Intermolecular energy transfer involving an iridium complex studied by a combinatorial method
| Autor: | Teruyuki Mitsumori, Edin H. Suljovrujić, Vojislav I. Srdanov, A. Ignjatovic, Fred Wudl |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | The Journal of Chemical Physics. 121:3745-3750 |
| ISSN: | 1089-7690 0021-9606 |
| DOI: | 10.1063/1.1765094 |
| Popis: | 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-C(1), 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 0.0003chi(Ir(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 Forster mechanism with the Forster radius of 30 A. The CBPxIr(pin)(3) composite has the highest photoluminescence quantum efficiency approximately 0.95, for chi(Ir(pin)(3) )=0.03 and is characterized by a structured green emission (lambda(max)=538 nm) originating from the ligand-centered (pi-pi(*))(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 (lambda(max)=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 (pi-pi(*))(3) state is quenched in Ir(pin)(3) molecules that are in a direct contact with each other. |
| Databáze: | OpenAIRE |
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