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Sökning: onr:"swepub:oai:DiVA.org:kth-14712" > Structures, electro...

LIBRIS Formathandbok  (Information om MARC21)
FältnamnIndikatorerMetadata
00004961naa a2200553 4500
001oai:DiVA.org:kth-14712
003SwePub
008100805s2005 | |||||||||||000 ||eng|
0247 a https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147122 URI
0247 a https://doi.org/10.1021/ja044628b2 DOI
040 a (SwePub)kth
041 a engb eng
042 9 SwePub
072 7a ref2 swepub-contenttype
072 7a for2 swepub-publicationtype
1001 a Yu, G.4 aut
2451 0a Structures, electronic states, photoluminescence, and carrier transport properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles
264 c 2005-04-12
264 1b American Chemical Society (ACS),c 2005
338 a print2 rdacarrier
500 a QC 20100525
520 a The excellent electroluminescent (EL) properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles, 1-methyl-1,2,3,4,5-pentaphenylsilole (MPPS), and 1,1,2,3,4,5-hexaphenylsilole (HPS) have been found. Despite some studies devoted to these materials, very little is known about the real origin of their unique EL properties. Therefore, we investigated the structures, photoluminescence (PL), and charge carrier transport properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles as well as the effect of substituents on these characteristics. The single crystals of the three siloles involving 1,1-dimethyl-2,3,4,5-tetraphenylsilole (DMTPS), MPPS, and HIPS were grown and their crystal structures were determined by X-ray diffraction. Three siloles have nonplanar molecular structures. The substituents at 1,1-positions enhance the steric hindrance and have predominant influence on the twisted degree of phenyl groups at ring carbons. This nonplanar structure reduces the intermolecular interaction and the likelihood of excimer formation, and increases PL efficiency in the solid state. The silole films show high fluorescence quantum yields (75-85%), whereas their dilute solutions exhibit a faint emission. The electronic structures of the three siloles were investigated using quantum chemical calculations. The highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) are mainly localized on the silole ring and two phenyl groups at 2,5-positions in all cases, while the LUMOs have a significant orbital density at two exocyclic Si-C bonds. The extremely theoretical studies of luminescent properties were carried out. We calculated the nonradiative decay rate of the first excited state as well as the radiative one. It is found that the faint emission of DMTPS in solutions mainly results from the huge nonradiative decay rate. In solid states, molecular packing can remarkably restrict the intramolecular rotation of the peripheral side phenyl ring, which has a large contribution to the nonradiative transition process. This explains why the 1,1-disubstituted 2,3,4,5-tetraphenylsiloles in the thin films exhibit high fluorescence quantum yields. The charge carrier mobilities of the MPPS and HPS films were measured using a transient EL technique. We obtained a mobility of 2.1 x 10(-6) cm(2)/V(.)s in the MPPS film at an electric field of 1.2 x 10(6) V/cm. This mobility is comparable to that of Alq(3), which is one of the most extensively used electron transport materials in organic light-emitting diodes (LEDs), at the same electric field. The electron mobility of the HPS film is about similar to 1.5 times higher than that of the MPPS film. To the best of our knowledge, this kind of material is one of the most excellent emissive materials that possess both high charge carrier mobility and high PL efficiency in the solid states simultaneously. The excellent EL performances of MPPS and HPS are presumably ascribed to these characteristics.
653 a light-emitting-diodes
653 a organic electroluminescent devices
653 a restricted intramolecular rotation
653 a conjugated polymers
653 a tris(2,2'-bipyridine)ruthenium(ii) complexes
653 a phosphorescent sensitizer
653 a photophysical properties
653 a polyatomic-molecules
653 a silole derivatives
653 a absorption-spectra
7001 a Yin, S. W.4 aut
7001 a Liu, Y. Q.4 aut
7001 a Chen, J. S.4 aut
7001 a Xu, X. J.4 aut
7001 a Sun, X. B.4 aut
7001 a Ma, D. G.4 aut
7001 a Zhan, X. W.4 aut
7001 a Peng, Q.4 aut
7001 a Shuai, Z. G.4 aut
7001 a Tang, B. Z.4 aut
7001 a Zhu, D. B.4 aut
7001 a Fang, W. H.4 aut
7001 a Luo, Yiu KTH,Teoretisk kemi4 aut0 (Swepub:kth)u126eitw
7102 a KTHb Teoretisk kemi4 org
7730 t Journal of the American Chemical Societyd : American Chemical Society (ACS)g 127:17, s. 6335-6346q 127:17<6335-6346x 0002-7863x 1520-5126
8564 8u https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-14712
8564 8u https://doi.org/10.1021/ja044628b

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