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Wagner TW, Johnson JC, Reid OG. Trap-Filling Magnetoconductance as an Initialization and Readout Mechanism of Triplet Exciton Spins. J Phys Chem Lett 2022; 13:9895-9902. [PMID: 36256578 DOI: 10.1021/acs.jpclett.2c02710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Photoexcited triplet states are promising candidates for hybrid qubit systems, as they can be used as a controlling gate for nuclear spins. But microwave readout schemes do not generally offer the sensitivity needed to approach the single-molecule limit or the scope to integrate such systems into devices. Here, we demonstrate the possibility of electrical readout of triplet spins at room temperature through a specific mechanism of magnetoconductance (MC) in polycrystalline pentacene. We show that hole-only pentacene devices exhibit a positive photoinduced MC response that is consistent with a trap-filling mechanism. Spin and magnetic-field-dependent quenching of photogenerated triplets by holes quantitatively explains the MC response we observe. These results are distinct in both sign and proposed mechanism compared to previous reports on polyacene materials and provide clear design rules for future spintronic devices based on this spin-sensing mechanism.
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Affiliation(s)
- Taylor W Wagner
- Department of Physics, Colorado School of Mines, Golden, Colorado80401-2550, United States
- National Renewable Energy Laboratory, Golden, Colorado80401, United States
| | - Justin C Johnson
- National Renewable Energy Laboratory, Golden, Colorado80401, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado80309, United States
| | - Obadiah G Reid
- National Renewable Energy Laboratory, Golden, Colorado80401, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado80309, United States
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2
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Kirk ML, Shultz DA, Hewitt P, van der Est A. Excited State Exchange Control of Photoinduced Electron Spin Polarization in Electronic Ground States. J Phys Chem Lett 2022; 13:872-878. [PMID: 35045702 DOI: 10.1021/acs.jpclett.1c03491] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ground-state electron spin polarization (ESP) is generated in radical elaborated (bpy)Pt(CAT-NN) and (bpy)Pt(CAT-p-Me2PhMe2-NN) (bpy = 5,5'-di-tert-butyl-2,2'-bipyridine, CAT = 3-tert-butylcatecholate, p-Ph = para-phenylene, NN = nitronylnitroxide). Photoexcitation produces an exchange-coupled, three-spin, charge-separated doublet 2S1 (S = chromophore excited spin singlet configuration) excited state that rapidly decays to a 2T1 (T = chromophore excited spin triplet configuration) excited state. The SQ-bridge-NN bond torsions affect the magnitude of the excited state exchange interaction (JSQ-NN), which determines the 2T1-4T1 energy gap. Ground state ESP is dependent on the magnitude of JSQ-NN, and we postulate that this results from differences in 2T1 and 4T1 state mixing. Mechanisms that lead to the rapid transfer of the excited state ESP to the ground state are discussed. Although subnanosecond 2T1 state lifetimes are measured optically in solution, the ground state ESP decays very slowly at 20 K and is observable for more than a millisecond.
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Affiliation(s)
- Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
- The Center for High Technology Materials, The University of New Mexico, Albuquerque, New Mexico 87106, United States
| | - David A Shultz
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Patrick Hewitt
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Art van der Est
- Department of Chemistry, Brock University, St. Catharines, Ontario L2S 3A1, Canada
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3
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Kirk ML, Shultz DA, Hewitt P, Stasiw DE, Chen J, van der Est A. Chromophore-radical excited state antiferromagnetic exchange controls the sign of photoinduced ground state spin polarization. Chem Sci 2021; 12:13704-13710. [PMID: 34760154 PMCID: PMC8549796 DOI: 10.1039/d1sc02965g] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/01/2021] [Indexed: 11/21/2022] Open
Abstract
A change in the sign of the ground-state electron spin polarization (ESP) is reported in complexes where an organic radical (nitronylnitroxide, NN) is covalently attached to a donor-acceptor chromophore via two different meta-phenylene bridges in (bpy)Pt(CAT-m-Ph-NN) (mPh-Pt) and (bpy)Pt(CAT-6-Me-m-Ph-NN) (6-Me-mPh-Pt) (bpy = 5,5'-di-tert-butyl-2,2'-bipyridine, CAT = 3-tert-butylcatecholate, m-Ph = meta-phenylene). These molecules represent a new class of chromophores that can be photoexcited with visible light to produce an initial exchange-coupled, 3-spin (bpy˙-, CAT+˙ = semiquinone (SQ), and NN), charge-separated doublet 2S1 (S = chromophore excited spin singlet configuration) excited state. Following excitation, the 2S1 state rapidly decays to the ground state by magnetic exchange-mediated enhanced internal conversion via the 2T1 (T = chromophore excited spin triplet configuration) state. This process generates emissive ground state ESP in 6-Me-mPh-Pt while for mPh-Pt the ESP is absorptive. It is proposed that the emissive polarization in 6-Me-mPh-Pt results from zero-field splitting induced transitions between the chromophoric 2T1 and 4T1 states, whereas predominant spin-orbit induced transitions between 2T1 and low-energy NN-based states give rise to the absorptive polarization observed for mPh-Pt. The difference in the sign of the ESP for these molecules is consistent with a smaller excited state 2T1 - 4T1 gap for 6-Me-mPh-Pt that derives from steric interactions with the 6-methyl group. These steric interactions reduce the excited state pairwise SQ-NN exchange coupling compared to that in mPh-Pt.
