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The Photoconversion Mechanism of Excitonic Solar Cells

Published online by Cambridge University Press:  31 January 2011

Brian A. Gregg
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Abstract

Excitonic solar cells (XSCs) function by a mechanism that is different than that of conventional solar cells.They have different limitations on their open circuit photovoltages, and their behavior cannot be interpreted as if they were conventional p–n heterojunctions. Exciton dissociation at the heterojunction produces electrons on one side of the interface already separated from the holes produced on the other side of the interface. This creates a powerful photoinduced interfacial chemical potential energy gradient that drives the photovoltaic effect, even in the absence of a built-in electrical potential. The maximum thermodynamic efficiency achievable in an XSC is shown to be identical to that of a conventional solar cell, with the substitution of the optical bandgap in the XSC for the electronic bandgap in the conventional cell. This article briefly reviews the photovoltaic mechanism of XSCs, the limitations on their photovoltage, and their maximum achievable efficiency.

Keywords

efficiency limitationsexcitonic mechanismorganic solar cells.
Type
Research Article
Information
MRS Bulletin , Volume 30 , Issue 1: Technical Theme: Organic–Based Photovoltaics , January 2005 , pp. 20 - 22
Copyright
Copyright © Materials Research Society 2005

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