High-performance bipolar host materials for blue TADF devices with excellent external quantum efficiencies
| Autor: | Hyung Jong Kim, Young Hoon Son, Ju Sik Kang, Raju Lampande, Byoung Yeop Kang, Min Ju Cho, Chiho Lee, Joong Hwan Yang, Tae Ryang Hong, Jang Hyuk Kwon, Sungnam Park, Bang Sook Lee, Jin-Wuk Kim, Jong Kwan Bin, Donghoon Choi |
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| Rok vydání: | 2016 |
| Předmět: |
Materials science
Dopant Carbazole Nanotechnology 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Photochemistry 01 natural sciences Fluorescence 0104 chemical sciences Phthalonitrile chemistry.chemical_compound chemistry Dibenzothiophene Materials Chemistry OLED Thiophene Reactivity (chemistry) 0210 nano-technology |
| Zdroj: | Journal of Materials Chemistry C. 4:4512-4520 |
| ISSN: | 2050-7534 2050-7526 |
| DOI: | 10.1039/c6tc00385k |
| Popis: | New bipolar host molecules composed of carbazole, pyridoindole, and dibenzothiophene (DBT) were synthesized for blue thermally activated delayed fluorescence (TADF)-based organic light-emitting diodes (OLEDs). 2,8-Di(9H-carbazol-9-yl)dibenzo[b,d]thiophene, 9-(8-(9H-carbazol-9-yl)dibenzo[b,d]thiophen-2-yl)-9H-pyrido[2,3-b]indole, and 2,8-bis(9H-pyrido[2,3-b]indol-9-yl)dibenzo[b,d]thiophene were prepared based on the selective reactivity at the 2,8-positions of DBT. The new symmetric and asymmetric host materials exhibited high triplet energies (2.89–2.95 eV). 4,5-Di(9H-carbazol-9-yl)phthalonitrile (2CzPN) was selected as an emitting dopant for achieving sky-blue emissions in TADF-OLEDs. 2CzPN-doped TADF-OLEDs, whose configuration is ITO (50 nm)/HATCN (7 nm)/TAPC (75 nm)/host:6% 2CzPN (20 nm)/TmPyPB (50 nm)/LiF (15 nm)/Al (100 nm), showed low driving voltages and high external quantum efficiencies (EQEs). These results are attributed to the well-controlled bipolar character of the host giving a better charge balance in the emitting layer. In particular, the device containing ZDN:6% 2CzPN showed an unprecedentedly high EQE of 25.7% (at 0.074 mA cm−2). |
| Databáze: | OpenAIRE |
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