Otro
Light-Induced Structural Change in Iridium Complexes Studied by Electron Spin Resonance
Registro en:
Journal Of Physical Chemistry A. Washington: Amer Chemical Soc, v. 118, n. 21, p. 3717-3725, 2014.
1089-5639
10.1021/jp503831p
WOS:000336772300002
0000-0003-0162-8273
Autor
Batagin-Neto, A.
Assis, A. P.
Lima, J. F.
Magon, C. J.
Yan, L.
Shao, M.
Hu, B.
Graeff, C. F. O.
Resumen
Iridium-based compounds are materials of great interest in the production of highly efficient organic light emitting diodes and several other applications. However, these organometallic compounds present relative low stability due to photodegradation processes still not well understood. In this work we investigated paramagnetic states induced by UV photoexcitation on iridium(III) bis[(4,6-fluorophenyl)-pyridinato-N,C2']picolinate (FIrpic) and iridium(III)-tris(2-phenyl-pyridine) (Ir(ppy)(3)) complexes dispersed in different polymeric matrices by electron spin resonance (ESR). Photogenerated charged states with relatively strong hyperfine interactions were observed and attributed to matrix/complex charge-transfer processes. Measurements of the signal amplitude decay after photoexcitation interruption were performed as a function of temperature. The photoinduced centers are thermally activated with energy barrier between 0.3 and 0.6 eV. Electronic structure calculations suggest that the signals observed by ESR are associated with metastable negatively charged Jr complexes distorted structures. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)