AVS 59th Annual International Symposium and Exhibition
    Energy Frontiers Focus Topic Monday Sessions
       Session EN+NS-MoM

Paper EN+NS-MoM11
Intermediate Band Upconversion for Low-Cost, Solution Processed Photovoltaics

Monday, October 29, 2012, 11:40 am, Room 15

Session: Nanostructured Solar Cells
Presenter: J. Lewis, RTI International
Authors: J. Lewis, RTI International
E.J.D. Klem, RTI International
C.W. Gregory, RTI International
G.B. Cunningham, RTI International
S. Hall, RTI International
D.S. Temple, RTI International
Correspondent: Click to Email
PV devices based on disordered semiconductors such as polymers, organic small molecules, and colloidal quantum dots have seen gradually improving performance in recent years, but are likely to be limited to efficiencies in the range of 10–15%. To increase efficiency further would require the use of tandem cells, which adds complexity and cost. Alternatively one can pursue devices such as intermediate band solar photovoltaics (IBPV) that can exceed the Shockley-Queisser efficiency limit. In an IBPV device mid-gap states are incorporated into a wider band-gap host, allowing infrared photons to contribute to the photocurrent of the device via sequential absorption of two photons. Ideally this occurs without compromising the open circuit voltage. We will present the first example of an IBPV solar cell using solution processed, low-cost disordered materials. We show that the nature of the defect states in Pb-salt quantum dots is uniquely suited to efficient upconversion at optical power densities that are relevant for unconcentrated solar illumination. This demonstration provides a path for a step-change in the efficiency of low-cost PV.