Role of electron-hole pair formation in organic magnetoresistance

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

Research output: Contribution to journalArticleScientificpeer-review

55 Citations (Scopus)

Abstract

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
Volume79
Issue number20
DOIs
Publication statusPublished - 2009
MoE publication typeA1 Journal article-refereed

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