Optical properties of the semiconducting “metal-like” complex (NMe3H) (I) (TCNQ)

Tanner, D. B.; Deis, J. E.; Epstein, Arthur J.; Miller, Joel S.

doi:10.1016/0038-1098(79)90321-1

Cited by 41 publications

(4 citation statements)

References 15 publications

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“…4 we present the reflectance spectra of DTA-(TCNQ)z for polarization parallel to the a stacking axis as a function of temperature. The broad features at 295 K are identical to those found in many other TCNQ organic conductors (13)(14)(15)(16). We observe five distinct large TCNQ vibration bands around 700, 1200, 1300, 1600, and 2200 cm-I, which are usually associated with IR active Ag modes of the TCNQ anion (4,14).…”

Section: X-ray Crystallography2supporting

confidence: 81%

A study of the phase transition in semiconducting 1:2 tetracyanoquinodimethane charge transfer complexes with dipropylamine derivatives: X-ray structure and polarized reflection spectra

Truong¹,

Pépin²,

Bandrauk³

et al. 1991

Can. J. Chem.

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Chem. 69, 1804 (1991).The donors dipropylamine (DPA), methyldipropylamine (MDPA), and ethyldipropylamine (EDPA) from 1:2 charge transfer complexes with the acceptor tetracyanoquinodimethane (TCNQ). All crystals in the above series are semiconductors and undergo a first-order phase transition at the temperature around 210 K as obtained from conductivity measurements. The X-ray structure of DPA-(TCNQ)? was obtained as a function of temperature, and shows a distinct order-disorder transition in the hydrogen-bond network between donors and acceptors. Polarized reflection spectra on single crystals of these compounds were measured as a function of temperature in the frequency range from 400 to 4000 crn-'. A detailed study of the e N modes of TCNQ indicates this mode is strongly influenced by the transition due to it being hydrogen bonded to the donors. The reflection coefficients of the IR active Ag modes of TCNQ also undergo a sharp discontinuity at the transition temperature. These results are interpreted as due to a cooperative order-disorder and electronic spin -Peierls transition.Key words: organic semiconductors, X-ray structure, polarized reflection spectra, phase transition, cooperative orderdisorder transition, spin-Peierls transition. La dipropylamine (DPA), la mCthyldipropylamine (MDPA) et l'ithyldipropylamine (EDPA) agissent comme donneurs pour former des complexes de transfert de charge 1 : 2 avec le titracyanoquinornithane (TCNQ) qui agit comme accepteur. Tous les cristaux des series sus-mentionnies sont des semi-conducteurs et, d'aprks les mesures de conductiviti, ils subissent une transition de phase du premier ordre B une tempirature d'environ 210 K. Faisant appel B la diffraction des rayons-X, on a dCterminC la structure du complexe DPA-(TCNQ)? en fonction de la tempirature; on observe une transition distincte ordreldCsordre dans le riseau des liaisons hydrogknes entre donneurs et accepteurs. On a mesuri le spectre de riflexion polarisie de cristaux uniques en fonction de la tempirature entre 400 et 4000 cm-' . Une Ctude dttaillCe des modes C=N du TCNQ indique que ce mode est fortement influencC par la transition; cet effet est dfi au fait que cette liaison est impliquie dans une liaison hydrogkne avec les donneurs. Les coefficients de riflexion des modes Ag du TCNQ actifs en infrarouge subissent aussi une discontinuiti importante au niveau de la temperature de transition. On interprkte ces risultats en fonction d'une transition coopirative ordreldksordre et spin ClectroniquelPeierls.

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Section: X-ray Crystallography2supporting

confidence: 81%

A study of the phase transition in semiconducting 1:2 tetracyanoquinodimethane charge transfer complexes with dipropylamine derivatives: X-ray structure and polarized reflection spectra

Truong¹,

Pépin²,

Bandrauk³

et al. 1991

Can. J. Chem.

