The role of space charge effects on the competition between recombination and extraction in solar cells with low-mobility photoactive layers

Stolterfoht, Martin, Armin, Ardalan, Philippa, Bronson, and Neher, Dieter (2016) The role of space charge effects on the competition between recombination and extraction in solar cells with low-mobility photoactive layers. Journal of Physical Chemistry Letters, 7. pp. 4716-4721.

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Abstract

The competition between charge extraction and nongeminate recombination critically determines the current−voltage characteristics of organic solar cells (OSCs) and their fill factor. As a measure of this competition, several figures of merit (FOMs) have been put forward; however, the impact of space charge effects has been either neglected, or not specifically addressed. Here we revisit recently reported FOMs and discuss the role of space charge effects on the interplay between recombination and extraction. We find that space charge effects are the primary cause for the onset of recombination in so-called non-Langevin systems, which also depends on the slower carrier mobility and recombination coefficient. The conclusions are supported with numerical calculations and experimental results of 25 different donor/acceptor OSCs with different charge transport parameters, active layer thicknesses or composition ratios. The findings represent a conclusive understanding of bimolecular recombination for drift dominated photocurrents and allow one to minimize these losses for given device parameters.

Item ID: 46302
Item Type: Article (Refereed Research - C1)
ISSN: 1948-7185
Funders: German Ministry of Science and Education (GMSE)
Projects and Grants: GMSE FKZ 19 13N13719
Date Deposited: 10 Nov 2016 23:47
FoR Codes: 09 ENGINEERING > 0906 Electrical and Electronic Engineering > 090605 Photodetectors, Optical Sensors and Solar Cells @ 100%
SEO Codes: 85 ENERGY > 8505 Renewable Energy > 850504 Solar-Photovoltaic Energy @ 50%
97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 50%
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