TY  - JOUR
A1  - Stolterfoht, Martin
A1  - Armin, Ardalan
A1  - Philippa, Bronson
A1  - Neher, Dieter
T1  - The Role of Space Charge Effects on the Competition between Recombination and Extraction in Solar Cells with Low-Mobility Photoactive Layers
JF  - The journal of physical chemistry letters
N2  - 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.
Y1  - 2016
U6  - https://doi.org/10.1021/acs.jpclett.6b02106
SN  - 1948-7185
VL  - 7
SP  - 4716
EP  - 4721
PB  - American Chemical Society
CY  - Washington
ER  -