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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/18852

Title: Effect of molecular weight on morphology and photovoltaic properties in P3HT:PCBM solar cells
Authors: SPOLTORE, Donato
BERTHO, Sabine
Van den Brande, Niko
Defour, Maxime
Van Mele, Bruno
De Sio, Antonietta
Parisi, Juergen
LUTSEN, Laurence
MAES, Wouter
Issue Date: 2015
Citation: ORGANIC ELECTRONICS, 21, p. 160-170
Abstract: The molecular weight of poly(3-hexylthiophene) is an important factor influencing the photovoltaic properties of bulk heterojunction organic solar cells based on this material. However, since different synthetic processes or repetitive soxhlet extractions - generally applied to obtain the different molecular weight batches under study - result in samples with simultaneously varying regioregularity (RR) and polydispersity index (PDI), it has not been possible yet to find an unambiguous correlation between the molecular weight and the photovoltaic performance. In the present work preparative gel permeation chromatography is introduced as a versatile technique to fractionate the donor polymer and thereby obtain a systematic variation of the number average molecular weight (M-n = 11-91 kg mol (1)) with an almost constant PDI and RR. Polymer crystallinity and conjugation length are evaluated by UV-Vis spectroscopy, rapid heat-cool calorimetry and selected area electron diffraction, and are found to be deeply affected by Mn. This in turn influences the behavior of the charge transfer state energy, measured via Fourier transform photocurrent spectroscopy, and therefore the open-circuit voltage. The short-circuit current is also affected by Mn, but mainly due to a change in absorption coefficient. The apparent recombination order is shown to be linked to the morphology of the polymer: fullerene blend and is determined using transient photovoltage and photocurrent techniques. Finally, a correlation between recombination and fill factor is also suggested. (C) 2015 Elsevier B.V. All rights reserved.
Notes: [Spoltore, Donato; Vangerven, Tim; Piersimoni, Fortunato; Bertho, Sabine; Manca, Jean V.] Hasselt Univ, Inst Mat Res IMO, Mat Phys, B-3590 Diepenbeek, Belgium. [Verstappen, Pieter; Vanderzande, Dirk; Maes, Wouter] Hasselt Univ, Inst Mat Res IMO, Design & Synth Organ Semicond, B-3590 Diepenbeek, Belgium. [Verstappen, Pieter; Lutsen, Laurence; Vanderzande, Dirk; Maes, Wouter; Manca, Jean V.] IMEC, Div IMOMEC, B-3590 Diepenbeek, Belgium. [Vandewal, Koen] Tech Univ Dresden, Inst Angew Photophys, D-01069 Dresden, Germany. [Van den Brande, Niko; Defour, Maxime; Van Mele, Bruno] Vrije Univ Brussel, Fac Engn Sci, Dept Phys Chem & Polymer Sci, B-1050 Brussels, Belgium. [De Sio, Antonietta; Parisi, Juergen] Carl von Ossietzky Univ Oldenburg, Inst Phys, D-26111 Oldenburg, Germany.
URI: http://hdl.handle.net/1942/18852
DOI: 10.1016/j.orgel.2015.02.017
ISI #: 000352499100023
ISSN: 1566-1199
Category: A1
Type: Journal Contribution
Validation: ecoom, 2016
Appears in Collections: Research publications

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