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“…3-6. and is still visible at room temperature. This behaviour resembles that observed for the higherfrequency a, modes in the mid-infrared ( 1 I , 12,26,27). Figure 4 shows the unexpected temperature dependence of the 126 cm-' mode which starts to grow strongly only below 100 K. This corresponds to the growth of the second distortion which precedes the phase transition at 89 K. The mode could, therefore, be a torsion of the methyl groups if their rotation is indeed frozen out at this temperature, or it may be one for which the intensity depends strongly on the angle of tilt of the TCNQ molecules.…”

Section: Resultssupporting

confidence: 75%

“…Indeed, the dc conductivity is analyzed on the basis of a gap of -0.14 eV (-1 I00 cm-') which does not change through TI. This is supported by the optical data of Tanner et al (12,13), who find a conductivity which starts from the dc value of 20 (R cm)-' and rises to a broad peak of -170 (R cm)-I at approximately 2000 cm-I. This is little changed at 80 K and so the authors conclude that at 150 K there is only a small change in the gap, but a large change in the mobility.…”

Section: Introductionsupporting

confidence: 53%

“…In all of these materials the totally symmetric a, modes, which are usually the strongest activated modes, are infrared irz~lctive in the undistorted material. In the low-resolution midinfrared reflectivity studies of (TMA)(I)(TCNQ) by Tanner et al (12,13), the strong features have been identified with the a, modes, both at room temperature Can. J. Phys.…”

Section: Introductionmentioning

confidence: 96%

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Far-infrared powder spectrum of (N(CH₃)₃D)(I)(TCNQ)

Eldridge¹,

Fortier²,

Bates³

et al. 1983

Can. J. Phys.

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We present the powder absorption spectrum of (TMA)(I)(TCNQ) in the far-infrared as a function of temperature. Below 160 K new absorption features appear and others increase in intensity. This behaviour supports the electron-and neutrondiffraction evidence of a distortion on the TCNQ chains below the first phase-transition temperature. Effects due to the second phase transition at 89 K are also observed. The results of a group-theoretical analysis are presented. These show that totally-symmetric internal modes n, are to be expected in the infrared spectra of this compound even in the undistorted phase.Nous prksentons le spectre d'absorption de poudre de (TMA) (I) (TCNQ) dans I'infrarouge lointain, en fonction de la tempkrature. Au dessous de 160 K , de nouvelles frkquences d'absorption apparaissent et d'autres augmentent d'intensitt. Ce comportement confirme les indications de la diffraction des neutrons et des klectroni sur I'existence d'une distorsion des chaines TCNQ au-dessous de la premikre temptrature dc transition de phase. On observe aussi des effets dus a la seconde transition de phase a 89 K. Les rtsultats d'une analyse par thkorie des groupes sont prtsentks. Ils montrent que des modes internes totalement symktriques (a,) doivent itre attendus dans le spectre infrarouge de ce compost, mime dans la phase sans distorsion.[Traduit par le journal]Can.

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Steuerung der elektronischen Struktur organischer Leiter am Beispiel von [NMP][TCNQ]-Charge-Transfer-Komplexen

Miller

Epstein

1987

Angew. Chem.

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Optical properties of the semiconducting “metal-like” complex (NMe3H) (I) (TCNQ)

Cited by 41 publications

References 15 publications

A study of the phase transition in semiconducting 1:2 tetracyanoquinodimethane charge transfer complexes with dipropylamine derivatives: X-ray structure and polarized reflection spectra

A study of the phase transition in semiconducting 1:2 tetracyanoquinodimethane charge transfer complexes with dipropylamine derivatives: X-ray structure and polarized reflection spectra

Far-infrared powder spectrum of (N(CH₃)₃D)(I)(TCNQ)

Steuerung der elektronischen Struktur organischer Leiter am Beispiel von [NMP][TCNQ]-Charge-Transfer-Komplexen

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Optical properties of the semiconducting “metal-like” complex (NMe3H) (I) (TCNQ)

Cited by 41 publications

References 15 publications

A study of the phase transition in semiconducting 1:2 tetracyanoquinodimethane charge transfer complexes with dipropylamine derivatives: X-ray structure and polarized reflection spectra

A study of the phase transition in semiconducting 1:2 tetracyanoquinodimethane charge transfer complexes with dipropylamine derivatives: X-ray structure and polarized reflection spectra

Far-infrared powder spectrum of (N(CH3)3D)(I)(TCNQ)

Steuerung der elektronischen Struktur organischer Leiter am Beispiel von [NMP][TCNQ]-Charge-Transfer-Komplexen

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Far-infrared powder spectrum of (N(CH₃)₃D)(I)(TCNQ)