Spontaneous Charge Transfer and Dipole Formation at the Interface Between P3HT and PCBM

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Aarnio, Harri and Sehati, Parisa and Braun, Slawomir and Nyman, Mathias and Jong, Michel P. de and Fahlman, Mats and Österbacka, Ronald (2011) Spontaneous Charge Transfer and Dipole Formation at the Interface Between P3HT and PCBM. Advanced Energy Materials, 1 (5). pp. 792-797. ISSN 1614-6840

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Abstract:In the pursuit of developing new materials for more effi cient bulk-heterojunction solar cells, the blend poly (3-hexylthiophene):[6,6]-phenyl- C 61 -butyric acid methyl ester (P3HT:PCBM) serves as an important model system. The success of the P3HT:PCBM blend comes from effi cient charge generation and transport with low recombination. There is not, however, a good microscopic picture of what causes these, hindering the development of new material systems. In this report UV photoelectron spectroscopy measurements on both regiorandom- (rra) and regioregular- (rr) P3HT are presented, and the results are interpreted using the Integer Charge Transfer model. The results suggest that spontaneous charge transfer from P3HT to PCBM occurs after heat treatment of P3HT:PCBM blends. The resulting formation of an interfacial dipole creates an extra barrier at the interface explaining the reduced (non-)geminate recombination with increased charge generation in heat treated rr-P3HT:PCBM blends. Extensive photoinduced absorption measurements using both above- and below-bandgap excitation light are presented, in good agreement with the suggested dipole formation.
Item Type:Article
Copyright:© 2011 Wiley
Faculty:
Electrical Engineering, Mathematics and Computer Science (EEMCS)
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Link to this item:http://purl.utwente.nl/publications/79321
Official URL:http://dx.doi.org/10.1002/aenm.201100074
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