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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/2422

Title: Effect of temperature and illumination on the electrical characteristics of polymer-fullerene bulk-heterojunction solar cells
Authors: Riedel, I
Parisi, J
Dyakonov, V
Hummelen, JC
LUTSEN, Laurence
Issue Date: 2004
Citation: ADVANCED FUNCTIONAL MATERIALS, 14(1). p. 38-44
Abstract: The current-voltage characteristics of ITO/PEDOT:PSS/OC1C10-PPV:PCBM/Al solar cells were measured in the temperature range 125-320 K under variable illumination, between 0.03 and 100 mW cm(-2) (white light), with the aim of determining the efficiency-limiting mechanism(s) in these devices, and the temperature and/or illumination range(s) in which these devices demonstrate optimal performance. (ITO: indium tin oxide; PEDOT:PSS: poly(styrene sulfonate)-doped poly(ethylene dioxythiophene); OC1C10-PPV: poly[2-methoxy-5-(3,7-dimethyl octyloxy)-1,4-phenylene vinylene]; PCBM: phenyl-C-61 butyric acid methyl ester.) The short-circuit current density and the fill factor grow monotonically with temperature until 320 K. This is indicative of a thermally activated transport of photogenerated charge carriers, influenced by recombination with shallow traps. A gradual increase of the open-circuit voltage to 0.91 V was observed upon cooling the devices down to 125 K. This fits the picture in which the open-circuit voltage is not limited by the work-function difference of electrode materials used. The overall effect of temperature on solar-cell parameters results in a positive temperature coefficient of the power conversion efficiency, which is 1.9% at T = 320 K and 100 mW cm(-2) (2.5% at 0.7 mW cm(-2)). The almost-linear variation of the short-circuit current density with light intensity confirms that the internal recombination losses are predominantly of monomolecular type under short-circuit conditions. We present evidence that the efficiency of this type of solar cell is limited by a light-dependent shunt resistance. Furthermore, the electronic transport properties of the absorber materials, e.g., low effective charge-carrier mobility with a strong temperature dependence, limit the photogenerated current due to a high series resistance, therefore the active layer thickness must be kept low, which results in low absorption for this particular composite absorber.
Notes: Univ Oldenburg, Fac 5, Lab Energy & Semicond Res, D-26129 Oldenburg, Germany. Limburgs Univ Ctr, Inst Mat Res, B-3590 Diepenbeek, Belgium. IMEC, IMOMEC Div, B-3590 Diepenbeek, Belgium. Univ Groningen, Mol Elect, MCS Plus, NL-9747 AG Groningen, Netherlands.Riedel, I, Univ Oldenburg, Fac 5, Lab Energy & Semicond Res, Carl Von Ossietzky Str 9-11, D-26129 Oldenburg, Germany.dyakonov@uni-oldenburg.de
URI: http://hdl.handle.net/1942/2422
DOI: 10.1002/adfm.200304399
ISI #: 000188857000006
ISSN: 1616-301X
Category: A1
Type: Journal Contribution
Validation: ecoom, 2005
Appears in Collections: Research publications

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