affinity
• photocatalytic degradation of contaminants
– in situ remediation
• deliver of zero-valent iron nanoparticles to groundwater
to reduce contaminants
– transport requires surface-modifications for stability
– hybrid inorganic-organic membranes
• improve flux and inhibit fouling
Pollution Prevention (Life-Cycle Analysis)
– reduce material and energy inputs in manufacturing
– minimize volume of waste stream
Environmental Risk Assessment
– enhanced surface reactions and transport may pose new
risks
– avoid past mistakes (e.g., CFCs, DDT, tetraethyl lead)
– early studies indicate few unusual risks
Masciangioli and Zhang, 2003
Environmental Science & Technology
Environmental Impacts:
Challenges and Opportunities
Match the Scales of Reaction and Transport
– access to reactive surfaces can be limited by diffusion
• example: adsorbents must facilitate water flow and provide access to surface area
– delivery of nanoparticles to environmental field sites
• example: zero valent iron for reduction of chlorinated solvents and other contaminants
– stabilization of nanoparticles to enhance transport can inhibit reactivity; deliver reactivity to
optimal locations
Elucidate Reaction Mechanisms in Environmental Systems
– underlying mechanisms for presence or absence of size effects remain elusive
• example: why do nanoparticles have lower adsorption capacities and affinities than largerscale materials?
– integrated experimental evaluation of reactions, material characterization, and
molecular simulation
– aquatic and atmospheric environments are complex multi-component systems
Dynamic Nature of Nanostructured Materials in Aqueous Systems
– crystalline phase changes with time
• phase transformations influenced by interfacial energetics
– nanoparticle aggregation
• aggregates may not exhibit chemical or physical nanoscale properties and
• can inititiate phase transformation
National Security: Intelligence Community
Utilizes Nanoscience
• Intelligence Community requires new means for monitoring assets and collecting/
analyzing data
 Optical/acoustic receivers
 Chem/bio sensors
 Micro power supplies
 Enhanced computing
 Stealth communication
• CIA-sponsored Postdoctoral Research Fellowship Program turns, in part, to
nanoscience:
 Fluorescent Nano-Particles for High Efficiency, Portable Bio/Chem Sensors: using nanometal-enhanced fluorescence
 Spectrally Adaptive Nanoscale IR Sensors: QD-based mid-IR sensors for monitoring
chemical agent production facilities, identifying geographical terrain, etc.
 Quantum Dot Stability and Emission Efficiency: Optical markers for tagging a variety of
physical assets
 High Frequency Applications of Carbon Nanotubes (from rf to microwave frequencies):
Nanoscale antennas for wireless connection between a nanoscale device and a macroscopic
one
 Nano- to Micro-Scale Power Sources: Portable electronics, e.g., distributed sensing and
communications technology limited by the power source, requires new micro-fuel cells,
micro-photovoltaic cells, or microthermoelectric cells.
 Nanoscale Spectroscopy of Qubits for a Solid-State Quantum Computer: Searching
databases and factoring large numbers (Qubit = a nanoscale object – e.g., the charge on a
quantum dot, the polarization of a photon, or the nuclear spin state of an individual atom)
Defense Community Sponsors
Nanoscience Research
• MIT charged by U.S. Army to create a 21st century battlesuit that “combines hightech capabilities with light weight and comfort” (2002 $50 million contract)
• Research areas:
 Energy Absorbing Materials (polymers)
 Mechanically Active Materials and Devices
(adaptive/multifunctional;
polymer+magnetic actuators)
 Sensing and Counteraction
(dendrimer+nanocrystal chem/bio
sensors+neutralizers)
 Biomaterials and Nanodevices for Soldier
Medical Technology (sensing+auto delivery
of medications, load-transfer+variableimpedence devices)
 Processing and Characterization - The
Nanofoundries (enabling fiber,
microfluidics+ layer deposition
technologies)
 Modeling and Simulation of Materials and
Processes (of new materials+processes)
 Systems Design, Hardening, and
Integration (intra-team+team-army
communication)
Institute for Soldier Nanotechnologies
Nanoscience Supports DOE Mission:
National, Economic, and Energy Security
•
Five new nanoscience centers for the “synthesis,
processing, fabrication, and analysis of materials
at the nanoscale:”
 The Center for Integrated Nanotechnologies at
Sandia and Los Alamos National Laboratories
 Lawrence Berkeley National Laboratory's Molecular
Foundry
 The Center for Functional Nanomaterials at BNL
 The Center for Nanophase Materials Sciences at Oak
Ridge National Laboratory
 The Center for Nanoscale Materials at Argonne
National Lab
•
E.g., Nanocrystal Quantum Dots find national-security relevant applications at LANL:
High efficiency solar cells
Solid state lighting
Assets marking/detection
Societal Impact: Health
Biological labeling and detection with
QDs. Uses:
• Immunofluorescent probes for Her2
breast-cancer marker
• In immunoassays microbial toxins
• Labels in cancer-cell-motility studies
• During surgery to map lymph nodes
• Virus detection:
• Respiratory Syncytial Virus (RSV)
• D. W. Wright, Nano Lett. 2005
1h
QD RSV detection fast and
sensitive:
• QD detection in 1 h
• Western blot: > 96 h
• Real-time PCR: early
response near detection
limit
96 h
Societal Impact of Solid State Chemistry
• Solid-state chemistry
• Nanoscience
• Semiconductor Technology
• Nanoelectronics
• Quantum-dot light-emitting devices
• Energy
• Environment
• National Defense
• Health