Novel iridium(III) complexes based on 2-(2,2’-bithien-5-yl)-quinoline. Synthesis, photophysical, photochemical and DFT studies

Autor: Maciej Sojka, Michal Filapek, Grażyna Szafraniec-Gorol, Lidia Żur, Maria Jaworska, Witold Danikiewicz, Bartosz Boharewicz, Iwona Grudzka-Flak, Agnieszka Iwan, Marta Sołtys, Joanna Pisarska, Aneta Slodek, Sylwia Czajkowska, Stanisław Krompiec
Rok vydání: 2015
Předmět:
Zdroj: Materials Chemistry and Physics. 162:498-508
ISSN: 0254-0584
Popis: Four novel cyclometalated iridium(III) complexes: [Ir(q-bt-Ph) 2 (phen)]PF 6 , [Ir(q-bt-Ph) 2 (acac)], [Ir(q-bt-Me) 2 (bpy)]PF 6 and [Ir(q-bt-Me) 2 (acac)] (where q-bt-Ph, q-bt-Me correspond to 2-(2,2’-bithien-5-yl)-4-phenylquinoline and 2-(2,2’-bithien-5-yl)-4-methylquinoline), are reported. The complexes were characterized by NMR, FTIR and HRMS. The optical, electrochemical properties and thermal stability of novel iridium(III) complexes were thoroughly investigated. The complexes emit a light in the narrow range of 693–707 nm. The optical study showed that replacement of fragment in the main quinoline ligand did not affect wavelength of the emitted light. On the other hand, the modification of the ancillary ligand and substituent in the quinoline ring caused the increase of the photoluminescence quantum yields. Electrochemical experiments demonstrate that the oxidation process for complexes [Ir(q-bt-Ph) 2 (phen)]PF 6 and [Ir(q-bt-Ph) 2 (acac)] was reversible (or quasi-reversible) and well detectable whereas for complexes with quinoline substituted by methyl group was irreversible, even at low temperature (−70 °C). The electrochemical and photophysical studies have been well confirmed by density functional theory (DFT) calculations. In addition, bulk heterojunction polymer solar cells based on complexes [Ir(q-bt-Ph) 2 (phen)]PF 6 and [Ir(q-bt-Ph) 2 (acac)] were fabricated. Only the solar cell incorporating [Ir(q-bt-Ph) 2 (acac)] exhibited a photovoltaic effect. The architecture of the cell was ITO/PEDOT:PSS/P3HT:PCBM:[Ir(q-bt-Ph) 2 (acac)]/Al. A power conversion efficiency of 0.25% was measured under 1 sun illumination using an AM 1.5G filter to simulate the solar spectrum.
Databáze: OpenAIRE