Observation of ferromagnetic ordering in conjugated polymers exhibiting OMAR effect

Sayani Majumdar, Jan-Olof Lill, Johan Rajander, Himadri Majumdar

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)


We report observation of ferromagnetic (FM) ordering in π-conjugated polymeric semiconductors, namely regio-regular poly (3-hexyl thiophene) (RRP3HT) and 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene (PCBM), in the temperature range of 5–300 K. Diodes made from these polymers exhibit sizable magnetoresistance (known commonly as OMAR). However, upon blending these two materials, the FM ordering is suppressed by a huge paramagnetic (PM) signal. In the diodes with RRP3HT:PCBM blend showing PM response, OMAR decreases substantially. Particle induced X-ray emission spectroscopy indicate presence of dilute magnetic impurities as residues from the synthesis process in the individual polymers. However the impurity signal is unable to explain the temperature dependence of magnetization in these materials and the observed paramagnetism of the RRP3HT:PCBM blend. We propose a hypothesis for the origin of the FM nature of these polymers based on ours and previously reported experimental observations and pointed out that the reported organic magnetoresistance might have a close correlation with the ferromagnetic interaction in these polymers.
Original languageEnglish
Pages (from-to)66-72
JournalOrganic electronics
Publication statusPublished - 2015
MoE publication typeA1 Journal article-refereed


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