APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016;
Baltimore, Maryland
Session R32: Plasmonics and Beyond II: Ultrafast Dynamics
8:00 AM–11:00 AM,
Thursday, March 17, 2016
Room: 332
Sponsoring
Unit:
DCP
Chair: Teri Odom, Northwestern University
Abstract ID: BAPS.2016.MAR.R32.8
Abstract: R32.00008 : Solar upconversion with plasmonic hot carriers
9:48 AM–10:24 AM
Preview Abstract
Abstract
Author:
Jennifer A. Dionne
(Stanford University)
Upconversion of sub-bandgap photons is a promising approach to exceed the
Shockley-Queisser limit in solar technologies. Placed behind a solar cell,
upconverting materials convert lower-energy photons transmitted through the
cell to higher-energy above-bandgap photons that can then be absorbed by the
cell and contribute to photocurrent. Because the upconverter is electrically
isolated from the active cell, it need not be current-matched to the cell,
nor will it add mid-gap recombination pathways. Calculations have indicated
that single-junction cell efficiencies can exceed 44{\%} upon addition of an
upconverter -- a significant improvement over the maximum cell efficiency of
30{\%} without an upconverter. However, due to the low quantum efficiencies
and narrow absorption bandwidths of existing upconverters, such significant
cell improvements have yet to be observed experimentally.~ \newline
\newline
In this presentation, we will describe an entirely new solar upconverting
scheme based on hot-carrier injection from a plasmonic absorber to an
adjacent semiconductor. The plasmonic system both induces upconversion based
on injection of hot-electrons and hot-holes and also enhances light-matter
interactions. Low-energy photons incident on a plasmonic particle generate
hot electrons and hot holes, which are injected into a semiconducting
quantum well and subsequently radiatively recombine. Importantly, the
bandgap of the quantum well can be higher than the energy of the incident
photon, enabling emission of a higher-energy photon than that absorbed.
First, we present analytic calculations showing that efficiencies as high as
25{\%} are possible, significantly higher than existing solid-state
upconverters, which are only 2-5{\%} efficient. We also describe how further
improvements in the efficiency are possible by employing materials and
geometries that allow for more efficient carrier injection. Then, we
describe experiments on InGaN/GaN quantum wells decorated with Au disks. On
their own, the InGaN/GaN quantum wells do not upconvert. With the addition
of the gold disks, strong upconversion is observed. We show how this new
upconversion scheme offers spectral tunability across visible and
near-infrared frequencies, does not require coherent illumination, is a
linear process, and can be broadband.\\
\\Contributing authors include Guru Naik and Alex Welch, Stanford University
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2016.MAR.R32.8