Hysteretic electroluminescence in organic light-emitting diodes for spin injection

Salis, G.; Alvarado, S. F.; Tschudy, M.; Brunschwiler, Thomas; Allenspach, R.

doi:10.1103/physrevb.70.085203

Cited by 73 publications

(57 citation statements)

References 16 publications

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“…Recently there has been a growing interest in spin [4,5,6] and magnetic field effects [7,8,9,10,11,12,13,14] in these materials. During the study of sandwich devices made from the π-conjugated polymer polyfluorene (PFO) we recently discovered a large and intriguing magnetoresistive (MR) effect, which we dubbed organic magnetoresitance (OMAR).…”

Section: Introductionmentioning

confidence: 99%

Large magnetoresistance in nonmagneticπ-conjugated semiconductor thin film devices

et al. 2005

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Following the recent discovery of large magnetoresistance at room temperature in polyfluorence sandwich devices, we have performed a comprehensive magnetoresistance study on a set of organic semiconductor sandwich devices made from different pi-conjugated polymers and small molecules. The measurements were performed at different temperatures, ranging from 10K to 300K, and at magnetic fields, B < 100mT . We observed large negative or positive magnetoresistance (up to 10% at 300K and 10mT) depending on material and device operating conditions. We compare the results obtained in devices made from different materials with the goal of providing a comprehensive picture of the experimental data. We discuss our results in the framework of known magnetoresistance mechanisms and find that none of the existing models can explain our results.

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Section: Introductionmentioning

confidence: 99%

Large magnetoresistance in nonmagneticπ-conjugated semiconductor thin film devices

et al. 2005

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“…Organic semiconductors can be divided into fluorescent and phosphorescent types based on singlet and triplet emission. It has been experimentally found that fluorescent organic semiconductors can show magnetic responses in electrical current [1][2][3] to externally applied magnetic field (<100 mT), leading to magnetocurrent (MC) with nonmagnetic electrodes. However, phosphorescent organic semiconductors always exhibit negligible MC due to strong spin-orbital coupling (SOC).…”

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confidence: 99%

“…The observed MC clearly suggests that dispersing Ir(ppy) 3 molecules into an inert polymer matrix can lead to a reduction on the SOC of heavymetal complex molecules. It should be noted that the Ir(ppy) 3 molecules have a strong orbital magnetic field 31 generated by orbital current due to large atomic number of Ir. This strong orbital magnetic field can interact with p electron spins not only within a single molecule but also between adjacent molecules, generating both intra-molecular and inter-molecular SOC, as schematically shown in Fig.…”

mentioning

confidence: 99%

“…The iridium heavy-metal complex molecule: tris(2-phenylpyridine) iridium (Ir(ppy) 3 ), and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT) were purchased from America Dye Source, Inc., and H. C. Starck, respectively, for experimental studies. The poly (methyl methacrylate) (PMMA) and polystyrene (PS), purchased from SigmaAldrich Co., were used as inert polymer matrices with different dielectric constants to host heavy-metal complex Ir(ppy) 3 molecules for the modification of inter-molecular SOC.…”

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confidence: 99%

“…The poly (methyl methacrylate) (PMMA) and polystyrene (PS), purchased from SigmaAldrich Co., were used as inert polymer matrices with different dielectric constants to host heavy-metal complex Ir(ppy) 3 molecules for the modification of inter-molecular SOC. The organic light-emitting diodes were fabricated with indium tin oxide (ITO) with 30 nm PEDOT on top and aluminum (Al) electrodes.…”

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confidence: 99%

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Changing inter-molecular spin-orbital coupling for generating magnetic field effects in phosphorescent organic semiconductors

Yan

Shao

Graeff

et al. 2012

Applied Physics Letters

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Phosphorescent organic semiconductors normally show negligible magnetic field effects in electronic and optic responses. These phenomena have been generally attributed to strong spin-orbital coupling which can dominate internal spin-dephasing process as compared with applied magnetic field. This paper reports both positive and negative magnetocurrents from phosphorescent organic semiconductors through dissociation and charge-reaction channels when the intermolecular spin-orbital coupling is changed based on materials mixing. Our experimental results indicate that inter-molecular spin-orbital coupling is essentially responsible for the generation of magnetic field effects in phosphorescent organic semiconductors.

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Organic Spin Valves: A Review

Devkota

Geng

Subedi

et al. 2016

Adv Funct Materials

106

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accelerated impressively and advanced to a range of materials and a number of techniques to verify the successful injection and transport of the SP carriers. [ 1,2,10,11 ] The effect has been realized in a variety of materials combinations such as FM fi lms, FM/anti-FM coupled layers, or FM semiconductors as the injection/detection electrodes and the metals, superconductors, inorganic semiconductors, organic semiconductors, and insulators including ferroelectric and topological insulators as the spacers. [ 1,2,[12][13][14][15][16][17][18] The GMR effect was extensively studied using non-magnetic metallic interlayer and its applications such as electric switching, magnetic recording, and sensors were suggested and employed. [ 1,2,16 ] However, all-metallic spintronic devices imposed restrictions in applications as they are characterized by short spin relaxation time (≈picosecond) and are not suitable for coherent spin manipulation. [ 1,2,19 ] To overcome these limitations, the spintronics community caught its attention towards hybrid devices with semiconductors (SCs) sandwiched in between the FM layers and continued advancing to a range of semiconducting materials. [ 2,14,[20][21][22] The organic semiconductors (OSCs) are among the youngest members of the spacer materials and were fi rst tested in the spintronic devices only about a decade ago. Nevertheless, OSC devices have been of continuously advancing research topics over the past three decades for their rich physics, fl exible chemi stry, cost effi ciency, and potential applications in new generations of electronic devices including organic light emitting diodes (OLEDs), [23][24][25] organic solar cells, [ 26,27 ] and organic fi eld effect transistor. [ 28,29 ] In fact, OLEDs have already revolutionized the modern display industry and spin-dependent devices such as organic spin valves (OSVs), OLED-based magnetic sensors, and spin-OLEDs are under intensive study to achieve their new avenues. [30][31][32] This increasing interest on organic electronics is for their several distinctions over inorganic counterparts. [19][20][21]33,34 ] Electronically, the band theory explains the electric transport in inorganic SCs while charge hopping is the main transport mechanism in the OSCs with much smaller carrier mobility. This is a favorable condition for large electron-hole pair recombination without the need of using a p-n junction structure. [23][24][25] Spintronically, the inorganic SCs contain heavy atoms giving rise to a large spin-orbit coupling (SOC), which is a response of the electron spin degree of freedom to its orbital environment. The strength of the SOC in solids depends upon the nature of orbital wave functions of electrons and the materials structure. [ 35 ] In case of hydrogenic wave-function-like electrons (s-orbital electrons), it is Organic spintronics is an emerging and potential platform for future electronic devices. Signifi cant progress has been made in understanding the spin injection, manipulation, and detection in organic spin valves in the p...

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Hysteretic electroluminescence in organic light-emitting diodes for spin injection

Cited by 73 publications

References 16 publications

Large magnetoresistance in nonmagneticπ-conjugated semiconductor thin film devices

Large magnetoresistance in nonmagneticπ-conjugated semiconductor thin film devices

Changing inter-molecular spin-orbital coupling for generating magnetic field effects in phosphorescent organic semiconductors

Organic Spin Valves: A Review

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