Comparing small molecules and polymer for future organic spin-valves

Sayani Majumdar (Corresponding Author), Himadri S. Majumdar, Reino Laiho, R. Osterbacka

Research output: Contribution to journalArticleScientificpeer-review

67 Citations (Scopus)

Abstract

We report spin polarized injection and transport in organic spin-valves made from both organic small molecules and polymers. The devices with the structure La0.67Sr0.33MnO3 (LSMO)/organic spacer/Co showed inverse magnetoresistance and low temperature operation with the vacuum evaporated π-conjugated small molecule 8-hydroxyquinoline aluminium (Alq3) while normal MR and high temperature operation was observed in devices with the π-conjugated polymer poly(3-hexylthiophene). Due to the proximate values of the work functions of LSMO and Co with the highest occupied molecular orbital (HOMO) energy of the polymers, spin polarized carrier injection is much more efficient in the polymeric spin-valves compared to the organic spin-valves with Alq3 where carrier injection is hindered due to greater barrier height. Efficient spin transport is also observed in polymeric spin-valves and can be attributed to longer conjugation in the polymeric chains compared to the small molecules.
Original languageEnglish
Pages (from-to)169-171
JournalJournal of Alloys and Compounds
Volume432
Issue number1-2
DOIs
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed

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Polymers
Molecules
Low temperature operations
Oxyquinoline
High temperature operations
Conjugated polymers
Molecular orbitals
Magnetoresistance
Aluminum
Vacuum
poly(3-hexylthiophene)

Cite this

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title = "Comparing small molecules and polymer for future organic spin-valves",
abstract = "We report spin polarized injection and transport in organic spin-valves made from both organic small molecules and polymers. The devices with the structure La0.67Sr0.33MnO3 (LSMO)/organic spacer/Co showed inverse magnetoresistance and low temperature operation with the vacuum evaporated π-conjugated small molecule 8-hydroxyquinoline aluminium (Alq3) while normal MR and high temperature operation was observed in devices with the π-conjugated polymer poly(3-hexylthiophene). Due to the proximate values of the work functions of LSMO and Co with the highest occupied molecular orbital (HOMO) energy of the polymers, spin polarized carrier injection is much more efficient in the polymeric spin-valves compared to the organic spin-valves with Alq3 where carrier injection is hindered due to greater barrier height. Efficient spin transport is also observed in polymeric spin-valves and can be attributed to longer conjugation in the polymeric chains compared to the small molecules.",
author = "Sayani Majumdar and Majumdar, {Himadri S.} and Reino Laiho and R. Osterbacka",
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Comparing small molecules and polymer for future organic spin-valves. / Majumdar, Sayani (Corresponding Author); Majumdar, Himadri S.; Laiho, Reino; Osterbacka, R.

In: Journal of Alloys and Compounds, Vol. 432, No. 1-2, 2006, p. 169-171.

Research output: Contribution to journalArticleScientificpeer-review

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T1 - Comparing small molecules and polymer for future organic spin-valves

AU - Majumdar, Sayani

AU - Majumdar, Himadri S.

AU - Laiho, Reino

AU - Osterbacka, R.

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AB - We report spin polarized injection and transport in organic spin-valves made from both organic small molecules and polymers. The devices with the structure La0.67Sr0.33MnO3 (LSMO)/organic spacer/Co showed inverse magnetoresistance and low temperature operation with the vacuum evaporated π-conjugated small molecule 8-hydroxyquinoline aluminium (Alq3) while normal MR and high temperature operation was observed in devices with the π-conjugated polymer poly(3-hexylthiophene). Due to the proximate values of the work functions of LSMO and Co with the highest occupied molecular orbital (HOMO) energy of the polymers, spin polarized carrier injection is much more efficient in the polymeric spin-valves compared to the organic spin-valves with Alq3 where carrier injection is hindered due to greater barrier height. Efficient spin transport is also observed in polymeric spin-valves and can be attributed to longer conjugation in the polymeric chains compared to the small molecules.

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