Role of electron-hole pair formation in organic magnetoresistance

Sayani Majumdar*, Himadri S. Majumdar, Harri Aarnio, Dirk Vanderzande, Reino Laiho, Ronald Österbacka

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

57 Citations (Scopus)


Magnetoelectrical measurements were performed on diodes and bulk heterojunction solar cell blends (BHSCs) to clarify the role of formation of Coulombically bound electron-hole (e-h) pairs on the magnetoresistance (MR) response in organic thin-film devices. BHSCs are suitable model systems because they effectively quench excitons but the probability of forming e-h pairs in them can be tuned over orders of magnitude by the choice of material and solvent in the blend. We have systematically varied the e-h recombination coefficients, which are directly proportional to the probability for the charge carriers to meet in space, and found that a reduced probability of electrons and holes meeting in space lead to the disappearance of the MR. Our results clearly show that MR is a direct consequence of the e-h pair formation. We also found that the MR line shape follows a power-law dependence of B0.5 at higher fields.

Original languageEnglish
Article number201202
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number20
Publication statusPublished - 1 May 2009
MoE publication typeA1 Journal article-refereed


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