Download Bulovic

Organic and Nanostructured Electronics Lab
Vladimir Bulović
Mission Facili.es and Unique Approaches We are large-area nanotechnologists developing practical
devices and structures from physical insights discovered at
the nanoscale. Our work demonstrates that nanoscale
materials such as molecules, polymers, and nanocrystal
quantum dots can be assembled into large area functional
optoelectronic devices that surpass the performance of
today's state-of-the-art. We combine insights into physical
processes within nanostructured devices, with advances in
thin film processing of nanostructured material sets, to
launch new technologies and glimpse into the polaron and
exciton dynamics that govern the nanoscale.
The ONE Lab supports over 60 users with various micro- and nano-fabrication and
characterization instruments and equipment, including solar cell testing systems, thermal
evaporation and sputtering chambers for deposition of organics, metals, and oxides, and
optical lab space with wavelength-tunable, high power sub-picosecond laser.
The research group consists of members of diverse research interests and experiences,
creating a conducive environment for collaborative work.
Photonic
Materials,
Devices, and
Systems
Nanoscale
Science
and
Engineering
Quantum Dot Light EmiJng Diodes (QDLEDs) The stable, highly saturated emission and tunable bandgap of solution-processed colloidal quantum dots (QDs)
make them useful for light-emitting devices.
Energy, Power and
Electronics
Quantum Dot Photovoltaic (QDPVs) With band-gaps tunable from 0.5 to 2.1 eV,
PbS and PbSe QDs offer infrared spectral
responsivity surpassing that of organic
materials, making these QDs promising for
use as absorptive layers in PVs.
Field Driven Electroluminescence The dynamics of charge transport
within the QD layer are studied using
electrical and spectroscopic
measurements to determine the main
limitations of device performance in
QDLEDs.
Ligand Exchange in PbS QDs QD surfaces are passivated with organic
ligands. By tuning the ligand length and
functionality we can optimize the transport
properties and interfacial energetics of QD
solids.
ZnO Nanowire QDPVs ZnO nanowire transport layer
decouples absorption from
collection, extending the effective
depletion width throughout a
thick QD film.
Progress is rapid and promising:
Engineering energy barriers Op4mal mul4junc4on subcell bandgaps: Metal oxide transport layers are used to
remove barriers to electron extraction.
Brown, P.R. et al, “Improved current extrac4on from ZnO/PbS quantum dot heterojunc4on photovoltaics using MoO3 interfacial layer,” Nano Le(. 11, 2955 (2011). Brown, P.R. et al. ACS Nano, in prep. Bozyifit, D et al, “Study of Field Driven Electroluminscence in
Colloidal Quantum Dot Solids,” J. App. Phy., 113701 (2012).
Coupled J-aggregating molecules
exhibit high absorption, narrow
emission, and small Stokes shift.
!#
DF)..9,.)/,1,3;77;8-
2.0
SJ2
MJ
0.0
-2.5
-5.0
-7.5
-0.5
0.5
1.0
Voltage ( V )
1.5
&#
#
!"#
DBP
1.5
ClAlPc
G8-83,91)6789:/;8-
A;B/01C1%'1-3
0.5
2.0
"##
""#
()*+,-./012-34
$##
$"#
Fluorescence Enhancement The fluorescence of the organic
dye DCM is enhanced when
resonantly coupled to a strongly
optically absorbing structure
consisting of a thin film of
molecular J-aggregates in a critically
coupled resonator.
J-­‐Aggregate Photo-­‐detector 1.0
0.0
0.0
'#
%#
5.0
SJ1
DE)..9,.)/,1)6789:/;8-
=08/8+>3;-,7?,-?,1;-/,-7;/@
Stacked multijunction photovoltaics
take advantage of narrow
absorption features in organics and
non-spatially-uniform optical
intensity to more efficiently utilize
the broadband solar spectrum.
2.5
J-­‐aggregates and Op.cal Devices 56789:/;8-12<4
Noncontact-­‐based nanoelectromechanical switches
operate via
tunneling/
percolation
through a
compressible
organic layer
controlled by
electrostatically
driven
mechanical
compression.
Mul.junc.on Organic PV Extinction Coefficient
Thin (~100 nm) gold membranes on
cavity-patterned silicon dioxide substrates
are fabricated for MEMS applications.
Squeezable Switch (Squish) 2
Contact Printed Gold Membrane Organic Photovoltaics (OPVs) Current Density ( mA/cm )
Microelectromechanical Systems (MEMS) Jean, J. et al, “ZnO Nanowire Arrays for Enhanced Photocurrent
in PbS Quantum Dot Solar Cells,” Adv. Mat., in prep.
C60
400
500
600
700
800
900
Wavelength ( nm )
Macko, J. et al, “Multijunction Organic Photovoltaics with a Broad Spectral Response,” Phys. Chem.
Chem. Phys. (2012).
With their narrow absorption
features, J-aggregates can be used to
fabricate wavelength-resolved thin-film
photodetectors.
Organic PV on paper substrates In collaboration with the Gleason group in chemical
engineering we fabricate functional organic PVs on paper.
Murarka, A. et al, “Printed MEMS Membranes on Silicon,” MEMS, 2012
IEEE Int. Conf., 309 (2012) .
Paydavosi, S. et al, “MEMS Switches Employing Active Metal-polymer
Nanocomposites,” MEMS, 2012 IEEE Int. Conf., 180 (2012) .
Barr, C. et al, “Direct Monolithic Integration of Organic Photovoltaic Circuits on Unmodified
Paper,” Adv. Mat. 23, 3500 (2011).
Osedach, T. et al, “Near-infrared Photodector Consisting of Jaggregating Cyanine Dye and Metal Oxide Thin Films,” App.
Phy. Lett. 101, 113303 (2012).
Akselrod, G. et al, “20-fold Enhancement of Molecular
Fluorescence by Coupling to a J-Aggregate Critically Coupled
Resonator,” ACS Nano 6, 467 (2012).
The ONElab Team Dr. Ronny Costi, Dr. Parag Deotare, Dr. Dong Kyun, Dr. Andrea Maurano, Dr. Tim Osedach, Dr. Annie Wang
Gleb Akselrod, Patrick Brown, Wendi Chang, Matthew D’Asaro, Eletha Flores, Christina Hanson, Joel Jean, Jill Macko, Thomas Mahony,
Apoorva Murarka, Farnaz Niroui, Yasuhiro Shiradaki, Katherine Song, Supran, Mun Ee Woo.