scholarly journals A high-spin ground-state donor-acceptor conjugated polymer

2019 ◽  
Vol 5 (5) ◽  
pp. eaav2336 ◽  
Author(s):  
A. E. London ◽  
H. Chen ◽  
M. A. Sabuj ◽  
J. Tropp ◽  
M. Saghayezhian ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
High Spin ◽  
Ground State ◽  
Conjugated Polymer ◽  
Organic Materials ◽  
Energy Gap ◽  
Light Element ◽  
Paramagnetic Resonance ◽  
Practical Applications ◽  
Polymer Semiconductor

Interest in high-spin organic materials is driven by opportunities to enable far-reaching fundamental science and develop technologies that integrate light element spin, magnetic, and quantum functionalities. Although extensively studied, the intrinsic instability of these materials complicates synthesis and precludes an understanding of how fundamental properties associated with the nature of the chemical bond and electron pairing in organic materials systems manifest in practical applications. Here, we demonstrate a conjugated polymer semiconductor, based on alternating cyclopentadithiophene and thiadiazoloquinoxaline units, that is a ground-state triplet in its neutral form. Electron paramagnetic resonance and magnetic susceptibility measurements are consistent with a high-to-low spin energy gap of 9.30 × 10−3 kcal mol−1. The strongly correlated electronic structure, very narrow bandgap, intramolecular ferromagnetic coupling, high electrical conductivity, solution processability, and robust stability open access to a broad variety of technologically relevant applications once thought of as beyond the current scope of organic semiconductors.

scholarly journals High-mobility semiconducting polymers with different spin ground states

2021 ◽  
Author(s):  
Xiao-Xiang Chen ◽  
Jia-Tong Li ◽  
Yu-Hui Fang ◽  
Xue-Qing Wang ◽  
Guangchao Liu ◽  
...  
Keyword(s):  
Solid State ◽  
Organic Semiconductors ◽  
High Spin ◽  
Ground State ◽  
Ground States ◽  
High Mobility ◽  
Building Blocks ◽  
Design Strategy ◽  
Semiconducting Polymers ◽  
Related Phenomenon

Abstract Organic semiconductors with high-spin ground states are fascinating because they could enable fundamental understanding on spin-related phenomenon in light element and provide opportunities for organic magnetic and quantum materials. Although high-spin ground states have been observed in some quinoidal type small molecules or doped organic semiconductors, semiconducting polymers with high-spin at its neutral ground state are rarely reported because of the less of clear design strategy. Here we propose a molecular design strategy to obtain high-mobility semiconducting polymers with different spin ground states. We show that polymer building blocks with small singlet-triplet energy gap (ΔES−T) could enable small ΔES−T gap and increase the diradical character in copolymers. We first demonstrate that the spin density and solid-state interchain interactions in the high-spin polymers are crucial for their ground states. Polymers with a triplet ground state (S = 1) could exhibit doublet (S = 1/2) behavior due to the solid-state interchain spin-spin interactions. Besides, these polymers showed outstanding charge transport properties with high hole/electron mobilities and can be both n- and p-doped with superior conductivities. Our results demonstrate a rational design approach to high-mobility semiconducting polymers with different spin ground states.

scholarly journals Vacancy tuned thermoelectric properties and high spin filtering performance in graphene/silicene heterostructures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zainab Gholami ◽  
Farhad Khoeini
Keyword(s):  
Electric Fields ◽  
High Spin ◽  
High Efficiency ◽  
Practical Applications ◽  
External Electric Fields ◽  
Ferromagnetic Exchange ◽  
High Spin Polarization ◽  
Filtering Effect ◽  
Spin Switching ◽  
Spin Filtering

AbstractThe main contribution of this paper is to study the spin caloritronic effects in defected graphene/silicene nanoribbon (GSNR) junctions. Each step-like GSNR is subjected to the ferromagnetic exchange and local external electric fields, and their responses are determined using the nonequilibrium Green’s function (NEGF) approach. To further study the thermoelectric (TE) properties of the GSNRs, three defect arrangements of divacancies (DVs) are also considered for a larger system, and their responses are re-evaluated. The results demonstrate that the defected GSNRs with the DVs can provide an almost perfect thermal spin filtering effect (SFE), and spin switching. A negative differential thermoelectric resistance (NDTR) effect and high spin polarization efficiency (SPE) larger than 99.99% are obtained. The system with the DV defects can show a large spin-dependent Seebeck coefficient, equal to Ss ⁓ 1.2 mV/K, which is relatively large and acceptable. Appropriate thermal and electronic properties of the GSNRs can also be obtained by tuning up the DV orientation in the device region. Accordingly, the step-like GSNRs can be employed to produce high efficiency spin caloritronic devices with various features in practical applications.

