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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Light-Induced Structural Change in Iridium Complexes Studied by Electron Spin Resonance

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Author(s):
Batagin-Neto, A. [1] ; Assis, A. P. [2] ; Lima, J. F. [3] ; Magon, C. J. [3] ; Yan, L. [4] ; Shao, M. [4] ; Hu, B. [4] ; Graeff, C. F. O. [5]
Total Authors: 8
Affiliation:
[1] Univ Estadual Paulista, UNESP, BR-18409010 Sao Paulo - Brazil
[2] Univ Estadual Paulista, UNESP, POSMAT Programa Posgrad Ciencia & Tecnol Mat, BR-17033360 Sao Paulo - Brazil
[3] Univ Sao Paulo, Inst Fis Sao Carlos, BR-05508070 Sao Paulo - Brazil
[4] Univ Tennessee, Knoxville, TN 37996 - USA
[5] Univ Estadual Paulista, UNESP, DF FC, BR-17033360 Sao Paulo - Brazil
Total Affiliations: 5
Document type: Journal article
Source: Journal of Physical Chemistry A; v. 118, n. 21, p. 3717-3725, MAY 29 2014.
Web of Science Citations: 4
Abstract

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. (AU)

FAPESP's process: 12/03116-7 - Simulation of electronic and optical properties of organic materials
Grantee:Augusto Batagin Neto
Support Opportunities: Scholarships in Brazil - Doctorate