[BNC-all] Solar Seminar by Ana Kanevce (NREL), Tuesday, April 15th, 10:30 AM - 11:30 AM, BNC 1001

[Xufeng Wang]

Dear all,

I would like to cordially invite you all to the following seminar hosted by
Network of Photovoltaic Technology (NPT) at Purdue.

Date: Tuesday, April 15th, 2014
Time: 10:30 AM - 11:30 AM
Location: Birck Nanotechnology Center (BNC) room 1001

Seminar by Dr. Ana Kanevce of the National Renewable Energy Laboratory
(NREL).

Title: "Insight into time-resolved photoluminescence measurements on
thin-film solar cells using numerical simulations "

Abstract
Increased efficiency in thin-film solar cells requires higher degree of
understanding of the recombination mechanisms, and separating the various
types of recombination involved.  Time resolved photoluminescence (TRPL)
measurement is a contactless and quick measurement method, and therefore
one of the key metrics available to determine the minority-carrier lifetime
in the absorber layer of photovoltaic devices.  However, when a measurement
is performed on a device, in addition to carrier lifetime, the TRPL signal
is affected by multiple factors including drift, diffusion and interface
recombination.  Deconvolution of these factors and interpretation of
results is often difficult.Numerical simulations are used to analyze
carrier dynamics after a sample is illuminated with a short light pulse.
 Simulations can determine how material parameters such as doping and
defect density at the interface and bulk, as well as experimental
conditions such as wavelength, illumination intensity and spatial
distribution of photo-generated carriers affect the measured result.A new
formalism that enables greater insight into which factors dominate the TRPL
decay dynamics was developed.  By breaking down the carrier dynamics into
drift, diffusion, and recombination terms this formalism can point which
physical factors dominate the decay dynamics under various conditions and
at different times during the decay. Using this mechanism, it was found
that in a typical CdTe device under typical experimental conditions used in
our laboratories, the faster part of the decay is dominated by drift and
diffusion of carriers, while the slower part is dominated by carrier
recombination.

Bio
Dr. Ana Kanevce received a Ph.D in Physics at Colorado State University
doing characterization and modeling on thin-film solar cells. Since 2007
she has been a member of the Electro-Optical Characterization Group at the
National Renewable Energy Laboratory.  Her research is concentrated on
different  PV technologies, including silicon heterojunction solar cells,
multijunction solar cells based on III-V materials, and thin-film
polycrystalline solar cells with Cu(In,Ga)Se2, Cu2(Zn,Sn)Se4 and CdTe
absorbers.

Regards,

Xufeng
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