Exciplex Organic Light-Emitting Diodes with Nearly 20% External Quantum Efficiency: Effect of Intermolecular Steric Hindrance between the Donor and Acceptor Pair
| Autor: | Ssu Yu Liao, Pei Yun Huang, Chih-Chun Lin, Mu Jeng Cheng, Man Ping Huang, Chien-Hong Cheng, Zih Siang Hong, Tien-Lin Wu |
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| Rok vydání: | 2019 |
| Předmět: |
Photoluminescence
Materials science Carbazole Intermolecular force Quantum yield 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Excimer Photochemistry 01 natural sciences Acceptor 0104 chemical sciences chemistry.chemical_compound chemistry OLED General Materials Science Quantum efficiency 0210 nano-technology |
| Zdroj: | ACS Applied Materials & Interfaces. 11:19294-19300 |
| ISSN: | 1944-8252 1944-8244 |
| DOI: | 10.1021/acsami.9b04365 |
| Popis: | Exciplex emitters have emerged as an important class of thermally activated delayed fluorescence (TADF) materials for highly efficient OLEDs. A TADF exciplex emitter requires an intermolecular donor/acceptor pair. We have synthesized a bipolar donor-type material, DPSTPA, which was used to pair with known acceptor materials (2CzPN, 4CzIPN, or CzDBA). The OLEDs based on the exciplex emitters, DPSTPA/X, where X = 2CzPN and CzDBA, give green and orange-red colors with record-high external quantum efficiencies (EQEs) of 19.0 ± 0.6 and 14.6 ± 0.4%, respectively. In contrast, the exciplex pair DPSTPA/4CzIPN gave a very low photoluminescence quantum yield (PLQY) and a very low EQE value of the device. The DFT calculations indicate that the intermolecular distance between the donor and the acceptor plays a key factor for the PLQY and EQE. The observed low PLQY and the poor device performance for the DPSTPA/4CzIPN pair are probably because of the relatively long distance between the DPSTPA and 4CzIPN in the thin film caused by the four congested carbazole (Cz) groups of 4CzIPN, which effectively block the interaction of the nitrile acceptor with the triphenylamino donor of DPSTPA. |
| Databáze: | OpenAIRE |
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