Time-resolved study of luminescence in highly luminescent disubstituted polyacetylene and its blend with poorly luminescent monosubstituted polyacetylene

Hidayat, Rahmat; Tatsuhara, Satoshi; Kim, Dong Wook; Ozaki, Masanori; Yoshino, Katsumi; Teraguchi, Masahiro; Masuda, Toshio

doi:10.1103/physrevb.61.10167

Cited by 50 publications

(38 citation statements)

References 34 publications

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“…The recent observation of strong PL in phenyl-disubstituted polyacetylenes (PDPAs) (see Fig. 1) [8][9][10][11][12][13] is difficult to explain within the above simple theoretical picture. These systems consist of a backbone polyene chain, the hydrogen atoms of which have been replaced with phenyl groups 14 , a process that we term as "site substitution", in order to distinguish it from bond substitution.…”

Section: Introductionmentioning

confidence: 99%

“…Before proceeding further, we therefore present a brief overview of the experimental situation 8,9,12,13 . Three different classes of phenyl acetylenes have been synthesized, which include, (i) poly-phenylacetylenes (PPAs), which are obtained by substituting alternate hydrogen atoms of t-PA with phenyl groups 14 , (ii) polyphenylalkylpolyacetylenes (PAPAs), in which alternate hydrogens of t-PA are replaced with alkyl and phenyl groups 14 , respectively, and (iii) the PDPAs, already mentioned above.…”

Section: Introductionmentioning

confidence: 99%

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Electron-correlation-induced transverse delocalization and longitudinal confinement in excited states of phenyl-substituted polyacetylenes

2000

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Electron-electron interactions in general lead to both ground state and excited state confinement. We show, however, that in phenyl-substituted polyacetylenes electron-electron interactions cause enhanced delocalization of quasiparticles in the optically excited state from the backbone polyene chain into the phenyl groups, which in turn leads to enhanced confinement in the chain direction. This co-operative delocalization-confinement lowers the energy of the one-photon state and raises the relative energy of the lowest two-photon state. The two-photon state is slightly below the optical state in mono-phenyl substituted polyacetylenes, but above the optical state in di-phenyl substituted polyacetylenes, thereby explaining the strong photoluminescence of the latter class of materials. We present a detailed mechanism of the crossover in the energies of the one-and two-photon states in these systems. In addition, we calculate the optical absorption spectra over a wide wavelength region, and make specific predictions for the polarizations of low and high energy transitions that can be tested on oriented samples. Within existing theories of light emission from π-conjugated polymers, strong photoluminescence should be restricted to materials whose optical gaps are larger than that of trans-polyacetylene. The present work show that conceptually at least, it is possible to have light emission from systems with smaller optical gaps. 42.70.Jk,71.20.Rv,78.30.Jw

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electron-correlation-induced transverse delocalization and longitudinal confinement in excited states of phenyl-substituted polyacetylenes

2000

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“…[10][11][12][13][14][15][16][17] The interesting aspect of the linear optical properties of these materials is that they exhibit strong photoluminescence ͑PL͒, despite their structural similarities to trans-polyacetylene, which is well known to be nonphotoluminescent. 14 In a series of theoretical studies, we explained the strong PL exhibited by PDPA's in terms of reduced electron-correlation effects caused by the delocalization of excitons in the transverse direction because of the presence of phenyl rings in that direction.…”

Section: Introductionmentioning

confidence: 99%

Theory of nonlinear optical properties of phenyl-substituted polyacetylenes

Shukla

2004

Phys. Rev. B

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In this paper we present a theoretical study of the third-order nonlinear optical properties of poly͑diphe-nyl͒polyacetylene ͑PDPA͒ pertaining to the third-harmonic-generation process. We study the aforesaid process in PDPA's using both the independent electron Hückel model, as well as correlated-electron Pariser-Parr-Pople ͑P-P-P͒ model. The P-P-P model based calculations were performed using various configuration-interaction ͑CI͒ methods such as the the multireference-singles-doubles CI and the quadruples-CI methods, and both the longitudinal and the transverse components of third-order susceptibilities were computed. The Hückel-model calculations were performed on oligo-PDPA's containing up to 50 repeat units, while correlated calculations were performed for oligomers containing up to ten unit cells. At all levels of theory, the material exhibits highly anisotropic nonlinear optical response, in keeping with its structural anisotropy. We argue that the aforesaid anisotropy can be divided over two natural energy scales: ͑a͒ the low-energy response is predominantly longitudinal and is qualitatively similar to that of polyenes, while ͑b͒ the high-energy response is mainly transverse, and is qualitatively similar to that of trans-stilbene.

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“…[1][2][3][4][5][6][7][8] Despite their structural similarities to trans-polyacetylene-which is well known to be nonphotoluminescent-PDPA's are known to exhibit photoluminescence ͑PL͒ with a large quantum efficiency. 5 We explained this apparently contradictory behavior in our earlier papers [9][10][11] in terms of the reduced electron correlation effects caused by the delocalization of the exciton in the transverse direction because of the presence of phenyl rings.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced absorption in disubstituted polyacetylenes: Comparison of theory with experiments

Sony

Shukla

2005

Phys. Rev. B

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In a recently performed experiment, ͓Korovyanko et al.Phys. Rev. B 67, 035114 ͑2003͔͒ have measured the photoinduced absorption ͑PA͒ spectrum of phenyl-disubstituted polyacetylenes ͑PDPA's͒ from the 1B u and 2A g excited states. In the 1B u PA spectrum they identified two main features, namely, PA1 and PA2, while in the 2A g spectrum they identified only one feature called PA g . In this paper we present a theoretical study of the 1B u and 2A g PA spectra of oligo-PDPA's using the correlated-electron Pariser-Parr-Pople model and various configuration interaction methodologies. We compare the calculated spectra with the experiments, as well as with the calculated spectra of polyenes of the same conjugation lengths. The calculated spectra are in good agreement with the experiments. Based upon our calculations, we identify PA1 as the mA g state and PA g as the nB u state of the polymer. Regarding the PA2 feature, we present our speculations. Additionally, it is argued that the nature of the excited states contributing to the 2A g -PA spectra of oligo-PDPA's is qualitatively different from those contributing to the spectra of polyenes.

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Time-resolved study of luminescence in highly luminescent disubstituted polyacetylene and its blend with poorly luminescent monosubstituted polyacetylene

Cited by 50 publications

References 34 publications

Electron-correlation-induced transverse delocalization and longitudinal confinement in excited states of phenyl-substituted polyacetylenes

Electron-correlation-induced transverse delocalization and longitudinal confinement in excited states of phenyl-substituted polyacetylenes

Theory of nonlinear optical properties of phenyl-substituted polyacetylenes

Photoinduced absorption in disubstituted polyacetylenes: Comparison of theory with experiments

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