Optical and Electroluminescence Studies of Original Iridium Metal Complexes with Aromatic Staking Effect
Proceedings Vol.PC12149: Organic Electronics and Photonics: Fundamentals and Devices III 2022
Margarita Anna Zommere, Kirills Dmitrijevs, Žanis Sisojevs, Kaspars Traskovskis, Valdis Kokars, Aivars Vembris

Organic light-emitting diodes (OLEDs) are becoming more widely used in displays due to their pure colour and high efficiency. Second generation emitters are heavy metal-based emitters, which can accelerate the radiative deactivation through phosphorescence from the first triplet state to the ground state and facilitate intersystem crossing from the first singlet state to the first triplet. This process allows phosphorescent emitters to reach 100% of the conversion of excited states into the light and increase OLEDs' external quantum efficiencies. Despite, the high efficiency, OLEDs have a relatively short lifespan. To increase longevity an intramolecular stacking process between the flexibly bridged ancillary aromatic group and the surface of non-ionic iridium (III) complex core was proposed as an approach to obtain phosphorescent OLED second-generation emitters with a reduced aggregation tendency. In the work, the original Iridium metal complexes were developed and their light-emitting properties were investigated. Bis[2-(4-(hydroxymethyl)phenyl)pyridinato-C2,N](picolinato)iridium was used as a base compound where hydroxygroup was functionalized with methyl (AZ-B10), benzyl succinate (AR415) and ((perfluorophenyl)methyl) succinate (KD29) groups. For all the compounds the emission spectra, photoluminescence kinetics and photoluminescence quantum yield were measured in both solutions and thin films. The solutions were made from degassed tetrahydrofuran and host-guest thin films were prepared with 5 and 10 wt% of emitters in PVK matrix. All compounds emit light in the green spectral region. AR415 and KD29 compounds have more than 90% PLQY in solution and more than 25 % in thin films which are promising values for OLED systems. Finally, OLED with the structure ITO/PEDOT:PSS/TCTA:Emitter/TPBi/LiF/Al were prepared. Emitter concentration in TCTA was varied from 5 to 20 wt%. The emitter layer was prepared by two methods: spin-coating and thermal evaporation in a vacuum. The OLED performance in relation to the optical properties of the original Iridium metal complex will be discussed.


Keywords
phosphorescence, iridium complex
DOI
10.1117/12.2621809
Hyperlink
https://www.spiedigitallibrary.org/conference-proceedings-of-spie/PC12149/PC121491E/Optical-and-electroluminescence-studies-of-original-iridium-metal-complexes-with/10.1117/12.2621809.full

Zommere, M., Dmitrijevs, K., Sisojevs, Ž., Traskovskis, K., Kokars, V., Vembris, A. Optical and Electroluminescence Studies of Original Iridium Metal Complexes with Aromatic Staking Effect. In: Proceedings Vol.PC12149: Organic Electronics and Photonics: Fundamentals and Devices III, France, Strasbourg, 3-7 April, 2022. Strasbourg: 2022, pp.PC121491E-PC121491E. Available from: doi:10.1117/12.2621809

Publication language
English (en)
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