MATERIALS SCIENCE COLLOQUIUM

SPEAKER: Dr. Alex Martinson
Argonne National Laboratory
Materials Science Division
TITLE: "New Designs for Affordable Photovoltaics: Materials, Interfaces, and Economics"
DATE: Thursday, April 21, 2011
TIME: 11:00 a.m.
PLACE: Building 212 / A-157
HOST: Michael Pellin

Refreshments will be served at 10:45 a.m.

ABSTRACT: Identifying sufficient supplies of clean energy for the future is one of society's most daunting challenges. The direct conversion of solar energy to electricity is one of our most enticing solutions. I will briefly discuss the state of solar energy conversion before describing some unconventional designs in thin film photovoltics (TFPV) and dye-sensitized solar cells (DSSCs).
The most desirable TFPVs would utilize inexpensive materials without sacrificing efficiency. However, TFPVs commercialized to date require rigorous materials purification, employ rare and costly elements, or require high temperature processing – all of which significantly drive up the levelized cost of energy (LCOE). Surmounting the incongruity between light absorption and charge collection in inexpensive materials may be accomplished by decoupling light absorption and carrier extraction into orthogonal spatial dimensions. An interdigitated device design made possible through advances in atomic layer deposition (ALD) will be illustrated.
DSSCs differ from other photovoltaics in that they rely on a large area nanoparticle network to achieve sufficient absorption of visible light. Although highly successful to date, this approach limits the opportunities to reduce the potential loss inherent in conventional DSSC design. I will show a resonantly coupled cavity scheme that realizes a 30-fold increase in monochromatic incident-photon-to-current efficiency compared to the planar control. On resonance we observe record open-circuit voltages that approach the theoretical limit set by the traditional Ru-dye and iodide-based electrolyte.