Just a quick reminder of the talk on Si/perovskite tandems tomorrow at
noon.
Light refreshments will be served.
On Wed, May 10, 2017 at 2:23 PM Catherine M Bourgeois <cmbourg(a)mit.edu>
wrote:
Please post and forward to your group(s).
*CENTER FOR EXCTIONICS presents:*
Perovskite Tandems: A Path Towards Stable 27% Efficiencies*
May 17, 2017 at 12 noon/RLE Haus room: 36-428
*Axel Palmstrom*
*Stanford University*
[image: image001.jpg]
Hybrid lead halide perovskites are promising candidates for low cost, thin
film light absorbers; they have a tunable band gap and have demonstrated
efficiencies as high as 22.1%. As such, these materials are of interest for
wide-bandgap absorbers in tandem photovoltaics. Hybrid lead halide
perovskites are soft materials with rough surfaces and are sensitive to
temperature and oxidative conditions, making many deposition processes
incompatible with this material. Typical perovskite solar cells employ
spin-deposited organic selective transport layers and evaporated metal
contacts on top of the perovskite absorber. These organic selective
transport layers have a few main drawbacks for tandem solar cells: first,
the rough perovskite surface requires thick organic layers for complete
coverage, resulting in significant optical losses, second, these organic
materials are incompatible with the types of sputter processes used to
deposit high quality transparent contacts (such as indium-tin oxide) and
third, organic materials are typically poor elemental diffusion barriers;
such barriers are important for device stability. We applied tin oxide by
atomic layer deposition (ALD) as a dual-purpose layer to achieve electron
selectivity and sputter protection with high optical transmission in
monolithic perovskite/silicon and perovskite/perovskite tandem devices.
I look at methods to push perovskite tandem efficiencies to 27% and beyond
through targeted short circuit current density, fill factor and open
circuit voltage enhancements while maintaining a stable device
architecture. I will focus on the perovskite-tin oxide interface on a range
of perovskite compositions. Here I investigate the role of organic surface
passivation layers and ALD processing conditions on perovskite degradation
and interface energetics, which ultimately affects device open circuit
voltage, a key figure of merit towards achieving stable 27% efficient
devices.
*Axel Palmstrom* is a graduate student at Stanford University in the
group of Stacey Bent pursuing his Ph.D. in Chemical Engineering. He
graduated with Highest Honors from the University of California, Santa
Barbara in 2012 with a B.S. in Chemical Engineering. His work focuses on
the study metal oxide thin films grown by atomic layer deposition for
applications in thin film photovoltaics, including electron and hole
selective layers, barrier layers and surface passivation.
**This talk is part of the Perovskites Seminar Series organized by
Juan-Pablo Correa-Baena from MIT’s PV Lab and sponsored by the Center for
Excitonics. For more info contact Juan-Pablo: **jpcorrea(a)mit.edu*
<jpcorrea(a)mit.edu>
*The Center For Excitonics Is An Energy Frontier Research Center Funded By
The U.S. Department Of Energy,*
* Office Of Science And Office Of Basic Energy Sciences*
Light refreshments will be served.
--
Juan-Pablo Correa-Baena, PhD
Postdoctoral Researcher
Massachusetts Institute of Technology (MIT)
Cambridge, MA, USA
E: jpcorrea(a)mit.edu
W:
http://pv.mit.edu/