Zur Berechnung der chemischen Verschiebung unter besonderer Berücksichtigung des paramagnetischen Terms / Attempts to the Calculation of the Chemical Shift with Especial Consideration of the Paramagnetic Term

1977 ◽  
Vol 32 (12) ◽  
pp. 1541-1543
Author(s):  
H. Sterk ◽  
J. J. Suschnigg
Keyword(s):  
Chemical Shift ◽  
Excited States ◽  
Ground State ◽  
Energy Gap

Abstract Attempts to the Calculation of the Chemical Shift with Especial Consideration of the Paramagnetic Term The calculation of the paramagnetic term according to the Pople formalism of the chemical shift is expanded. The hitherto constant value of the energy gap between the ground state and the excited states is replaced by the value of the lowest lying excitation. This leads to a remarkably better differentiation of the paramagnetic terms of different compounds. The influence is shown on ethane, ethene and ethine.

Mössbauer, Electron Paramagnetic Resonance, and Theoretical Study of a High-Spin, Four-Coordinate Fe(II) Diketiminate Complex

2008 ◽  
Vol 47 (19) ◽  
pp. 8687-8695 ◽  
Author(s):  
Sebastian A. Stoian ◽  
Jeremy M. Smith ◽  
Patrick L. Holland ◽  
Eckard Münck ◽  
Emile L. Bominaar
Keyword(s):  
Electron Paramagnetic Resonance ◽  
High Spin ◽  
Theoretical Study ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

MO-Theoretical Studies on a Model Complex for Deoxymyoglobin

1998 ◽  
Vol 53 (9) ◽  
pp. 755-765
Author(s):  
Christian Kollma ◽  
Sighart F. Fischer ◽  
Michael C. Böhm
Keyword(s):  
High Spin ◽  
Ground State ◽  
High Spin State ◽  
Open Shell ◽  
Spin States ◽  
Hartree Fock ◽  
Intermediate Spin ◽  
Model Complex ◽  
Out Of Plane ◽  
Overlap Method

AbstractThe origin of the displacement of the Fe atom in deoxymyoglobin with respect to the porphyrin plane in the high-spin state is examined by a qualitative molecular orbital (MO) analysis on the extended Hückel level. We find that attachment of a fifth ligand (imidazole in our model complex) to Fe(II)porphyrin favors the out-of-plane shift due to a strengthening of the bonding interaction between Fe and the nitrogen of the imidazole ligand. This results in a high-spin (5 = 2) ground state with Fe shifted out-of-plane for the five-coordinate complex instead of an intermediate spin ground state (5 = 1) with Fe lying in the plane for four-coordinate Fe(II)porphyrin. The relative energies of the different spin states as a function of the distance between Fe and the porphyrin plane are evaluated using an ROHF (restricted open shell Hartree-Fock) version of an INDO (intermediate neglect of differential overlap) method. We observe a level crossing between high-spin and intermediate spin states whereas the low-spin (5 = 0) state remains always higher in energy.

Paramagnetic resonance in the nickel Tutton salts

1952 ◽  
Vol 213 (1115) ◽  
pp. 459-473 ◽  
Keyword(s):  
Electric Field ◽  
Magnetic Anisotropy ◽  
Ground State ◽  
Absorption Lines ◽  
Crystalline Electric Field ◽  
Paramagnetic Resonance ◽  
Triplet Ground State ◽  
Tutton Salts ◽  
Splitting Factor ◽  
Rhombic Symmetry

The paramagnetic resonance spectra of five nickel Tutton salts have been analyzed at 290° K. The positions and intensities of the absorption lines are adequately explained by a crystalline electric field of rhombic symmetry. The triplet ground state is resolved into three singlets with an overall splitting of the order of 3 cm -1 , and the spectroscopic splitting factor g is found to be 2.25 ± 0.05. A comparison is made between the directly measured values of the magnetic anisotropy, and the values calculated using the resonance results.

scholarly journals On-surface Synthesis of [7]triangulene Quantum Ring via Antidot Engineering

2020 ◽  
Author(s):  
Jie Su ◽  
Wei Fan ◽  
Pingo Mutombo ◽  
Xinnan Peng ◽  
Shaotang Song ◽  
...  
Keyword(s):  
High Spin ◽  
Ground State ◽  
Density Functional ◽  
Magnetic Ordering ◽  
Open Shell ◽  
Scanning Tunneling ◽  
Quantum Ring ◽  
Tunneling Microscopy ◽  
Entire Family ◽  
Spin Polarized

The ability to engineer geometrically well-defined antidots in large triangulene homologues allows for creating an entire family of triangulene quantum ring (TQR) structures with tunable high-spin ground state and magnetic ordering, crucial for next-generation molecular spintronic devices. Herein, we report the synthesis of an open-shell [7]triangulene quantum ring ([7]TQR) molecule on Au(111) through the surface-assisted cyclodehydrogenation of a rationally-designed kekulene derivative. Bond-resolved scanning tunneling microscopy (BR-STM) unambiguously imaged the molecular backbone of a single [7]TQR with a triangular zigzag edge topology, which can be viewed as [7]triangulene decorated with a coronene-like antidot in the molecular centre. Additionally, dI/dV mapping reveals that both inner and outer zigzag edges contribute to the edge-localized and spin-polarized electronic states of [7]TQR. Both experimental results and spin-polarized density functional theory calculations indicate that [7]TQR retains its open-shell septuple ground-state (� = 3) on Au(111). This work demonstrates a new route for the design of high-spin graphene quantum rings as the key components for future quantum devices.

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