| Autor: |
Suljovrujic, E., Ignjatovic, A., Srdanov, V. I., Mitsumori, T., Wudl, F. |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 8/22/2004, Vol. 121 Issue 8, p3745-3750, 6p, 6 Graphs |
| Abstrakt: |
A recently developed combinatorial method utilizing angular dependence of evaporation rate was used to create compositional spread thin film libraries of Tris(2-pyridin-2-yl-indolizino[3,4,5-ab] isoindole-C1, N′)iridium(III) [Ir(pin)3] and 4,4′-N,N′-dicarbazol-biphenyl (CBP) composite, with the molar fraction of Ir(pin)3 complex varying in the 0.0003<χIr(pin)3<0.96 range. Spatially correlated absorbance and photoluminescence (PL) measurements were used to quantify luminescence quenching of photo-excited CBP molecules by the Ir(pin)3 complex as a function of the average distance between two molecules. It was found that the CBP→Ir(pin)3 energy transfer proceeds by the Förster mechanism with the Förster radius of 30 Å. The CBP×Ir(pin)3 composite has the highest photoluminescence quantum efficiency ≈0.95, for χIr(pin)3=0.03 and is characterized by a structured green emission (λmax=538 nm) originating from the ligand-centered (π-π*)3 state of the Ir(pin)3 complex. On the contrary, the PL spectra of Ir(pin)3 bulk are characterized by a weak red emission (λmax=673 nm) attributed to the lowest metal-to-ligand charge transfer state. A statistical analysis based on a binomial distribution indicates that the emission from the (π-π*)3 state is quenched in Ir(pin)3 molecules that are in a direct contact with each other. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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