Title
Impact of molecular weight on charge carrier dissociation in solar cells from a polyfluorene derivative
Author
Moet, D.J.D.
Lenes, M.
Kotlarski, J.D.
Veenstra, S.C.
Sweelssen, J.
Koetse, M.M.
de Boer, B.
Blom, P.W.M.
TNO Industrie en Techniek
Publication year
2009
Abstract
The effect of the molecular weight of poly[9,9-didecanefluorene-alt-(bis-thienylene) benzothiadiazole] (PF10TBT) on the photovoltaic performance of fullerene-based bulk heterojunction solar cells is investigated. An increase in molecular weight of two orders of magnitude results in a 30% increase of the short-circuit current and a rise of the fill factor from 0.45 to 0.63. Electron and hole transport are found to be virtually unaffected by changing molecular weight, which means that space-charge effects do not play a role in low molecular weight devices. Using optical modeling and numerical device simulations, we demonstrate that at low molecular weight the efficiency is mainly limited by a short lifetime of bound electron-hole pairs. This short lifetime prohibits efficient dissociation and is attributed to a deficiency in phase separation for low molecular weights. © 2009 Elsevier B.V. All rights reserved.
Subject
High Tech Systems & Materials
Electronics
Industrial Innovation
Dissociation
Molecular weight
Polyfluorene
Polymer
Solar cells
Benzothiadiazoles
Bound electrons
Bulk heterojunction solar cells
Charge carrier dissociation
Efficient dissociation
Fill factor
Hole transports
In-phase
Low molecular weight
Numerical device simulation
Optical modeling
Orders of magnitude
Photovoltaic performance
Polyfluorene
Polyfluorene derivative
Short-circuit currents
Space charge effects
Cell membranes
Dissociation
Fullerenes
Heterojunctions
Phase separation
Photovoltaic cells
Solar cells
Solar power generation
Switching circuits
Weighing
Molecular weight
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http://resolver.tudelft.nl/uuid:d64f4a5f-856e-4561-9448-e8f771c05f0a
DOI
https://doi.org/10.1016/j.orgel.2009.07.002
TNO identifier
461637
ISSN
1566-1199
Source
Organic Electronics: physics, materials, applications, 10 (7), 1275-1281
Document type
article