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Affiliation(s)
- Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico MSC03 2060, 1 University of New Mexico Albuquerque NM 87131-0001 USA
| | - David A Shultz
- Department of Chemistry, North Carolina State University Raleigh North Carolina 27695-8204 USA
| | - Patrick Hewitt
- Department of Chemistry, North Carolina State University Raleigh North Carolina 27695-8204 USA
| | - Daniel E Stasiw
- Department of Chemistry, North Carolina State University Raleigh North Carolina 27695-8204 USA
| | - Ju Chen
- Department of Chemistry and Chemical Biology, The University of New Mexico MSC03 2060, 1 University of New Mexico Albuquerque NM 87131-0001 USA
| | - Art van der Est
- Department of Chemistry, Brock University St. Catharines Ontario Canada L2S 3A1
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4
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Kirk ML, Shultz DA, Chen J, Hewitt P, Daley D, Paudel S, van der Est A. Metal Ion Control of Photoinduced Electron Spin Polarization in Electronic Ground States. J Am Chem Soc 2021; 143:10519-10523. [PMID: 34251803 DOI: 10.1021/jacs.1c04149] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Both the sign and intensity of photoinduced electron spin polarization (ESP) in the electronic ground state doublet (2S0/D0) of chromophore-radical complexes can be controlled by changing the nature of the metal ion. The complexes consist of an organic radical (nitronyl nitroxide, NN) covalently attached to a donor-acceptor chromophore via a m-phenylene bridge, (bpy)M(CAT-m-Ph-NN) (1) (bpy = 4,4'-di-tert-butyl-2,2'-bipyridine, M = PdII (1-Pd) or PtII (1-Pt), CAT = 3-tert-butylcatecholate, m-Ph = meta-phenylene). In both complexes, photoexcitation with visible light produces an initial exchange-coupled, three-spin (bpy•-, CAT•+ = semiquinone (SQ), and NN•), charge-separated doublet 2S1 (S = chromophore excited spin singlet configuration) excited state that rapidly decays to the ground state via a 2T1 (T = chromophore excited spin triplet configuration) state. This process is not expected to be spin selective, and only very weak emissive ESP is found for 1-Pd. In contrast, strong absorptive ESP is generated in 1-Pt. It is postulated that zero-field-splitting-induced transitions between the chromophoric 2T1 and 4T1 states (1-Pd and 1-Pt) and spin-orbit-induced transitions between 2T1 and NN-based quartet states (1-Pt) account for the differences in polarization.
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Affiliation(s)
- Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, Albuquerque, New Mexico 87131-0001, United States.,The Center for High Technology Materials, The University of New Mexico, Albuquerque, New Mexico 87106, United States
| | - David A Shultz
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Ju Chen
- Department of Chemistry and Chemical Biology, The University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - Patrick Hewitt
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - David Daley
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Sangita Paudel
- Department of Chemistry and Chemical Biology, The University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - Art van der Est
- Department of Chemistry, Brock University, St. Catharines, Ontario, Canada L2S 3A1
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Kandrashkin YE, van der Est A. The triplet mechanism of electron spin polarization in moderately coupled triplet-doublet rigid complexes as a source of the enhanced +1/2 ↔ −1/2 transitions. J Chem Phys 2019; 151:184301. [DOI: 10.1063/1.5127762] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Yuri E. Kandrashkin
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of RAS, Kazan, Russian Federation
| | - Art van der Est
- Department of Chemistry Brock University, St. Catharines, Ontario L2S 3A1, Canada
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6
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Teki Y. Excited‐State Dynamics of Non‐Luminescent and Luminescent π‐Radicals. Chemistry 2019; 26:980-996. [DOI: 10.1002/chem.201903444] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/28/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Yoshio Teki
- Division of Molecular Materials ScienceGraduate School of ScienceOsaka City University 3-3-138 Sugimoto Sumiyoshi-ku Osaka 558-8585 Japan
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7
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Tichnell CR, Daley DR, Stein BW, Shultz DA, Kirk ML, Danilov EO. Wave Function Control of Charge-Separated Excited-State Lifetimes. J Am Chem Soc 2019; 141:3986-3992. [DOI: 10.1021/jacs.8b13011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Christopher R. Tichnell
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - David R. Daley
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Benjamin W. Stein
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - David A. Shultz
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Martin L. Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - Evgeny O. Danilov
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
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8
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Stein BW, Tichnell CR, Chen J, Shultz DA, Kirk ML. Excited State Magnetic Exchange Interactions Enable Large Spin Polarization Effects. J Am Chem Soc 2018; 140:2221-2228. [DOI: 10.1021/jacs.7b11397] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Benjamin W. Stein
- Department
of Chemistry and Chemical Biology, The University of New Mexico, MSC03
2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
- Chemistry
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Christopher R. Tichnell
- Department
of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Ju Chen
- Department
of Chemistry and Chemical Biology, The University of New Mexico, MSC03
2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - David A. Shultz
- Department
of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Martin L. Kirk
- Department
of Chemistry and Chemical Biology, The University of New Mexico, MSC03
2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
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9
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Katayama K, Hirotsu M, Kinoshita I, Teki Y. Synthesis, magnetic properties and dynamic behavior of cobalt complexes with an anthracene-containing dioxolene ligand. Dalton Trans 2014; 43:13384-91. [DOI: 10.1039/c4dt01574f] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Katayama K, Hirotsu M, Kinoshita I, Teki Y. Design, synthesis, magnetic properties of a π-radical ligand with photo-excited high-spin state and its Fe(ii) complex. The first stage of a new strategy for LIESST materials. Dalton Trans 2012; 41:13465-73. [DOI: 10.1039/c2dt31831h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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