Charge transfer dynamics in polymer-fullerene blends for efficient solar cells
article
Blends of poly(3-hexylthiophene) (P3HT) and the bis-adduct of [6,61-pheuyl-C\61-butyric acid methyl ester (bisPCBM) show enhanced performances in bulk-heterojunction solar cells compared to P3HT:PCBM thin films due to their higher open-circuit voltage. However, it is not clear whether the decrease of the shortcircuit current observed in P3HT-bisPCBM blends originates from the 100 mV reduction of the offset between the lowest unoccupied molecular orbitals of the donor and the acceptor or from, a change in the morphology. The analysis of the photoluminescence dynamics of the various bulk heterojunctions provides information on the dependence of the electron transfer process on their microstructure. We find that in solution, where the donor-acceptor distribution is homogeneous, the photoluminescence dynamics is the same for the bis- and PCBM-based blends, while in thin films the first shows a slower dynamics than the second. This result indicates that the reduction of the LUMO offset of ∼100 meV does not influence the electron transfer efficiency but that the diversity between the photoluminescence dynamics in thin films should be ascribed to the different microstructure of the bulk heterojunctions fabricated with the two acceptors. © 2009 American Chemical Society.
Topics
Bis-adductsBulk heterojunctionButyric acidsCharge-transfer dynamicsDonor-acceptorsElectron transfer processElectron-transfer efficiencyEnhanced performanceLowest unoccupied molecular orbitalMethyl estersPoly-3-hexylthiophenePolymer-fullereneCharge transferChemical bondsDynamicsElectron transitionsEstersFatty acidsIon exchangeMicrostructureMolecular orbitalsOpen circuit voltagePhotoluminescencePolymer blendsSolar cellsThin filmsHeterojunctions
TNO Identifier
461603
ISSN
15206106
Source
Journal of Physical Chemistry B, 113(52), pp. 16513-16517.
Pages
16513-16517
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