Different RISC rates in benzoylpyridine-based TADF compounds and their implications for solution-processed OLEDs
| Autor: | Egidijus Kamarauskas, Karolis Kazlauskas, Virginijus Ruibys, Gediminas Kreiza, Saulius Juršėnas, Olegas Bobrovas, Povilas Adomėnas, Domantas Berenis |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Carbazole Process Chemistry and Technology General Chemical Engineering 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Photochemistry 01 natural sciences Photon upconversion 0104 chemical sciences Solution processed chemistry.chemical_compound Intersystem crossing chemistry OLED 0210 nano-technology |
| Zdroj: | Dyes and Pigments. 182:108579 |
| ISSN: | 0143-7208 |
| DOI: | 10.1016/j.dyepig.2020.108579 |
| Popis: | Reverse intersystem crossing (RISC) rate is among the key parameters of TADF compounds affecting triplet upconversion and annihilation processes, and thus determining efficiency roll-off in TADF-OLEDs. Herein, control of RISC rate (kRISC) in a series of benzoylpyridine-based TADF compounds via carbazole donor linking positions is demonstrated. Regardless of the similar singlet-triplet energy splitting found in the compounds with meta- or para-carbazole linking topologies, meta-Cz compounds exhibited stronger singlet-triplet state coupling resulting in 10-fold larger kRISC (up to ~2 × 106 s−1) as that in para-Cz counterparts. Different kRISC was shown to have important implications for the solution-processed TADF-OLEDs based on the benzoylpyridines. Explicitly, in the non-doped devices based on neat meta-Cz emissive layers, larger kRISC was crucial for the reduced roll-off. Conversely, in 1.2 wt% rubrene-doped hyperfluorescent devices employing benzoylpyridines as TADF hosts, insignificant roll-off was observed irrespective of kRISC, provided it is above 105 s−1. The obtained results give insight into the possibilities of controlling kRISC in benzoylpyridines and demonstrate its importance for efficiency roll-off of TADF and hyperfluorescent OLEDs. |
| Databáze: | OpenAIRE |
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