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Magnetic Field Effect in -Conjugated Polymer Films Zeev Valy Vardeny, University of Utah, DMR 1104495.
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Magnetic Field Effect in -Conjugated Polymer FilmsZeev Valy Vardeny, University of Utah, DMR 1104495 The magnetic field effect (MFE) in OLEDs such as magneto-conductance has been intensively explored in the last few years. In a recent paper (Phys. Rev. B 85, 245437 (2012)) we demonstrated MFE of two excited state spectroscopies in films of a prototype -conjugated polymer, namely a soluble derivative of poly(phenylene-vinylene) [MEH-PPV];these are magneto-photoinduced absorption (MPA) and M-photoluminescence (MPL).Being spectroscopic in nature, MPA and MPL are determined by the photoexcitation spin density, and thus unravel the occurrence of a myriad of spin-mixing processes in organic semiconductors,including hyperfine interaction in polaron-pairs, spin-sublevel mixing in triplet excitons, triplet-triplet annihilation, and triplet-singlet collision. By studying MPA spectra of various MEH-PPV film forms we showed in our paper that this novel spin-related spectroscopy is indeed an important experimental tool in the young field of Organic Spintronics. The MPA spectroscopy. (a) Schematic of PA and MPA showing the excitation and field (B-) dependent PA(B). (b) The PA and MPA (PA) spectra of MEH-PPV showing polaron (P1 and P2) PA bands.
Magnetic Field Effect in -Conjugated Polymer Films Zeev Valy Vardeny, University of Utah, DMR 1104495 This work has involved three graduate students (one female (Golda) and two males (Bhoj, Ye), and a research associate from Vitenam (Tho). We have also collaborated with a visiting professor from Technion (Dr. Ehrenfreund); our partner in a bi-national science foundation program. A symposium organized by the PI, which highlighted the spin physics in organics took place in March APS meeting in Dallas (3/2011). A public lecture on organic solar cells enhanced by spin ½ radicals was given by the PI in January 2012; and a colloquium on Organic Spintronics was given by the PI at the Technion (March 2012). A patent disclosure on spin-OLED was submitted (July 2012). The research group of Z. V. Vardeny (bottom line, 2nd from left) at the University of Utah in Salt Lake City. The co-PI, T.D. Nguyen is also present (bottom line, 2nd from right). The number of female graduate students (40%) well exceeds that of the US national average; also there are students from seven different nationalities.