title: Electron Spin Relaxation of Hole and Electron Polarons in π-Conjugated Porphyrin Arrays: Spintronic Implications.
abstract: Electron spin resonance (ESR) spectroscopic line shape analysis and continuous-wave (CW) progressive microwave power saturation experiments are used to probe the relaxation behavior and the relaxation times of charged excitations (hole and electron polarons) in meso-to-meso ethyne-bridged (porphinato)zinc(II) oligomers (PZnn compounds), which can serve as models for the relevant states generated upon spin injection. The observed ESR line shapes for the PZnn hole polaron ([PZnn](+•)) and electron polaron ([PZnn](-•)) states evolve from Gaussian to more Lorentzian as the oligomer length increases from 1.9 to 7.5 nm, with solution-phase [PZnn](+•) and [PZnn](-•) spin-spin (T2) and spin-lattice (T1) relaxation times at 298 K ranging, respectively, from 40 to 230 ns and 0.2 to 2.3 μs. Notably, these very long relaxation times are preserved in thick films of these species. Because the magnitudes of spin-spin and spin-lattice relaxation times are vital metrics for spin dephasing in quantum computing or for spin-polarized transport in magnetoresistive structures, these results, coupled with the established wire-like transport behavior across metal-dithiol-PZnn-metal junctions, present meso-to-meso ethyne-bridged multiporphyrin systems as leading candidates for ambient-temperature organic spintronic applications.
authors.affiliation: †Department of Chemistry, French Family Science Center, Duke University, 124 Science Drive, Durham, North Carolina 27708-0346, United States.
authors.forename: Jeff
authors.initials: J
authors.lastname: Rawson
authors.affiliation: ‡Department of Physics, Saint Joseph's University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Angiolillo
authors.affiliation: §Department of Chemistry, The University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Frail
authors.affiliation: ‡Department of Physics, Saint Joseph's University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States.
authors.forename: Isabella
authors.initials: I
authors.lastname: Goodenough
authors.affiliation: †Department of Chemistry, French Family Science Center, Duke University, 124 Science Drive, Durham, North Carolina 27708-0346, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Therien